Prevalence and incidence of cancer amongst adults with intellectual disability — a systematic review and meta-analysis protocol

Martin McMahon; Andrew Wormald; Jessica Eustace-Cook; Mary McCarron; Philip McCallion; Valerie Smith

doi:10.12688/hrbopenres.13740.1

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Study Protocol

Prevalence and incidence of cancer amongst adults with intellectual disability — a systematic review and meta-analysis protocol

[version 1; peer review: 1 approved, 1 approved with reservations]

Martin McMahon ^1,2, Andrew Wormald², Jessica Eustace-Cook¹, Mary McCarron^1,2, Philip McCallion^2,3, Valerie Smith¹

Martin McMahon ^1,2, Andrew Wormald², [...] Jessica Eustace-Cook¹, Mary McCarron^1,2, Philip McCallion^2,3, Valerie Smith¹

PUBLISHED 13 Sep 2023

Author details Author details

¹ School of Nursing & Midwifery, The University of Dublin Trinity College, Dublin, D02 PN40, Ireland
² Trinity Centre for Ageing with Intellectual Disability (TCAID), The University of Dublin Trinity College, School of Nursing & Midwifery, Dublin, Ireland
³ School of Social Work (College of Public Health), Temple University, Philadelphia, Pennsylvania, USA

Martin McMahon
Roles: Conceptualization, Data Curation, Investigation, Methodology, Project Administration, Writing – Original Draft Preparation, Writing – Review & Editing

Andrew Wormald
Roles: Methodology, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Jessica Eustace-Cook
Roles: Data Curation, Methodology, Software, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Mary McCarron
Roles: Conceptualization, Methodology, Resources, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Philip McCallion
Roles: Conceptualization, Methodology, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Valerie Smith
Roles: Methodology, Software, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS

This article is included in the Dementia Trials Ireland (DTI) and Dementia Research Network Ireland (DRNI) gateway.

Abstract

Background: People with intellectual disabilities have poorer health and die earlier than their peers without identified disabilities. This difference represents a significant inequality. Until recently, it was considered that cancer was less common in this population, mainly because they did not live long enough to develop age-related cancers. However, recent evidence has identified that people with intellectual disabilities may be at an increased risk of developing cancer but more likely to present for medical treatment at a later stage when cancer has spread. Nonetheless, the evidence is lacking and there is a need to understand the prevalence and incidence of cancer and subtypes of cancer in adults with intellectual disabilities.

Methods A systematic review and meta-analysis will be undertaken to investigate the prevalence and incidence of cancer and subtypes of cancer in adults with an intellectual disability. The JBI Systematic reviews of prevalence and incidence and the PRISMA-P (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed to develop this protocol. Electronic databases will be searched using predefined search terms to identify relevant studies using the Condition Context Population (CoCoPop) framework. Eligible studies should be observational and have published baseline data that have estimated or presented data on the prevalence or incidence of cancer in adults with intellectual disability. To assess the methodological quality of studies included in this review a modified version of the JBI Critical Appraisal Checklist for Studies Reporting Prevalence Data will be used. Prevalence and incidence proportions will be analysed separately with individual study data being pooled using the DerSimonian-Laird proportion method and a random effects meta-analysis will be undertaken.

Discussion: This review will advance the epidemiological evidence to identify where targeted cancer care interventions are needed to help reduce the inequalities that this population experiences.

Systematic review registration: PROSPERO registration number: CRD42023423584

Keywords

Intellectual disability, cancer, neoplasms, systematic review

Corresponding author: Martin McMahon

Competing interests: No competing interests were disclosed.

Grant information: This research was funded by the Health Research Board ‘IDS-TILDA-2021-001’.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright: © 2023 McMahon M et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: McMahon M, Wormald A, Eustace-Cook J et al. Prevalence and incidence of cancer amongst adults with intellectual disability — a systematic review and meta-analysis protocol [version 1; peer review: 1 approved, 1 approved with reservations]. HRB Open Res 2023, 6:51 (https://doi.org/10.12688/hrbopenres.13740.1) First published: 13 Sep 2023, 6:51 (https://doi.org/10.12688/hrbopenres.13740.1) Latest published: 02 Feb 2024, 6:51 (https://doi.org/10.12688/hrbopenres.13740.2)

Introduction

Intellectual disability is a condition originating during the developmental period characterised by significantly below average intellectual functioning and adaptive behaviour¹. Internationally, the prevalence rate of intellectual disability is approximately 1–3%². People with intellectual disability are a vulnerable group with a complex health profile³ that experience high levels of morbidity⁴, mortality^5,6 and general health inequalities⁷ with regard to healthcare access and utilisation^8,9, health surveillance¹⁰, discriminatory attitudes¹¹ and diagnostic overshadowing¹². The consequence of such inequalities is well documented. For example, The Confidential Inquiry into Premature Deaths of People with Intellectual Disabilities in England revealed contributory causes to avoidable and untimely deaths in this demographic population¹³. The inquiry found there is a substantial risk of premature mortality for people with intellectual disabilities. This risk may be attributed to untreated illnesses and deficiencies in the healthcare system for this population¹⁴.

Inherent in the need to understand and address these inequalities that exist in this population is the critical need to document and detail the diseases this population present with and die from. Historically, this has been challenging owing to diagnostic (for example often-atypical disease-related presentations) and methodological constraints (for example identifying people with intellectual disability) and for this reason limited disease related epidemiological evidence exists in this population. One noticeable disparity in the absence of literature concerns cancer. In Ireland, cancer is now the leading cause of death replacing heart disease¹⁵; however, in the Irish intellectual disability population respiratory diseases are reported to be the leading cause of death¹⁶. One plausible argument is that as cancer is a disease of old age¹⁷ people with intellectual disability do not live long enough to be diagnosed with age related cancers notwithstanding the increases in their longevity over the last number of decades¹⁸.

Nevertheless, there is some population level evidence emerging from Europe that identifies that people with intellectual disability are at an increased risk of developing any cancer, as well as several specific cancer types (e.g. cancers of the gastrointestinal system)¹⁹ and are more likely to die from cancers than the general population²⁰. In contrast, a recent systematic review³ examining the prevalence of physical health conditions in people with intellectual disability observed that solid cancers are likely to occur at the same or lower rates than the general population citing under detection as being a likely factor. Under detection of cancer in people with an intellectual disability is a particular concern. A recent English study linking data from the LeDeR mortality review²¹ to cancer registries found that in decedents with intellectual disabilities and cancer, more than a third (35%; n=162) had cancer diagnosed via emergency presentations with almost half (45%; n=228) of cancers at stage IV when diagnosed²². In the same study, for colorectal cancers where pre-emptive screening was available, 43% died before reaching the colorectal screening age threshold. The findings of this study cited the absence of contemporary data about cancer in this population as being a particular issue.

Data about the prevalence and incidence of cancer diagnosis and mortality among people with intellectual disability are currently inconclusive. To understand how often people with an intellectual disability are diagnosed with cancer, what sub types of cancer they are diagnosed with and die from will be estimated in this review. Although a relatively recent phenomenon in evidence synthesis, prevalence and incidence systematic review and meta-analysis is an emerging methodology²³. Such reviews are becoming increasingly important as they can yield useful information on the burden of disease, illustrate trends, and inform geographical distributions of disease^23,24. This information is useful and important to help shape the national and international landscape, particularly where there are clearly gaps in the epidemiological data. From a national level, The Irish National Cancer Strategy (2017–2026)²⁵ has identified that the National Cancer Control Programme (NCCP) needs to focus on raising ‘cancer awareness and prevention initiatives’ and ‘prioritise disadvantaged populations and hard-to-reach groups’ (p.44). The cornerstone of the strategy outlines that early diagnosis will alter the landscape of cancer in Ireland by reducing mortality and improving survival. Nonetheless, such evidence is lacking in this population.

This proposed review and meta-analysis is part of a larger study that is being established called ‘The CANDID Study’. The CANDID study aims to explore CANcer incidence, prevalence, Diagnosis, treatment, risk factors and outcomes in older adults with Intellectual Disabilities in Ireland using longitudinal data from The Intellectual Disability Supplement to the Irish Longitudinal Study on Ageing (IDS-TILDA)²⁶. IDS-TILDA was established as a supplement to the Irish Longitudinal Study on Ageing (TILDA)²⁷. The ability to use descriptive and longitudinal methods to examine cancer in older adults with intellectual disabilities will provide information critical to the provision of cancer care and the development of national guidance for this population which is lacking nationally and internationally. The findings from this review will, in part support the NCCP in revealing inequalities that may exist and highlight where there is an urgent need to tailor cancer screening and prevention approaches for individuals with intellectual disability in Ireland.

Aim of the protocol

To describe a protocol for a systematic review which will synthesise the available evidence on the prevalence and incidence of cancer in adults with intellectual disability.

The objectives of the review are to:

1. estimate the prevalence and incidence of any cancer in adults with intellectual disability.
2. estimate the prevalence and incidence of sub types of cancers in adults with intellectual disability.
3. identify any trends in prevalence and incidence in subgroups of adults with intellectual disability based on i) gender (male versus female), ii) age (18–39 years and 40 years and older), and iii) severity of intellectual disability (mild, moderate, severe and profound)

The protocol was methodologically designed using JBI guidance for Systematic reviews of prevalence and incidence²⁸ and the PRISMA-P (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols)²⁹ guidelines. The protocol is registered at the International Prospective Register of Systematic Reviews (PROSPERO; registration number: CRD42023423584). Supplementary files are hosted on Open Science Framework (OSF) and are available here.

Methods

Eligibility criteria

Types of studies. This review will include studies that are observational (retrospective and cross sectional), and/or longitudinal with published baseline data that have estimated or presented data on the prevalence or incidence of cancer in adults with intellectual disability. This review will consider cohort studies that yield estimates of incidence while cross-sectional studies that yield estimates of prevalence^30,31. There will be no geographical, date or language restriction applied. Google translate will be used to screen abstracts of non-English language studies, and if included after screening, the full record will be translated by Google translate for full text review. Google translate has been found to be a viable and accurate tool for translating non-English reviews with over 91% accuracy agreement reported in a recent review³².

The numerator and denominator of the prevalence and incidence estimation fraction must be included in the studies. For example, for incidence the numerator is the number of new cases of cancer during a specified time interval and the denominator is the population at the start of the time interval. For prevalence, the numerator is the number of cases of cancer at a specified point of time and the denominator is the population at that time. If this data is not published or available, requests will be made to the corresponding author(s). Data from case reports, conference abstracts and experimental or quasi-experimental studies such as randomised controlled trials and controlled clinical trials, will not be included in this review.

Types of participants. Eligible studies will report on adults (≥ 18 years) of any gender, ethnicity or socioeconomic status who are identified as having intellectual disability. For the purposes of this review, intellectual disability will be accepted if the study reports that a participant has a) a standardised intelligence quotient test which was two Standard Deviations (SD) below the mean or lower, or b) they are receiving or eligible to receive services for people with intellectual disability due to adaptive or social functioning deficits in the jurisdiction the study was undertaken. Deficits should have occurred during the developmental period.

Given the challenge of identifying individuals with intellectual disability in studies of representative populations, frequently as a result of the absence of a generally accepted operational definition of intellectual disabilities³³, no a priori sampling size benchmark will be established and only studies which meet the inclusion criterion will be pooled for analysis. Studies that do not report the results for those with intellectual disability and those that focus on conditions where intellectual disability cannot be assumed, such as cerebral palsy, will be disregarded. Additionally, representation of specific subgroups of people with intellectual disability (e.g people with intellectual disability receiving cancer treatment in hospital) will also be excluded.

Outcome

The primary outcomes will be:

Prevalence of any type of cancer
Incidence of any type of cancer

Cancer types reported in the included studies will be diagnosed by an appropriately qualified medical professional with or without classification, or self-reported.

The secondary outcomes of interest will be:

Prevalence and Incidence of sub types of cancer

Sub types of cancer will include diagnosed cancers coded according to the International Classification of Disease (ICD) coding system at the time the study was undertaken in any of the following categories: C00-C97 Malignant neoplasms; D00-D09 In situ neoplasms; D10-D36 Benign neoplasms and D37-D48 Neoplasms of uncertain or unknown behaviour (An example of these cancers is provided under Extended data). For meta-analyses based on cancer sub-type, two or more studies will need to report on the same cancer type.

Search criteria, study selection and data extraction

A Subject Librarian (JEC) was engaged at the developmental stage of this review and with the primary author (MMcM) the Condition Context Population (CoCoPop)²³ framework was used to develop the search strategy (Table 1). This framework is commonly used for review questions focusing on prevalence. The search strategy was initially built using EMBASE (Elsevier) and then adapted for the other databases, as listed below. Database thesauri were reviewed for controlled language and synonyms. A keyword list was developed and adapted with additional input from the primary author. The search will utilise a combination of database specific control language and keywords (these will remain the same for each database), which will be combined with the OR Boolean operand. To increase the sensitivity of the search, NEAR proximity operators will be applied to the keyword search. The proximity will require cancer keywords appearing within 6 words of patient keywords with a proximity of 4 from prevalence. Each concept search will be run independently, and then combined with the AND operand to provide the final set of records for screening. The search strategy was peer-reviewed by two additional Subject Librarians¹ and the Peer Review of Electronic Search Strategies (PReSS) checklist to improve quality of the literature search was used³⁴.

Table 1. CoCoPop for the proposed research questions.

Condition	Cancer
Context	Prevalence or incidence
Population	Adults with intellectual disability

The search is comprised of two key concepts: Prevalence/Incidence of Cancer AND Intellectual Disability.

Electronic database searching. Systematic searches will be undertaken in Embase (Elsevier; 1947-), MEDLINE (EBSCO; 1879-), CINAHL Ultimate (EBSCO; 1937-), PsycINFO (EBSCO; 1967-) and Web of Science – Core Collection (Clarivate; 1945-). No limits or filters will be placed on the search. Each database will be searched from inception to the search date. The reference lists from included full-text articles will be hand searched and forward citation searching will be undertaken.

The EMBASE search strategy is provided in Table 2.

Table 2. Search string for electronic database Embase.

Context & Condition	#1	‘cancer patient’/exp OR ('neoplasm'/exp AND 'patient'/exp) AND 'prevalence'/de
	#2	(oncolog* OR cancer* OR neoplasm* OR malign* OR carcin) NEAR/6 (patient OR client* OR individual* OR person* OR people) NEAR/4 (prevalen OR occur* OR incidenc*)
	#3	#1 OR #2
Population	#4	'mentally disabled person'/exp OR 'mental deficiency'/exp OR 'intellectual impairment'/exp OR 'cognitive defect'/exp
	#5	‘Intellectual Disabil’:ab,ti OR ‘Intellectually disabled’:ab,ti OR ‘mentally disabled’:ab,ti OR ‘mental disabil’ :ab,ti OR ‘Intellectual Development Disorder’:ab,ti OR ‘mental handicap’:ab,ti OR ‘mentally handicapped’: ab,ti OR ‘mentally impaired’:ab,ti OR ‘mental impairment’:ab,ti OR ‘intellectual impairment’:ab,ti OR ‘developmental disabil’:ab,ti OR ‘mental defici’:ab,ti OR ‘intellectual retard’:ab,ti OR ‘mental retard’: ab,ti OR ‘mentally retarded’:ab,ti OR ‘intellectually challenged’:ab,ti OR ‘intellectually deficient’:ab,ti OR ‘intellectually handicapped’:ab,ti OR ‘intellectually impaired’:ab,ti OR ‘intellectually retarded’:ab,ti OR ‘mentally challenged’:ab,ti OR ‘mentally defici’:ab,ti OR ‘cognitive disab*’:ab,ti
	#6	#4 OR #5
Final	#7	#3 AND #6

Grey and other literature. In addition to the core database search, supplementary databases searches will be run. These will include but are not limited to Global Index Medicus (WHO), Cochrane Library, British Nursing Index and Proquest Dissertations and Theses. Grey Literature searching will be undertaken in national and institutional repositories, search engines, including Google Scholar and relevant health and intellectual disability websites. All relevant articles will be added to Covidence for screening. All results will be reported into a spread sheet and added as a supplementary file to the final publication for transparency.

Software. Covidence will be used for screening and EndNote X20 by PDF Tron™ Systems Inc will be used to as a bibliography manager. Review Manager 5.4 and MetaXL software will be used for meta-analysis.

Study screening and selection. All results from each database will be exported into EndNote 20 and an initial deduplication will occur using the software. The resultant articles will then be exported for title and abstract screening into Covidence. To ensure that the eligibility criteria will be applied consistently by each of the screeners (MMcM and AW) a pilot test on a sample of 20 records will be undertaken initially, with screening congruency and understanding assessed via discussion and consensus.

Two reviewers (MMcM and AW) will independently screen all retrieved records against the review’s inclusion on i) titles and abstracts initially and then, for those forwarded after title/abstract screening on ii) full text. Disagreements, if any arise, will be discussed between MMcM and AW, and if no consensus can be reached, the matter will be referred to MMcC, who will make the final decision. This procedure will be carried out during each phase of the screening process. The screening and selection process for the study will be reported in accordance with the (PRISMA) 2020 updated guideline for reporting systematic reviews³⁵, and a PRISMA flow diagram will be generated.

Study quality and risk of bias assessment. A modified version of the JBI Critical Appraisal Checklist for Studies Reporting Prevalence Data will be used to evaluate the included studies' methodological quality and establish the degree to which bias was addressed in the study's design, conduct, and analysis²³. This is a nine-question tool from the Joanna Briggs Institute that addresses the: appropriateness of the sampling frame and study participants; the adequacy of the sample size; the description of study subjects and setting; sufficiency of data analysis; validity of identification of condition; reliable measurement of condition; appropriate statistical analysis; and, response rate. For each question there is a ‘yes’, ‘no’, ‘unclear’ or ‘not applicable’ response. Two reviewers (MMcM & AW) will independently determine the quality of each included study where ‘yes’ and ‘not applicable’ are scored ‘2’, unclear scored ‘1’‘ and ‘no’ scored ‘0’. This will leave a range of scores of ‘0-18’ with 18 being the highest quality. If MMcM or AW have any disagreements in determining quality, this will be resolved through discussion. However, if consensus cannot be achieved a third reviewer (MMcC) will be requested to make the final decision. The final quality assessment score for each included study will be reported along with the overall median and IQR quality assessment scores.

Data extraction. Data from the included studies (black and grey literature) will be extracted using a pre-designed data extraction form. A supplementary data extraction file in Microsoft Excel is available in OSF under Extended data. The extraction form will be piloted on five studies to make any refinements and finalised by MMcM and AW. Data will be extracted by MMcM and AW will undertake checks on half of the extracted studies. If there are major discrepancies identified all the extracted records will be reviewed. Extracted items will include: Authors and year; Grey or black literature; Country of study; Study aim; Sample characteristics; Sample origin; Age range (mean (SD); median); Gender (%); Degree of intellectual disability mild, moderate, severe or profound (%); Method of cancer diagnosis; Subtype of cancer(s) as per ICD-Classification system; Death (%); Cancer cases n; Sample size N; Cancer prevalence % (95% CI) and Cancer prevalence % (95% CI). Where data is not presented or missing in the research study the research team will contact the corresponding author(s) to request this. A cut off time frame of 3 weeks set with a reminder sent after one week. If the corresponding author(s) do not respond within these parameters, their study will be excluded from the review.

Data analysis and synthesis

It is important to highlight that there is no gold standard for how data analysis in prevalence and incidence systematic reviews should be performed and reported. However, where achievable, meta-analyses will be conducted using Review Manager 5.4 for pairwise comparisons and MetaXL will be used to pool overall incidence and prevalence. Following JBI guidance, if meta-analysis is not possible, narrative synthesis will be conducted as the primary mechanism of data synthesis with tables, graphs and figures presenting the results of the prevalence and the incidence of cancer and subtypes of cancer³⁶. Individual study data will be pooled using the DerSimonian-Laird proportion method³⁷ and a random effects meta-analysis will be undertaken^36,38. Following guidance from the JBI and Cochrane Handbook for Systematic Reviews, meta-analysis of incidence and prevalence data of cancer and cancer subtypes will be undertaken separately. The Standard Error (SE) of the incidence and/or prevalence can be determined using the numerator and denominator of the prevalence and incidence estimation fractions. Using Forest plots, separated and pooled incidence and prevalence along with 95% confidence intervals will be plotted. Values of p < .05 will be considered statistically significant and results will be reported in accordance with PRISMA guidelines³⁵. The Q-statistic test (to inform about the presence of heterogeneity) and I2 statistic (to quantify the degree of heterogeneity), and their related 95% CIs, will be calculated to determine statistical heterogeneity of the incidence and prevalence values in the included studies³⁹. Following Guidance from Higgins et al. (2003)⁴⁰ the threshold for interpreting the degree of heterogeneity will follow these parameters:

▪ 0% to 40%: might not be important
▪ 30% to 60%: may represent moderate heterogeneity
▪ 50% to 90%: may represent substantial heterogeneity
▪ 75% to 100%: considerable heterogeneity

Where there is 60% or more heterogeneity, these studies will not be included in meta-analysis. Additionally, where there are at least ten studies included in the meta-analysis, funnel plots will be used to make a visual assessment of whether small-study effects are present.

Sensitivity analysis will also be undertaken. All sensitivity analysis will be reported in summary tables and made available as a supplementary file to accompany the completed systematic review.

Potential influence on prevalence and incidence estimates will be explored using sensitivity and subgroup analyses as follows:

Sensitivity analyses will be conducted based on

i) study quality/risk of bias, with studies of QA scores outside of the upper quartile excluded from the analysis
ii) study design, with estimates of cancer prevalence from retrospective and prospective studies analysed separately to assess variation based on study design
iii) geographical region, based on study location and low-income countries, middle income countries and high-income countries

The variation in the prevalence and incidence estimates, where sufficient data are reported in the included studies, will be explored based on subgroup analyses of:

i) gender: male versus females
ii) age: 18–39 years and 40 years and older
iii) severity of intellectual disability (mild versus moderate, mild versus severe, mild vs profound, moderate versus severe, moderate versus profound and severe versus profound)

Study status

JEC and MMcM are currently in the process of undertaking the literature search.

Patient and public involvement

Engagement with knowledge users and patient and public involvement (PPI) involving people with intellectual disabilities themselves has been central to the development of the ‘The CANDID Study’. The research team consulted with Trinity College Dublin PPI Ignite Office and spoke with people with intellectual disabilities and their family members. This has shaped the development of this systematic review protocol through identifying and prioritising the research question. Patient and public involvement will be integrated throughout the course of the study.

Discussion

This planned review and meta-analysis will explore prevalence and incidence of cancer in adults with intellectual disability. As there is limited contemporary data about cancer in this population, this review will provide valuable information to help understand how common cancer is in adults with an intellectual disability and what type of cancers adults with an intellectual disability are being diagnosed with. Such information on cancer can be used to help target cancer inequalities that are believed to exist in this population and to improve outcomes.

Dissemination of findings

The findings from this review will be submitted for publication in an Open Access cancer related health journal and be presented at national and international conferences.

The findings of this review will be used to inform the NCCP about the prevalence and incidence of cancers and trends of cancer in adults with intellectual disability. It will be used to help reach ‘marginalised and hard to reach groups’ aligned with the Irish Cancer Strategy²⁵.

Conclusion

Following the JBI Systematic reviews of prevalence and incidence²⁸ and the PRISMA-P (Preferred Reporting Items for Systematic Reviews and Meta-Analyses)²⁹, this systematic review protocol describes the review methodology, eligibility criteria, methods of determining data quality, method for screening research papers for inclusion, methods of data extraction and the process for conducting data synthesis and meta-analysis to investigate the prevalence and incidence of cancer in adults with intellectual disability. It is believed this review will help synthesize the available evidence to identify cancer burden at specific points in time and over different points of time. It is anticipated that this review will help address the inequities that exist in the understanding of cancer and that the provision of cancer services that need to be delivered to this population

Data availability

Extended data

OSF: Prevalence and incidence of cancer amongst adults with intellectual disability: a systematic review and meta-analysis. DOI 10.17605/OSF.IO/RUAQ5

This project contains the following extended data:

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).

Reporting guidelines

OSF: Prevalence and incidence of cancer amongst adults with intellectual disability: a systematic review and meta-analysis. DOI 10.17605/OSF.IO/RUAQ5

Footnotes

¹ Greg Sheaf, M.A. Subject Librarian , The Library of Trinity College Dublin and David Mockler , M.A. Subject Librarian , The Library of Trinity College Dublin.

Faculty Opinions recommended

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29. Shamseer L, Moher D, Clarke M, et al.: Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015; 350: g7647. PubMed Abstract | Publisher Full Text
30. Dekkers OM, Vandenbroucke JP, Cevallos M, et al.: COSMOS-E: Guidance on conducting systematic reviews and meta-analyses of observational studies of etiology. PLoS Med. 2019; 16(2): e1002742. PubMed Abstract | Publisher Full Text | Free Full Text
31. Mann CJ: Observational research methods. Research design II: cohort, cross sectional, and case-control studies. Emerg Med J. 2003; 20(1): 54–60. PubMed Abstract | Publisher Full Text | Free Full Text
32. Jackson JL, Kuriyama A, Anton A, et al.: The Accuracy of Google Translate for Abstracting Data From Non-English-Language Trials for Systematic Reviews. Ann Intern Med. 2019; 171(9): 677–9. PubMed Abstract | Publisher Full Text
33. Fox MH, Bonardi A, Krahn GL: Expanding public health surveillance for people with intellectual and developmental disabilities in the United States. Int Rev Res Dev Disabil. 2015; 48(4): 73–114. PubMed Abstract | Free Full Text
34. McGowan J, Sampson M, Salzwedel DM, et al.: PRESS Peer Review of Electronic Search Strategies: 2015 Guideline Statement. J Clin Epidemiol. 2016; 75: 40–6. PubMed Abstract | Publisher Full Text
35. Page MJ, McKenzie JE, Bossuyt PM, et al.: The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021; 372: n71. PubMed Abstract | Publisher Full Text | Free Full Text
36. Aromataris E, Munn Z: JBI Manual for Evidence Synthesis. JBI, 2020. Publisher Full Text
37. DerSimonian R, Laird N: Meta-analysis in clinical trials. Control Clin Trials. 1986; 7(3): 177–88. PubMed Abstract | Publisher Full Text
38. Higgins JP, Thomas J, Chandler J, et al.: Cochrane handbook for systematic reviews of interventions. John Wiley & Sons; 2019. Reference Source
39. Huedo-Medina TB, Sánchez-Meca J, Marin-Martinez F, et al.: Assessing heterogeneity in meta-analysis: Q statistic or I² index? Psychol Methods. 2006; 11(2): 193–206. PubMed Abstract | Publisher Full Text
40. Higgins JP, Thompson SG, Deeks JJ, et al.: Measuring inconsistency in meta-analyses. BMJ. 2003; 327(7414): 557–60. PubMed Abstract | Publisher Full Text | Free Full Text

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Version 2

VERSION 2 PUBLISHED 13 Sep 2023

Author details Author details

Martin McMahon
Roles: Conceptualization, Data Curation, Investigation, Methodology, Project Administration, Writing – Original Draft Preparation, Writing – Review & Editing

Andrew Wormald
Roles: Methodology, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Jessica Eustace-Cook
Roles: Data Curation, Methodology, Software, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Mary McCarron
Roles: Conceptualization, Methodology, Resources, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Philip McCallion
Roles: Conceptualization, Methodology, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Valerie Smith
Roles: Methodology, Software, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Competing interests

No competing interests were disclosed.

Grant information

This research was funded by the Health Research Board ‘IDS-TILDA-2021-001’.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Article Versions (2)

version 2

Revised

Published: 02 Feb 2024, 6:51

https://doi.org/10.12688/hrbopenres.13740.2

version 1

Published: 13 Sep 2023, 6:51

https://doi.org/10.12688/hrbopenres.13740.1

© 2023 McMahon M et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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McMahon M, Wormald A, Eustace-Cook J et al. Prevalence and incidence of cancer amongst adults with intellectual disability — a systematic review and meta-analysis protocol [version 1; peer review: 1 approved, 1 approved with reservations]. HRB Open Res 2023, 6:51 (https://doi.org/10.12688/hrbopenres.13740.1)

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PUBLISHED 13 Sep 2023

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Reviewer Report 27 Nov 2023

Owen Doody, Department of Nursing and Midwifery, North Bank Campus, University of Limerick (UL), Limerick, Ireland

Approved

https://doi.org/10.21956/hrbopenres.15030.r36980

This is a clear and relevant protocol with minor comments and rational needed.

General point using people with intellectual disability and people with intellectual disabilities - can one term be used consistently throughout the paper.

Introduction - cancer under detected and die before reaching screening age mentioned -- I am wondering is there evidence of a post mortem being performed and how this might relate to existing figures? Introduction ends with the proposed review and links to IDS-TILDA and could be relooked at in terms of how related to evidence presented in the introduction and the gap that exists and will be filled by this review and acknowledge part of a wider study.

Aim - age group 18-39 and 40+ given the age profile of ID should consideration be given to subdividing the 40+ age group.

Methods - why not under 18 given Down’s Syndrome and leukemia justify adults only versus a life approach? Why use a modified version of the JBI critical appraisal tool and what modification are you using or is it a previous modification you are choosing? Also - intellectual disability will be accepted if the study reports that a participant has a standardised intelligence quotient test which was two Standard Deviations (SD) below the mean or lower, or they are receiving or eligible to receive services for people with intellectual disability due to adaptive or social functioning deficits in the jurisdiction the study was undertaken and deficits should have occurred during the developmental period - how will you address / intelligence quotient test or definition of ID in papers or will you accept paper that identify population as having an ID even if a definition or IQ is not reported also are you assuming deficits should have occurred during the developmental period if person is receiving a service - greater clarity here is required.

The protocol is overall described well and the planned work is important and relevant.

Is the rationale for, and objectives of, the study clearly described?

Yes
Is the study design appropriate for the research question?

Yes
Are sufficient details of the methods provided to allow replication by others?

Yes
Are the datasets clearly presented in a useable and accessible format?

Yes

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Intellectual disability

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

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Author Response 23 May 2024

Martin McMahon, School of Nursing & Midwifery, The University of Dublin Trinity College, Dublin, D02 PN40, Ireland

23 May 2024

Author Response

Thank you for reviewing this protocol and for your valuable insights which we will give due consideration..
'People with intellectual disability' has been replaced with 'people with intellectual disabilities' for ... Continue reading Thank you for reviewing this protocol and for your valuable insights which we will give due consideration..
'People with intellectual disability' has been replaced with 'people with intellectual disabilities' for consistency.
The presence of an intellectual disability will be assessed and verified for each individual paper.
Further subdivision of the 40+ age group may be investigated. This review will not include children, only adults >18years.
Thank you for reviewing this protocol and for your valuable insights which we will give due consideration..
'People with intellectual disability' has been replaced with 'people with intellectual disabilities' for consistency.
The presence of an intellectual disability will be assessed and verified for each individual paper.
Further subdivision of the 40+ age group may be investigated. This review will not include children, only adults >18years.
Competing Interests: No competing interests are present Close
Report a concern
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COMMENTS ON THIS REPORT

Author Response 23 May 2024

Martin McMahon, School of Nursing & Midwifery, The University of Dublin Trinity College, Dublin, D02 PN40, Ireland

23 May 2024

Author Response

Thank you for reviewing this protocol and for your valuable insights which we will give due consideration..
'People with intellectual disability' has been replaced with 'people with intellectual disabilities' for ... Continue reading Thank you for reviewing this protocol and for your valuable insights which we will give due consideration..
'People with intellectual disability' has been replaced with 'people with intellectual disabilities' for consistency.
The presence of an intellectual disability will be assessed and verified for each individual paper.
Further subdivision of the 40+ age group may be investigated. This review will not include children, only adults >18years.
Thank you for reviewing this protocol and for your valuable insights which we will give due consideration..
'People with intellectual disability' has been replaced with 'people with intellectual disabilities' for consistency.
The presence of an intellectual disability will be assessed and verified for each individual paper.
Further subdivision of the 40+ age group may be investigated. This review will not include children, only adults >18years.
Competing Interests: No competing interests are present Close
Report a concern

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Reviewer Report 10 Oct 2023

Trine Allerslev Horsbøl, National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark

Approved with Reservations

https://doi.org/10.21956/hrbopenres.15030.r36134

Thanks to the authors for submitting this protocol. In a detailed way, they describe the rationale and methodology of a review on prevalence and incidence of cancer among adults with intellectual disability.

I think the planned work is extremely important and relevant, and I am looking forward to seeing and using the results.

I have some minor comment to the protocol.

Overall I suggest that the authors make a thorough linguistic revision of the paper. As it is now, there are a lot of long sentences, and a lot of commas are missing. Further, there are several words that should be combined with a hyphen. For example age-related, disease-related, under-detection etc. Also, in some sentences, words are missing, e.g.Two reviewers (MMcM and AW) will independently screen all retrieved records against the review’s inclusion criteria. Or wrong: Cancer prevalence % (95% CI) and Cancer prevalence % (95% CI) and Where data is not presented or missing in the research study (delete research).
It is stated that eligible studies have published baseline data that have estimated baseline data on incidence and prevalence of cancer. Incidence can not be estimated from baseline data, as it includes follow-up. I therefore suggest that you reconsider this inclusion criteria.
Inclusion criteria of study designs needs to be sharpened. A retrospective design is most often a case-control study, and this design is not relevant when estimating prevalence or incidence. Prevalence is most often estimated in a cross-sectional study, and incidence is measured in a cohort study. Thus, in my point of view, these two designs are the relevant designs to consider.
Please specify, if you only consider studies that report incidence proportions (that is the frequency measure that is described as it is now, with number of persons in the denomoniator). Do you exclude studies that report incidence rates? (new cases pr. number of person-years).
You only consider studies, where intellectual desibility is defined through a standardised intelligence quotient or receiving services for people with intellectual disability. What about diagnoses? For example on intellectual disability, Down Syndrome etc.? This is often the way that people with intellectual disabilities are identified in register-based studies.
I think you should clarify the same for cancer diagnoses. Is it okay with cancer cases registered in Cancer Registers?
You state that if no consensus can be reached, the matter will be referred to MMcC, who will make the final decision. Have you considered including a third person in these discussions instead?

Is the rationale for, and objectives of, the study clearly described?

Yes
Is the study design appropriate for the research question?

Yes
Are sufficient details of the methods provided to allow replication by others?

Yes
Are the datasets clearly presented in a useable and accessible format?

Not applicable

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Cancer, intellectual disability, diabetes, epidemiology, systematic reviews, public health

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

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Author Response 23 May 2024

Martin McMahon, School of Nursing & Midwifery, The University of Dublin Trinity College, Dublin, D02 PN40, Ireland

23 May 2024

Author Response

Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to ... Continue reading Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to improve readability, including the shortening of sentences, addition of commas and additional hyphenation
- the sentence on 'baseline data' has been removed
- Inclusion criteria for study designs have been revised
- Incidence 'rates and proportions' is specifically included
- An additional sentence has been added to clarify the intellectual disability studies.
- Cancer registers has been included as a source
- A third reviewer has come on board for the project (LL) who will review articles and a fourth reviewer will arbitrate in case of any disputes.
Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to improve readability, including the shortening of sentences, addition of commas and additional hyphenation
- the sentence on 'baseline data' has been removed
- Inclusion criteria for study designs have been revised
- Incidence 'rates and proportions' is specifically included
- An additional sentence has been added to clarify the intellectual disability studies.
- Cancer registers has been included as a source
- A third reviewer has come on board for the project (LL) who will review articles and a fourth reviewer will arbitrate in case of any disputes.
Competing Interests: No competing interests. Close
Report a concern
Respond or Comment

COMMENTS ON THIS REPORT

Author Response 23 May 2024

Martin McMahon, School of Nursing & Midwifery, The University of Dublin Trinity College, Dublin, D02 PN40, Ireland

23 May 2024

Author Response

Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to ... Continue reading Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to improve readability, including the shortening of sentences, addition of commas and additional hyphenation
- the sentence on 'baseline data' has been removed
- Inclusion criteria for study designs have been revised
- Incidence 'rates and proportions' is specifically included
- An additional sentence has been added to clarify the intellectual disability studies.
- Cancer registers has been included as a source
- A third reviewer has come on board for the project (LL) who will review articles and a fourth reviewer will arbitrate in case of any disputes.
Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to improve readability, including the shortening of sentences, addition of commas and additional hyphenation
- the sentence on 'baseline data' has been removed
- Inclusion criteria for study designs have been revised
- Incidence 'rates and proportions' is specifically included
- An additional sentence has been added to clarify the intellectual disability studies.
- Cancer registers has been included as a source
- A third reviewer has come on board for the project (LL) who will review articles and a fourth reviewer will arbitrate in case of any disputes.
Competing Interests: No competing interests. Close
Report a concern

Comments on this article Comments (0)

Version 2

VERSION 2 PUBLISHED 13 Sep 2023

Open Peer Review

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	1	2
Version 2 (revision) 02 Feb 24	read
Version 1 13 Sep 23	read	read

Trine Allerslev Horsbøl, University of Southern Denmark, Copenhagen, Denmark
Owen Doody, University of Limerick (UL), Limerick, Ireland

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Reviewer Report

8 Views

07 Feb 2024 | for Version 2

Trine Allerslev Horsbøl, National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark

8 Views Cite this report Responses(0)

Approved

Congratulations to the authors on their great job. I have no further comments, and I am looking forward to reading the results of the systematic review.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Cancer, intellectual disability, diabetes, epidemiology, systematic reviews, public health

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Respond to this report

Responses (0)

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Reviewer Report

17 Views

27 Nov 2023 | for Version 1

Owen Doody, Department of Nursing and Midwifery, North Bank Campus, University of Limerick (UL), Limerick, Ireland

17 Views Cite this report Responses(1)

Approved

Is the rationale for, and objectives of, the study clearly described?

Yes
Is the study design appropriate for the research question?

Yes
Are sufficient details of the methods provided to allow replication by others?

Yes
Are the datasets clearly presented in a useable and accessible format?

Yes

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Intellectual disability

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Respond to this report

Responses (1)

Back to all reports

Reviewer Report

21 Views

10 Oct 2023 | for Version 1

Trine Allerslev Horsbøl, National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark

21 Views Cite this report Responses(1)

Approved With Reservations

Overall I suggest that the authors make a thorough linguistic revision of the paper. As it is now, there are a lot of long sentences, and a lot of commas are missing. Further, there are several words that should be combined with a hyphen. For example age-related, disease-related, under-detection etc. Also, in some sentences, words are missing, e.g.Two reviewers (MMcM and AW) will independently screen all retrieved records against the review’s inclusion criteria. Or wrong: Cancer prevalence % (95% CI) and Cancer prevalence % (95% CI) and Where data is not presented or missing in the research study (delete research).
It is stated that eligible studies have published baseline data that have estimated baseline data on incidence and prevalence of cancer. Incidence can not be estimated from baseline data, as it includes follow-up. I therefore suggest that you reconsider this inclusion criteria.
Inclusion criteria of study designs needs to be sharpened. A retrospective design is most often a case-control study, and this design is not relevant when estimating prevalence or incidence. Prevalence is most often estimated in a cross-sectional study, and incidence is measured in a cohort study. Thus, in my point of view, these two designs are the relevant designs to consider.
Please specify, if you only consider studies that report incidence proportions (that is the frequency measure that is described as it is now, with number of persons in the denomoniator). Do you exclude studies that report incidence rates? (new cases pr. number of person-years).
You only consider studies, where intellectual desibility is defined through a standardised intelligence quotient or receiving services for people with intellectual disability. What about diagnoses? For example on intellectual disability, Down Syndrome etc.? This is often the way that people with intellectual disabilities are identified in register-based studies.
I think you should clarify the same for cancer diagnoses. Is it okay with cancer cases registered in Cancer Registers?
You state that if no consensus can be reached, the matter will be referred to MMcC, who will make the final decision. Have you considered including a third person in these discussions instead?

Is the rationale for, and objectives of, the study clearly described?

Yes
Is the study design appropriate for the research question?

Yes
Are sufficient details of the methods provided to allow replication by others?

Yes
Are the datasets clearly presented in a useable and accessible format?

Not applicable

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Cancer, intellectual disability, diabetes, epidemiology, systematic reviews, public health

Respond to this report

Responses (1)

Author Response

23 May 2024

Martin McMahon, School of Nursing & Midwifery, The University of Dublin Trinity College, Dublin, D02 PN40, Ireland

Thank you very much for reviewing this protocol and for your insightful feedback, which has been given due consideration as follows:
- the paper has been reviewed and adapted to improve readability, including the shortening of sentences, addition of commas and additional hyphenation
- the sentence on 'baseline data' has been removed
- Inclusion criteria for study designs have been revised
- Incidence 'rates and proportions' is specifically included
- An additional sentence has been added to clarify the intellectual disability studies.
- Cancer registers has been included as a source
- A third reviewer has come on board for the project (LL) who will review articles and a fourth reviewer will arbitrate in case of any disputes.

View more View less

Competing Interests

No competing interests.

Alongside their report, reviewers assign a status to the article:

Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested

Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.

Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions

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[28] 28. Munn Z, Moola S, Lisy K, et al.: Systematic reviews of prevalence and incidence. Joanna Briggs Institute reviewer’s manual [Internet] Adelaide: The Joanna Briggs Institute. 2017. Publisher Full Text

[29] 29. Shamseer L, Moher D, Clarke M, et al.: Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015; 350: g7647. PubMed Abstract | Publisher Full Text

[30] 30. Dekkers OM, Vandenbroucke JP, Cevallos M, et al.: COSMOS-E: Guidance on conducting systematic reviews and meta-analyses of observational studies of etiology. PLoS Med. 2019; 16(2): e1002742. PubMed Abstract | Publisher Full Text | Free Full Text

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[32] 32. Jackson JL, Kuriyama A, Anton A, et al.: The Accuracy of Google Translate for Abstracting Data From Non-English-Language Trials for Systematic Reviews. Ann Intern Med. 2019; 171(9): 677–9. PubMed Abstract | Publisher Full Text

[33] 33. Fox MH, Bonardi A, Krahn GL: Expanding public health surveillance for people with intellectual and developmental disabilities in the United States. Int Rev Res Dev Disabil. 2015; 48(4): 73–114. PubMed Abstract | Free Full Text

[34] 34. McGowan J, Sampson M, Salzwedel DM, et al.: PRESS Peer Review of Electronic Search Strategies: 2015 Guideline Statement. J Clin Epidemiol. 2016; 75: 40–6. PubMed Abstract | Publisher Full Text

[35] 35. Page MJ, McKenzie JE, Bossuyt PM, et al.: The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021; 372: n71. PubMed Abstract | Publisher Full Text | Free Full Text

[36] 36. Aromataris E, Munn Z: JBI Manual for Evidence Synthesis. JBI, 2020. Publisher Full Text

[37] 37. DerSimonian R, Laird N: Meta-analysis in clinical trials. Control Clin Trials. 1986; 7(3): 177–88. PubMed Abstract | Publisher Full Text

[38] 38. Higgins JP, Thomas J, Chandler J, et al.: Cochrane handbook for systematic reviews of interventions. John Wiley & Sons; 2019. Reference Source

[39] 39. Huedo-Medina TB, Sánchez-Meca J, Marin-Martinez F, et al.: Assessing heterogeneity in meta-analysis: Q statistic or I² index? Psychol Methods. 2006; 11(2): 193–206. PubMed Abstract | Publisher Full Text

[40] 40. Higgins JP, Thompson SG, Deeks JJ, et al.: Measuring inconsistency in meta-analyses. BMJ. 2003; 327(7414): 557–60. PubMed Abstract | Publisher Full Text | Free Full Text

Prevalence and incidence of cancer amongst adults with intellectual disability — a systematic review and meta-analysis protocol

Abstract

Keywords

Introduction

Aim of the protocol

Methods

Eligibility criteria

Outcome

Search criteria, study selection and data extraction

Table 1. CoCoPop for the proposed research questions.

Table 2. Search string for electronic database Embase.

Data analysis and synthesis

Study status

Patient and public involvement

Discussion

Dissemination of findings

Conclusion

Data availability

Extended data

Reporting guidelines

Footnotes

References

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Prevalence and incidence of cancer amongst adults with intellectual disability — a systematic review and meta-analysis protocol

Abstract

Keywords

Introduction

Aim of the protocol

Methods

Eligibility criteria

Outcome

Search criteria, study selection and data extraction

Table 1. CoCoPop for the proposed research questions.

Table 2. Search string for electronic database Embase.

Data analysis and synthesis

Study status

Patient and public involvement

Discussion

Dissemination of findings

Conclusion

Data availability

Extended data

Reporting guidelines

Footnotes

References

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Reviewer Reports

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