Keywords
Early diagnosis, Screening, Transactional data, Health informatics, Consumer behaviour, Scoping review
The early detection of many diseases is crucial for effective treatment, as it increases the likelihood of successful management and helps prevent or delay complications. However, early detection is often hampered by the asymptomatic nature of initial disease stages and delays in patients seeking care. In cancers such as ovarian, gastrointestinal, and haematological types, delays may result from self-management of non-specific symptoms with over-the-counter medications. Recent studies, such as the Cancer Loyalty Card Study (CLOCS), suggest that transactional data can reveal early self-medicating behaviours indicative of cancer. Despite this potential, a comprehensive understanding of the use of transactional data for early diagnosis across diseases is lacking.
This scoping review aims to systematically collate and analyse the literature on the use of transactional data for early detection of any disease, assessing its viability as a predictive tool.
The review will follow the Arksey and O’Malley methodological framework, with enhancements by Levac et al., and will be reported according to PRISMA-P and PRISMA-ScR guidelines. A comprehensive search will be conducted across databases including MEDLINE, Embase, Scopus, Web of Science, and the Cochrane Database of Systematic Reviews. The review will include studies that utilise transactional data to identify early signs of disease, focusing on both peer-reviewed articles and conference abstracts. The data will be thematically charted and synthesised to compare methodologies, disease types, types of transactional data used, key findings, and limitations.
By mapping the use of transactional data as a non-invasive tool for early detection, this review aims to inform and potentially transform approaches to screening and diagnosis. The findings will provide insights for healthcare professionals, researchers, and policymakers, supporting the development of targeted interventions that leverage transactional data for disease surveillance and early detection.
Early diagnosis, Screening, Transactional data, Health informatics, Consumer behaviour, Scoping review
See the authors' detailed response to the review by Paul A. Townsend
Many diseases begin with subtle symptoms, which can lead to delayed diagnoses that occur only after significant, sometimes irreversible, damage has been done. These late diagnoses are linked to lower survival rates and higher morbidity, highlighting the importance of early detection to improve patient outcomes.1–3 Early diagnosis refers to identifying a condition at a stage when interventions can prevent or minimise irreversible damage, thereby improving survival rates, reducing morbidity, and enhancing quality of life.1–3
However, the early detection of diseases presents substantial challenges. Many diseases in their early stages are asymptomatic or present with non-specific symptoms, which complicates timely diagnosis. Conditions such as cardiovascular diseases, renal diseases, and various forms of cancer exemplify this issue, where delays in seeking care are common due to the subtlety of early symptoms.4–6 These delays are often exacerbated by self-management behaviours, where individuals attempt to alleviate vague symptoms with over-the-counter (OTC) medications. While self-medication can temporarily mask symptoms, it may also obscure the early signs of more serious underlying conditions, such as malignancies.7,8
Recent studies, including the Cancer Loyalty Card Study (CLOCS), have explored the use of transactional data—specifically, the purchase of OTC medications—as a potential tool for early disease detection. These studies suggest that patterns in transactional data can reveal self-medicating behaviours that may be indicative of conditions like cancer, offering a novel and non-invasive method for early diagnosis.9 Beyond cancer, transactional data has also been used to enhance the detection of infectious disease outbreaks, such as Influenza, by tracking sales of specific OTC medication.10,11
The relevance of this approach is further supported by research showing that patients with certain cancers, such as ovarian, haematological, and gastrointestinal cancers, often delay seeking professional advice due to non-specific symptoms, which they manage with OTC medications.12–14 For example, a survey of over 1,500 women with ovarian cancer revealed that many attributed early symptoms to non-threatening causes such as irregular menstrual cycles, menopause, or aging, leading to delayed diagnosis.14 Additionally, focus group studies have demonstrated that these women had higher purchases of specific medications prior to diagnosis compared to healthy controls, indicating a potential pattern that could be leveraged for earlier detection.15
The potential for using transactional data in medical research is further supported by regulatory frameworks like the General Data Protection Regulation (GDPR), which grants patients the right to access their personal data, including transaction records.16 This regulation could facilitate the ethical use of consumer transactional data for medical research, provided that safeguards such as the ability to withdraw consent, data security measures, and transparency in data management are maintained.15
Given these developments, transactional data, such as purchase histories of OTC medications, has emerged as a promising avenue for the early detection of cancer and other diseases.9–11 The ability to detect early warning signs through consumer purchasing patterns represents a novel, non-invasive diagnostic approach that could significantly improve early diagnosis strategies. However, the existing literature on this topic is fragmented, with studies varying widely in design, disease focus, and outcomes. To date, there has been no comprehensive synthesis that could clarify the overall efficacy of using transactional data for disease detection and its potential applications in public health and clinical practice.
The aim of this scoping review is to provide a detailed overview of how transactional data can be used in the early detection of disease. This review intends to map the range, scope, and nature of the existing research, providing critical insights into the feasibility of utilising such data to enhance early diagnosis strategies.
The specific objectives include:
1. to identify all peer-reviewed articles which describe the use transactional data for early detection, cataloguing them according to methodology, disease type and data type;
2. to report, in the case of observational and interventional studies, the population characteristics, the event horizon studied, and how the transactional data and disease diagnosis data were operationalised;
3. to quantify, where the published data allow, the predictive power of the disease signal identified in the transactional data, by calculating the implied positive predictive value;
4. to discuss the logistical, legal and ethical challenges related to the use of transactional data in disease screening and early detection reported by the authors of the primary studies.
5. to conduct this review in two phases, the first phase will focus specifically on the early detection of cancer, while the second phase will broaden the scope to include the early detection of any disease.
We will conduct a scoping review in accordance the Arksey and O’Malley framework enhanced by Levac et al.17 The protocol will adhere to the PRISMA-P reporting guidelines and will be pre-registered on the Open Science Framework. The results will be reported following the PRISMA-ScR guideline.18 Supplementary files and relevant datasets will be made available via the Open Science Framework.19
The review will include studies that use transactional data for early detection of diseases. Eligible studies must specifically address the use of transactional data, such as loyalty card purchases or OTC medication sales, with incident disease or disease recurrence as an outcome, regardless of the disease type. Studies from all geographical locations will be considered.
Since our aim is to describe the scope of the literature, all article types will be eligible for inclusion: interventional studies, observational studies, qualitative studies, review articles, letters and editorials will all be included. Both peer-reviewed articles (including doctoral theses) and conference abstracts will be included. We will exclude studies that do not focus on transactional data or are not concerned with diagnosis as an outcome.
In Phase 1, the databases to be searched include MEDLINE, Embase, Scopus, Web of Science, and the Cochrane Database of Systematic Reviews. In Phase 2, additional sources such as CINAHL, ProQuest Dissertations and Theses Global (PQDT Global), three clinical trial registries (ClinicalTrials.gov, EU Clinical Trials Register, and International Standard Randomised Controlled Trial Number), and two systematic review registries (PROSPERO and Joanna Briggs Institute) will also be searched.
The search strategy, developed with an information specialist, will combine keywords and subject headings related to the themes of “transactional data” and “early detection”. To ensure thorough coverage, the strategy will also incorporate synonyms and related terms such as “purchase data,” “loyalty card data,” “retail data,” and “consumer behaviour data.” The detailed search strategies for both phases are available via the Open Science Framework in Appendix 1 – Search Strategy: https://doi.org/10.17605/OSF.IO/ZRJT5.20 Based on pilot searches, it is anticipated the number of papers to be screened in Phase 1 will be less than 20,000, while the number of papers to be screened in Phase 2 is expected to be over 100,000. References of included studies will be reviewed to identify additional relevant works.
Two reviewers will independently screen titles and abstracts for eligibility using Rayyan, a software that designed to facilitate efficient screening of abstracts and titles.21 Reviewers will follow the screening algorithm ( Table 1) to determine included studies and excluded studies. Full-text screening will follow for potentially relevant studies. Discrepancies will be resolved through discussion or consultation with a third reviewer. A PRISMA flow diagram will document the selection process. The screening algorithm, which will be piloted using a limited search of the MEDLINE database, is outlined on Open Science Framework: https://doi.org/10.17605/OSF.IO/ZRJT5.20
Given the high volume of articles anticipated in Phase 2, title and abstract screening may be assisted by an artificial intelligence tool. We will use Research Screener22 or Rayyan’s AI functionality. The validity of this approach will be assessed using the Phase 1 results (where human reviewers have already made decisions) as a gold standard. We will calculate the AI’s sensitivity (proportion of included articles correctly identified) and specificity. Only if sensitivity is ≥95% will we proceed with AI-assisted screening for Phase 2. In that case, two reviewers will independently verify all articles flagged for inclusion by the AI and a random 10% of excluded articles. Any disagreements will be resolved by a third reviewer. Regular calibration checks will be performed every 500 abstracts. The detailed approach will be outlined in a subsequent protocol akin to a previous study implementing a similar approach.22
A standardised form will be used to extract data from selected studies based on Table 2. Extracted data will include study characteristics (e.g. author, year, disease type), transactional data specifics (data sources, items tracked), methodology (e.g. data collection, analysis techniques), and key findings (e.g. disease symptoms identified, effectiveness of detection, and limitations).
This review aims to identify and catalogue peer-reviewed articles that utilise transactional data for early disease detection, categorising them based on methodology, disease type, and data type. For observational and interventional studies, it will report population characteristics, the time window between data collection and diagnosis (the ‘lookback period’ studied, and operationalisation of transactional and disease diagnosis data. Additionally, it will quantify the predictive power of the studied transactional data signal, when possible, by calculating the implied positive predictive value.
While scoping reviews do not typically require quality assessment, we will critically appraise included studies to inform the interpretation of findings. For observational studies of exposures (e.g., purchase patterns), we will use ROBINS-E; for non-randomised intervention studies, we will use ROBINS-I.23,24 However, we acknowledge that these tools require adaptation for transactional data research. We will therefore assess the following domain-specific biases: (1) Confounding: whether studies adjusted for socioeconomic status, healthcare access, comorbidities, and prior healthcare utilisation; (2) Selection bias: whether the transactional data source (e.g., loyalty card holders) is representative of the target population; (3) Information bias: validity of purchase data as a proxy for medication consumption (purchased ≠ ingested); (4) Temporal bias: whether the lookback period is appropriately aligned with disease natural history. We will not calculate a summary quality score but will present domain-level assessments in a narrative summary and a traffic-light table (green/yellow/red) for each included study. Meta-biases and confidence in cumulative evidence will not be reported since we are conducting a scoping review that does not focus on a single primary outcome.
The data synthesis will proceed through four steps. First, a bibliometric analysis will map the research landscape by categorising identified articles by methodology, disease type, and data type, providing a high-level overview of the field. Second, study details will be analysed, including population characteristics, study durations, and the operational definitions and uses of transactional and disease diagnosis data, using simple descriptive statistics and narrative approaches as appropriate. Third, where data are sufficient, we will quantify the implied positive predictive value (PPV) of the transactional data signal. For studies reporting sensitivity and specificity, we will calculate PPV = (sensitivity × prevalence) / [(sensitivity × prevalence) + ((1 − specificity) × (1 − prevalence))] using prevalence estimates from population-based cancer registries or epidemiological studies matched for age, sex, and region. For studies reporting odds ratios or hazard ratios, we will convert these to approximate PPVs. Where published data do not allow PPV calculation, we will narratively report the available measures of association (e.g., OR, HR, AUC) and explicitly state that PPV could not be derived. Results will be stratified by study design (case-control vs. cohort vs. cross-sectional), as PPV interpretation differs fundamentally across these designs. Finally, the review will discuss the logistical, legal, and ethical challenges highlighted in the studies, addressing the complexities of using transactional data in disease detection.
Handling of ethical and commercial considerations: We will systematically extract and report the following for each included study: (1) Ethical approval: whether the study reports obtaining ethics committee approval; (2) Data governance: any reported GDPR compliance, data anonymisation methods, patient consent procedures, or data withdrawal mechanisms; (3) Commercial conflicts: funding sources (e.g., retail companies, loyalty card providers, pharmaceutical firms) and author affiliations with commercial entities. Studies that use transactional data without documented ethical approval or patient consent will be flagged in the synthesis. Any potential outcome reporting bias associated with commercial funding will be discussed. This information will be presented in a separate table and considered when interpreting the strength of evidence.
Phase 1 (cancer only) – database searches and screening (Month 1–3), data extraction (Month 4); Phase 2 (all diseases) – database searches (Month 4), AI-assisted title/abstract screening (Months 5–7), full-text screening (Month 8), data extraction (Months 9–10), analysis and synthesis (Months 11–12), manuscript submission (Month 13).
This scoping review protocol presents a systematic approach to examining the use of transactional data in the early detection of diseases. It highlights key areas of interest, including the types of diseases studied, the nature of the data utilised, the methodologies employed, and the challenges encountered in this emerging field. The significance of this review lies in its potential to clarify the utility of transactional data—such as loyalty card purchases and OTC medication sales—as a tool for early diagnosis across a range of conditions.
A major strength of this protocol is its comprehensive and methodical approach to literature search and data extraction, ensuring that the review will thoroughly explore the landscape of research in this area. The inclusion of various study types and the systematic categorisation of findings by disease type, data type, and methodology will provide a broad and detailed overview of the current state of the field.
However, several limitations must be acknowledged. First, there is the issue of publication bias, where studies with negative or inconclusive results may not have been published, potentially skewing the literature. Additionally, language bias could limit the scope of this review, as studies published in languages other than English may be excluded. Another challenge arises from the need to synthesise a large and diverse body of literature into a coherent summary, which may overlook some nuances of individual studies.
A significant limitation specific to this area of research is the restricted access to raw transactional data. For example, in studies like the Cancer Loyalty Card Study (CLOCS), the raw data cannot be shared with other researchers due to privacy and legal constraints. This limitation directly impacts our ability to fully answer the research question, particularly concerning the detailed analysis of transactional patterns associated with early disease detection. While we can report on the scope of the literature in terms of publication details, publication type, methods, location, cancer type, and general descriptions of the datasets used, the lack of access to raw data means that our ability to assess the robustness of the findings reported in primary studies is inherently constrained. However, most primary studies are expected to provide sufficient descriptions of the datasets and methodologies used, allowing us to still draw meaningful insights into the use of transactional data for early diagnosis.
The findings of this review will be instrumental in shaping future research on the use of transactional data in disease detection. By identifying gaps in the existing literature and highlighting under-researched areas, this review will guide researchers towards optimal study designs and methodologies. Moreover, it will provide healthcare professionals with the latest insights into innovative tools for early detection, potentially leading to advancements in screening and diagnosis practices that could improve patient outcomes.
In addition, this review aims to contribute to the ongoing dialogue on the ethical and privacy concerns associated with the use of transactional data in medical research. By addressing these concerns, we hope to influence the development of guidelines that balance the potential health benefits of this research with the need to protect patient privacy and data security.
In conclusion, the proposed scoping review will provide valuable contributions to our understanding of the potential role of transactional data in early diagnosis. By mapping the research landscape, evaluating methodologies, synthesising key findings, and identifying gaps, this review will inform both current practices and future directions in disease detection research. Despite the limitations posed by the inaccessibility of raw data, this review will offer a comprehensive overview of how transactional data is currently being used and its potential to enhance early detection strategies, ultimately aiming to improve patient outcomes.
No data associated with this article since it is a research protocol and does not include associated datasets.
Datasets generated during research will be uploaded permanently on the Open Science Framework: Protocol of a Scoping Review on the Use of Transactional Data for Early Diagnosis (TRADED-ScR): https://doi.org/10.17605/OSF.IO/ZRJT5 under CC-By Attribution 4.0 International license.20
The full search strategy and PRISMA-P checklist are available via the Open Science Framework: Protocol of a Scoping Review on the Use of Transactional Data for Early Diagnosis (TRADED-ScR): https://doi.org/10.17605/OSF.IO/ZRJT5 under CC-By Attribution 4.0 International license.20
PRISMA-P (certain elements modified and added to reflect the specific PRISMA-ScR guideline, as outlined in PRISMA-P checklist) checklist is available via the Open Science Framework.
https://doi.org/10.17605/OSF.IO/ZRJT5 under CC-By Attribution 4.0 International license.20
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?
Partly
Are the datasets clearly presented in a useable and accessible format?
Not applicable
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: Clinical and public health informatics, health data analytics, early disease detection and screening, epidemiology, and evidence synthesis. I am able to assess the health-informatics relevance, study design, data methods, ethical use of health data, and public-health implications of this protocol.
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?
Partly
Are the datasets clearly presented in a useable and accessible format?
Not applicable
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: cancer early detection, machine learning, multiple omics and mass spec
Alongside their report, reviewers assign a status to the article:
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Provide sufficient details of any financial or non-financial competing interests to enable users to assess whether your comments might lead a reasonable person to question your impartiality. Consider the following examples, but note that this is not an exhaustive list:
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