Keywords
hospital-acquired, nursing-sensitive, failure to maintain, adverse event, delirium, urinary tract infection, pneumonia, pressure ulcer
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McCauley R, Connolly A, Matthews A and Kirwan M. Reported Rates of Hospital-Acquired Adverse Events in Older Hospitalised Adults: A Scoping Review (Protocol) [version 1; peer review: awaiting peer review]. HRB Open Res 2025, 8:98 (https://doi.org/10.12688/hrbopenres.14234.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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Study Protocol
Reported Rates of Hospital-Acquired Adverse Events in Older Hospitalised Adults: A Scoping Review (Protocol)
[version 1; peer review: awaiting peer review]
PUBLISHED 03 Sep 2025
OPEN PEER REVIEW
REVIEWER STATUS
This article is included in the Ageing Populations collection.
Abstract
Corresponding author:
Rachel McCauley
Competing interests:
No competing interests were disclosed.
Grant information:
This work is supported by funding from the Health Research Board for the COST2CARE project [ILP-HSR-2022-009] and its resultant Knowledge Transfer Award [KTA-2024-001].
Copyright:
© 2025 McCauley R 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: McCauley R, Connolly A, Matthews A and Kirwan M. Reported Rates of Hospital-Acquired Adverse Events in Older Hospitalised Adults: A Scoping Review (Protocol) [version 1; peer review: awaiting peer review]. HRB Open Res 2025, 8:98 (https://doi.org/10.12688/hrbopenres.14234.1)
First published: 03 Sep 2025, 8:98 (https://doi.org/10.12688/hrbopenres.14234.1)
Latest published: 03 Sep 2025, 8:98 (https://doi.org/10.12688/hrbopenres.14234.1)
Introduction
Hospital-acquired adverse events (HAAEs) such as delirium, pressure injuries or infections are adverse events that either occurred during or were exacerbated by a patient’s stay in hospital, that are not caused by or an effect of the patient’s reason for admission (Khan et al., 2017). The occurrence of HAAEs can have serious consequences for patients, including prolonged hospital stays, decreased functional capacity, and increased risk for both disability and death during or after a hospitalisation (Avadhani et al., 2025). Patients over the age of 65 experience these events more often and more acutely than younger patients, in part due to an increase in co-morbidities within this cohort, reduced immune response and increased functional decline in comparison to younger adults (Avci et al., 2012; Tesini & Dumyati, 2023). Despite the heightened vulnerability within this cohort, a priori research predominantly records HAAEs as they arise in a general patient cohort of all ages, allowing the data for patients over 65 to be lost within the general population. Thus, estimating rates of HAAEs in older patients is difficult due to the dilution of the data of this cohort with that of other age groups.
Delirium, pneumonia, pressure injuries and urinary tract infections are of particular relevance to the over 65 patient group, with their occurrence often contributing to general functional and cognitive decline within this cohort. These events have been linked to nursing care rationing within hospitals, with patients with more advanced care needs often having elements of their care missed due to nurses’ prioritisation of the most critical tasks with limited time (Jones et al., 2015). As such, these nursing-sensitive events have come to have been grouped as ‘Failure To Maintain’ conditions, named as such due to their impact on an older person’s functioning and quality of life (Bail & Grealish, 2016).
Recording accurate rates of these events is fundamental for those who care for patients at micro, meso and macro level. Resourcing healthcare professionals sufficiently to attend to these adverse events, optimally before they occur through preventative measures, is pivotal to patient safety (Avadhani et al., 2025). Preventing and managing these events requires a multidisciplinary approach, with a variety of professionals with a range of expertise equipped with the right resources, training, and time to predict and respond to these potentially disabling injuries. Preventative measures such as early mobility protocols, risk assessment, repositioning, infection control practices, nutritional support, supervision in intubation and catheterisation, and practical resources such as mattress overlays have been found to enhance patient outcomes in the face of HAAE risk (Gray et al., 2023; Ocampo et al., 2017). Due to the considerable funding needed to provide specialist resources, in addition to training and supporting those identifying and treating these injuries, HAAEs are highly costly, with estimates that costs of providing treatment to patients who acquire injuries while hospitalised are 23 times the cost of patients without HAAEs (Kurutkan et al., 2015). It is therefore pivotal that the limited resources aimed at these events are economical and effective (Cristina et al., 2021).
Multidisciplinary healthcare professionals, health economists and policymakers within government require accurate rates of the prevalence of these events to understand where to efficiently allocate funds and resources. Capturing accurate data also contributes to a hospital’s accountability and transparency, ensuring that hospitals can understand where they are meeting or failing to meet regulatory standards, and where they stand in relation to comparable healthcare settings (Walsh et al., 2021). Furthermore, recording HAAEs decreases healthcare costs by reducing the prevalence of such events and consequently reducing the likelihood of long hospital stays, which are known to increase the likelihood of further adverse events and decreased mobility in patients (Rahmqvist et al., 2016). Overall, the systematic collection of accurate data pertaining to hospital-acquired adverse events is essential to delivering patient-centred care, reducing functional decline in patients, and ensuring allocative efficiency for funding bodies (Raoofi et al., 2023).
Older patients in the health system account for the majority of complex and extended hospitalisations due to the prevalence of comorbidities, vulnerability to adverse events and infection and a decreased immune response within this cohort. The world’s population is aging, with the number of people over 65 in Ireland increasing by 40% in the last fifteen years (Central Statistics Office, 2024). In addition, due to increasing life expectancy in Ireland and most other high-income countries, patients are utilising hospital care and treatment for longer than ever before (Wren et al., 2017). Therefore, in Ireland, these most high-cost patients are at most risk of hospital-acquired adverse events and in need of an increased level of care for an average of twenty years (Eurostat, 2025). Mapping the prevalence of the specific hospital-acquired adverse events (delirium, pneumonia, pressure injuries and urinary tract infections) in this age group will contribute to a body of research that will assist policymakers in meeting future demand and improving patient safety, both locally and nationally. Recent research has indicated the importance of accurately captured administrative data in the pursuit of optimal patient safety and healthcare quality (Connolly et al., 2024). A focused synthesis of prevalence data that is specific to those over 65, the age group in receipt of the most medical intervention, will provide more accurate and contextualised information with which to develop interventions for this rapidly increasing group.
While a significant body of research has been developed in all four of the included injuries of interest, no a priori scoping review has thus far focused on these areas of interest. A preliminary search of MEDLINE, the Cochrane Database of Systematic Reviews and JBI Evidence Synthesis was conducted and no current or underway systematic reviews or scoping reviews on the topic were identified. This scoping review aims to map the existing evidence base, identify gaps in knowledge, and highlight areas for future research related to the burden of HAAEs on patients, healthcare professionals and health systems at large.
Review question
As recommended by the Joanna Briggs Institute (JBI), the JBI Population, Concept and Context framework was employed to formulate the research questions central to this review (Peters et al., 2020). Outcomes of this framework can be found in Table 1.
Table 1. JBI Population, Concept and Context Framework Output.
| Population | Concept | Context |
|---|---|---|
| Patients aged 65 years or older | Prevalence of hospital acquired delirium pneumonia, pressure injuries and urinary tract infections | Acute general hospital |
The review questions that arose from this framework were therefore as follows:
1. What are the reported rates of hospitalised patients aged 65 years and older who experience hospital-acquired adverse events, namely delirium, pneumonia, pressure injuries or urinary tract infections, in hospital settings?
2. How are the four included HAAEs defined, measured and reported across different studies, as well as the potential influence the setting of each study and their demographic, contextual factors?
Inclusion criteria
Participants
Studies must include patients that are over 65 years of age and hospitalised in acute hospitals to be eligible for inclusion in the present study. This group has been selected as patients over 65 years of age are disproportionately affected by the hospital-acquired adverse events investigated in the present review.
Concept
The primary concept underpinning this scoping review is the identification and quantification of hospital-acquired adverse events (HAAEs) affecting adults aged 65 or older during their hospitalisation. HAAEs are defined as unintended injuries or complications that occur during the course of hospitalisation and are not caused by and often unrelated to the condition for which the patient was admitted (Khan et al., 2017).
Patients over 65 are more likely to experience HAAEs due to higher prevalence of multimorbidity, functional decline, and longer stays on hospital in comparison to younger adults (Avci et al., 2012; Tesini & Dumyati, 2023). Having accurate information on the prevalence and types of HAAEs most affecting this population is essential to providing optimal patient safety, effective and fit-for-purpose training, clinical decision-making and efficient resource allocation (Cristina et al., 2021). The present review will focus on studies that report on the rates or frequencies of patients with HAAEs specifically in hospitalized patients aged 65 years and older within the acute general hospital settings (e.g. medical, surgical, critical care, care of the older person).
Context
Studies will be included if they are carried out within a hospital setting in a middle- or high-income country. This is pertinent to this study as this piece of work will inform further work within this project, requiring the context of studies found in this review to be similar to the context of the present project (i.e. hospital setting in a high-income country) in order for the data found to be comparable. The present review will define high or high-middle income countries as per the most recent World Bank definition at time of publication (World Bank, 2025).
Types of sources
This scoping review will consider all study designs. This inlcudes experimental and quasi-experimental study designs including randomized controlled trials, non-randomized controlled trials, before and after studies and interrupted time-series studies. In addition, analytical observational studies including prospective and retrospective cohort studies, case-control studies and analytical cross-sectional studies will be considered for inclusion. This review will also consider descriptive observational study designs including case series, individual case reports and descriptive cross-sectional studies for inclusion.
Methods
The proposed scoping review will be conducted in accordance with the JBI methodology for scoping reviews and the employment of the corresponding data extraction tool (Peters et al., 2020), in addition to the steps laid out in the PRISMA checklist for scoping reviews (PRISMA-ScR) (Tricco et al., 2018).
Search strategy
The search strategy will aim to locate published studies pertaining to the rates of the four relevant hospital-acquired adverse events. A three-step search strategy will be utilized in this review. First an initial limited search of MEDLINE (PubMed) was undertaken to identify articles on the topic. The text words contained in the titles and abstracts of relevant articles, and the index terms used to describe the articles were used to develop a full search strategy, which would be sufficiently succinct and exhaustive to be applied to the included databases. Databases included in the present review will be Medline, CINAHL, EMBASE, and the Cochrane Library. The search strategy, including all identified keywords and index terms, will be adapted for each included database and/or information source. The reference list of all included sources of evidence will be screened for additional studies. The search strategy for the present study can be found on the Open Science Framework (OSF; https://doi.org/10.17605/OSF.IO/6WMCH)
Studies will be eligible for inclusion if they qualify as original peer-reviewed studies published in full and in English. The scoping review will include studies from January 1st, 2000 to 30th June 2025. The origins of recording and tracking hospital-acquired urinary tract infections (Sanford, 1964) and pressure injuries (Loehne, 1967) appeared as early as the 1960s, with pneumonia coming to prominence in the 1980s (McEachern & Campbell, 1998), and hospital-acquired delirium appearing in peer-reviewed literature in the later 1990s (Inouye, 1998; Inouye et al., 1999). However, it could be argued that substantial understanding of acquired injury and adverse events in hospital was patient-safety movement Due to this variation, and in order to ensure modernity of literature, a date of 1st January 2000 was selected as the earliest date of publication eligible for inclusion. Grey literature will not be included in the review.
Study/Source of evidence selection
Following the search, all identified citations will be collated and uploaded into Covidence and duplicates removed. Following a pilot test, titles and abstracts will then be screened by two independent reviewers for assessment against the inclusion criteria for the review. Potentially relevant sources will be retrieved in full, and their citation details imported into Covidence for full text screening. The full text of selected citations will be assessed in detail against the inclusion criteria by two or more independent reviewers. Reasons for exclusion of sources of evidence at full text that do not meet the inclusion criteria will be recorded and reported in the scoping review. If consensus does not occur between reviewers on any data source, reviewers will discuss these data sources until consensus is reached. If no consensus is reached, an impartial reviewer will assist in drawing a conclusion. The process of data inclusion and exclusion will be outlined and described in the scoping review with further clarification made with the employment of a PRISMA flow chart.
Data extraction
Data will be extracted from papers included in the scoping review by two independent reviewers using a data extraction tool, Covidence, under the guidance of the recommendations of the Joanna Briggs Institute for the extraction of data within scoping reviews (Pollock et al., 2023). The data will be extracted in accordance with the inclusion and exclusion criteria as laid out in the JBI data extraction form, developed by Peters et al. (2020) which can be found under the study materials on the Open Science Framework (OSF; https://doi.org/10.17605/OSF.IO/6WMCH).
This data extraction tool will be subject to revisions as required throughout the data extraction process from each of the included databases (Peters et al., 2020). These amendments will be described in the scoping review. If consensus does not occur between reviewers on any data source, reviewers will discuss these data sources until consensus is reached. If no consensus is reached, an impartial reviewer will assist in drawing a conclusion.
Data analysis and presentation
Data will be mapped into four tables, with each chart describing the evidence found for pressure injuries, pneumonia, delirium and urinary tract infections, respectively. The evidence will provide descriptive contextual information which will delineate rates found in the specific disciplines within the hospital setting that arise in the data. Each eligible study included in the review will be described using the following headings: author(s), year published, country of origin, study setting, study population, and the rates of the relevant HAAE found within the study. A narrative description will accompany the tables to provide richer explanation of the results and to further explain how the included articles relate to and satisfy the research objectives.
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McCauley R, Connolly A, Matthews A and Kirwan M. Reported Rates of Hospital-Acquired Adverse Events in Older Hospitalised Adults: A Scoping Review (Protocol) [version 1; peer review: awaiting peer review]. HRB Open Res 2025, 8:98 (https://doi.org/10.12688/hrbopenres.14234.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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