# Introduction

Overtime is defined as “any hours worked in excess of the standard hours of work’’ (Government of Canada, 2024). Worldwide, working overtime is a serious issue (Bae & Fabry, 2014). For example, in 2022, 40% of Canadian nurses reported working overtime at least once a week (Canadian Federation of Nurses Unions, 2022). In the United States, 42% of nurses reported working overtime (Stokowski et al., 2018), whereas more than 22% of French nurses reported working overtime multiple times per week (Dickason & Dumas, 2021).

Studies have examined the impact of working overtime on both nurse and patient outcomes with conflicting results. For example, some studies suggested that working overtime is associated with adverse nurse outcomes (e.g., job dissatisfaction, occupational injuries, and fatigue) (Bae & Fabry, 2014; Carrière et al., 2020; Härmä et al., 2020), whereas other studies found no significant associations (Bannai & Tamakoshi, 2014; Watanabe, Imamura, & Kawakami, 2016). Interestingly, some studies reported the benefits of working overtime for nurses (e.g., improved work engagement and motivation, and increased income levels) (Watanabe & Yamauchi, 2018; 2019). Similar patterns have also been reported for the studies examining the associations between overtime and patient outcomes. For instance, according to some studies, working overtime may increase medication errors and infection rates (Bae & Fabry; Caruso et al., 2019; Geiger-Brown et al., 2011; Trinkoff et al., 2011), while other studies revealed beneficial outcomes of working overtime for patients (e.g., lower mortality and infection rates) (Bae & Fabry; Berney & Needleman, 2006; Stone et al., 2007).

Nurses may provide various types of overtime (e.g., mandatory, voluntary, paid, unpaid, on call hours). From this perspective, some authors postulate that the conflicting findings presented in the literature could be explained by the type of overtime performed by nurses (Watanabe & Yamauchi, 2016; Watanabe & Yamauchi, 2018; 2019). For instance, working voluntary overtime (i.e., an independent decision made by the nurse) could likely be associated with more positive nurse outcomes (e.g., increased work engagement and motivation) (Watanabe & Yamauchi, 2016; Watanabe & Yamauchi, 2018; 2019), whereas working mandatory overtime (i.e., a decision imposed on a nurse by managers) could correlate with adverse nurse outcomes (e.g., higher job dissatisfaction or increased turnover) (Medvec et al., 2023). A preliminary search of the literature was performed to identify any systematic reviews on the topic. Given the absence of recent systematic reviews since the publication of Bae and Fabry (2014), the existing evidence remains fragmented across the literature. A comprehensive synthesis is therefore needed to consolidate current knowledge, identify consistent patterns, and guide future research and practice. This systematic review aims to address this gap by providing an updated and structured overview of the available evidence.

## Objectives

The objectives of this systematic review are to: 1) summarize existing evidence on the associations between overtime work and nurse and patient outcomes; 2) identify knowledge gaps to inform future research, clinical practice, and policy development.
# Method

## Protocol Design and
				Registration

The proposed systematic review will be conducted in accordance with the Joanna Briggs Institute (JBI) methodology for systematic reviews of etiology and risk (Moola et al., 2020). Then, the findings will be reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines (Page et al., 2021). The review protocol was registered in the international prospective register of systematic reviews (PROSPERO, Registration ID: CRD42024529966).

## Search Strategy and Inclusion
				Criteria

Two nurse researchers will independently search six electronic databases to identify studies examining the association between nurse overtime work and nurse and patient outcomes: 1) MEDLINE, 2) CINAHL, 3) PscyINFO, 4) Scopus, 5) Campbell and 6) Cochrane Library. All literature searches will be performed with the assistance of a specialized health sciences librarian. Our search strategy will proceed in three successive steps.

First, several queries of the selected electronic databases will be performed by combining our selected keywords along with relevant MeSh terms (Table 1, see Appendix). Second, the same nurse researchers will independently read the titles and abstracts of the retrieved articles (and, as needed, the full manuscript) to determine whether they should be included in this review. Studies will be included if they: 1) were published between April 2013 (the latest date covered by the systematic review of Bae & Fabry, 2014) and May 2025 in a peer-reviewed journal; 2) were based on a quantitative research design; 3) examined the association between at least one independent variable and at least one dependent variable of interest (Table 2, see Appendix); and 4) were conducted in any clinical setting. No linguistic restrictions will be applied. Any retrieved manuscript written in a foreign language will be translated into English using an artificial intelligence translation tool (ChatGPT) (Li & Tian, 2024).

Final decisions about whether to include a given study or not will be made through consensus among research team members. Third, the reference lists of the included studies will be manually searched for any additional eligible studies. In addition, we will search the selected electronic databases to identify any subsequent or prior studies published by the authors of the retrieved articles that could also meet our inclusion criteria (Table 3, see Appendix).

## Study Selection

Results of database searches will be compiled and uploaded into Endnote (The EndNote Team, 2013). All identified citations will be imported into the Covidence systematic review software (Veritas Health Innovation, 2023) and duplicates removed. Then, titles and abstracts will be assessed against the eligibility criteria of the review by two independent reviewers. Relevant texts will be retrieved in full and assessed by the same reviewers. The full-text studies that do not meet our eligibility criteria will be excluded from this review. The reasons for exclusion will be presented in the systematic review. Disagreements between the reviewers will be resolved through discussion. Findings will be presented in full in the systematic review and illustrated in a PRISMA flow diagram (Page et al., 2021).

## Data Extraction

The extraction will be done in duplicate by the two independent reviewers (the same who will perform the database searches and study selection). These reviewers will extract all relevant data from papers included in this systematic review. Based on the data extraction tool developed by the JBI (Moola et al., 2020), an Excel extraction grid will be developed for the purpose of this systematic review. All extracted data will be compiled in the grid. The following information will be extracted from each included study:

Disagreements will be resolved through consensus. When data are not retrievable from the selected articles, the authors will be contacted directly.

## Data Synthesis

We will first provide descriptive statistics on the characteristics of the reviewed studies (Table 4, see Appendix). The associations between overtime work and nurse and patient outcomes will be presented in tables (Table 5, Table 6, see Appendix). We will then provide a qualitative synthesis of the available evidence. We will use *p* < 0.05 as the threshold to determine the statistical significance of the findings. Since this field is marked by significant methodological heterogeneity, no meta-analysis will be attempted.

## Assessment of Methodological
				Quality

Relevant studies will be critically appraised by two independent reviewers (the same as for the previous steps) using the JBI Critical Appraisal Checklist tool (Moola et al., 2020). JBI provides a specific checklist for each type of observational study design: Cross-sectional (8 items), case-control (10 items), and cohort studies (11 items). Each item will be rated as follows: Criterion satisfied = 1, criterion not satisfied = 0, criterion partially satisfied or unclear = 0.5. For each type of observational study, scores on each item will be summed and divided by the total number of items and converted to a percentage: Low score (score = less than 60%); moderate (score = 60-80%); high (score = > 80%). Studies of low methodological quality will not be excluded from this systematic review, as identifying such studies is an important result in itself. Therefore, we plan on reporting the percentage of retrieved studies that fall within our three categories of methodological quality (low, medium, high). Then, the literature will be summarized while considering the methodological quality of the retrieved studies (e.g., stratified by quality levels), and the risk of bias.

The results of the critical appraisal will be reported in a narrative form and in a table. Disagreements between the reviewers will be resolved through discussion.

## Discussion and Research
				Spin-offs

Working overtime is a common issue worldwide. Evidence shows inconsistent results on the associations between overtime work and both nurse and patient outcomes. Some studies reported adverse outcomes of working overtime for both nurses and patients (Bae & Fabry, 2014; Härmä et al., 2020), whereas other studies suggested no significant associations (Bannai & Tamakoshi, 2014; Watanabe, Imamura, & Kawakami, 2016) or reported some benefits of overtime work for patients and nurses (Stone et al., 2007; Watanabe & Yamauchi, 2016; Watanabe & Yamauchi, 2018; 2019). The prevailing hypothesis is that these inconsistencies could be explained by the type of overtime work performed (e.g., voluntary vs. mandatory vs. on call).

The proposed systematic review aims to explore this hypothesis through a synthesis of recent evidence. We hope that our results will inform future nursing research in the field. In addition, it is expected that this review will likely result in valuable recommendations for decision-makers. Indeed, we aim to stratify existing evidence according to the type of overtime performed. We therefore hope that such summary will assist managers in improving their use of overtime in different clinical settings.

## Dissemination

Findings from this review will be disseminated through a peer-reviewed publication and conferences.

## Timeline

## Références

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