Adherence to STROBE reporting guidelines in observational drowning research: A protocol for a systematic review

TITLE PAGE Title: Adherence to STROBE reporting guidelines in observational drowning research: A protocol for a systematic review Registration: This protocol will be publicly available at ZENODO before any analyses (registration number will be added). The protocol is conducted in accordance with the Preferred Reporting of Systematic Reviews and Meta-analyses (PRISMA) guidelines for protocols,1 and the final paper will be reported in accordance with the PRISMA guidelines.2 Corresponding author: Dr. Niklas Breindahl (MD, PhD) Prehospital Center Region Zealand Ringstedgade 61, 13th Floor, 4700 Naestved Denmark Mail: [email protected] Amendments: A new version number will be uploaded if significant protocol amendments are added to the original protocol. Support: The Danish Foundation TrygFonden supported this study. TrygFonden will not be involved in any aspects of the study, including the conceptualization, design, data collection, analysis, decision to publish, or manuscript preparation. 1. INTRODUCTION 1.1.Rationale Observational studies constitute a significant portion of drowning research, providing critical insights into risk factors, prevention strategies, and outcomes. The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines offer a standardized framework to enhance the transparency, completeness, and quality of reporting in such studies.3 Despite their importance, the extent to which drowning research adheres to STROBE guidelines remains unclear. 1.2.Objective This systematic review aims to gather and synthesize existing observational drowning studies to assess the use and conformity with STROBE guidelines and does not comprise a meta-analysis. By identifying gaps and areas of inconsistency, this review can be used to inform future research practices, ultimately improving the rigor and reliability of drowning epidemiology. 1.3.Review question The primary review question is: How frequently and to what degree do observational studies in drowning research report adherence to the STROBE guidelines? 2. METHODS 2.1.Eligibility criteria This review will include any kind of observational studies reporting exclusively on drowning incidents (all age groups). We will exclude studies without data on drowning incidents and studies reporting drowning incidents in combination with other incident types (e.g., OHCA, suicide, trauma). These two conditions (study type and condition) were used to form the search strategy (see “2.3. Search strategy”). 2.2.Information sources The search will include studies in English only, published from 2001 and onwards. We included this publication year as the limitation since the drowning definition was established by the World Health Organisation in 2001.4 Literature search will be performed in the following databases: PubMed (including MEDLINE), EMBASE, and Web of Science. The data search was first conducted in August 2025 and will be updated prior to the development of the final article. 2.3.Search strategy An experienced health sciences librarian will assist and verify the search strategy in all databases. The Boolean operators “AND” or “OR” are used to combine the different search themes in varying combinations. In the following, the exact search strategy developed for each mentioned database is described. The overall search is composed of two blocks, the first related to the study type (observational), the second related to the condition (drowning). 2.4.Final search string in PubMed This search string retrieved 1,287 hits and was last updated on August 13: • (("Drowning"[MeSH Terms] OR "Near Drowning"[MeSH Terms] OR "drowning*"[Text Word]) AND ("observation*"[Text Word] OR "cohort*"[Text Word] OR "cross sectional*"[Text Word] OR "case control*"[Text Word] OR "case cohort*"[Text Word] OR "prospective*"[Text Word] OR "retrospective*"[Text Word] OR ("Observation"[MeSH Terms] OR "Observational Study"[Publication Type] OR "Cohort Studies"[MeSH Terms] OR "Cross-Sectional Studies"[MeSH Terms] OR "Case-Control Studies"[MeSH Terms] OR "Prospective Studies"[MeSH Terms] OR "Epidemiologic Studies"[MeSH Terms] OR "Retrospective Studies"[MeSH Terms] OR "case-control stud*"[Text Word] OR "retrospective stud*"[Text Word] OR "cohort stud*"[Text Word] OR "follow-up stud*"[Text Word] OR "longitudinal stud*"[Text Word] OR "prospective stud*"[Text Word] OR "retrospective stud*"[Text Word] OR "controlled before-after stud*"[Text Word] OR "crosssectional stud*"[Text Word] OR "historically controlled stud*"[Text Word] OR "interrupted time series analysis"[Text Word] OR "seroepidemiologic stud*"[Text Word] OR "epidemiologic*"[Text Word]))) AND ((english[Filter]) AND (2001:2025[pdat])) 2.5.Final search string in Web Of Science This search string retrieved 1,412 hits and was last updated on August 25: • TS=(drowning* OR “near drowning”) AND TS=(observation* OR cohort* OR “cross sectional*” OR “case control*” OR prospective* OR retrospective* OR “follow-up stud*” OR “longitudinal stud*” OR “controlled before-after stud*” OR “historically controlled stud*” OR “interrupted time series analysis” OR epidemiologic* OR seroepidemiological*) 2.6.Final search string in Embase This search string retrieved 1,853 hits and was last updated on September 9: • exp *near drowning/ or exp *drowning/ • (drowning* or "near drowning").ti. or (drowning* or "near drowning").ab. • exp *near drowning/ or exp *drowning/ • (drowning* or "near drowning").ti. or (drowning* or "near drowning").ab. • 1 or 2 • exp *observation/ • exp *cohort analysis/ • exp *cross-sectional study/ • exp *case control study/ • exp *prospective study/ • exp *retrospective study/ • exp *follow up/ • exp *longitudinal study/ • exp *time series analysis/ • exp *epidemiology/ • exp *seroepidemiology/ • 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 • (observation* or cohort* or cross sectional* or case control* or prospective* or retrospective* or follow-up stud* or longitudinal stud* or controlled before-after stud* or historically controlled stud* or interrupted time series analysis or epidemiologic* or seroepidemiologica).mp. [mp=title, abstract, heading word, drug trade name, original title, device manufacturer, drug manufacturer, device trade name, keyword heading word, floating subheading word, candidate term word] • 15 or 16 • 3 and 17 • limit 18 to yr="2001 -Current" • limit 19 to embase • (drowning* or near drowning).mp. [mp=title, abstract, heading word, drug trade name, original title, device manufacturer, drug manufacturer, device trade name, keyword heading word, floating subheading word, candidate term word] • 17 and 21 • limit 22 to (embase and yr="2001 -Current") 2.7.Study records 2.7.1. Data management The studies are uploaded to Covidence, where removal of duplicates will be performed. Covidence is a non-for-profit web-based software that facilitates primary screening and data extraction collaboration in the work-process of conducting a systematic review. Covidence assists in keeping the studies organized during and after the selection process, and the software will be used for both importing, title and abstract screening, full text screening, and data extraction. A flowchart of the process will be created with Covidence and included in the manuscript as Figure 1. 2.7.2. Selection process The study selection is performed in two phases. According to the eligibility criteria, seven independent researchers (NB, KB, SK, JB, AR, ESB, and LMWM) will initially screen the identified studies for eligibility based on titles and abstracts. Two independent researchers will screen each study. Studies that appear to meet the inclusion criteria, or studies with uncertain eligibility, will be included for full-text screening. In the second phase of the selection process, the full-text screening phase, the same four researchers independently read through all included studies to fully verify the inclusion and exclusion criteria mentioned above. Reasons for exclusion of any studies during full-text reading will be explained. Discrepancies in any part of the selection process will be resolved by a senior researcher (TPM). The researchers are not blinded to journal titles, study authors or institutions. 2.7.3. Data collection process Before initiation of the data collection process, the research group will agree upon a standard data extraction form. The same seven researchers will then independently extract data from included studies into the specific data extraction forms in Covidence or Excel. Discrepancies in the data collection process will be resolved by an independent senior researcher (TPM). In case of missing data, incomplete data, or other inconsistencies, study authors will be contacted for further details (a maximum of one e-mail attempt). Data collected will be used for descriptive purposes only, as no meta-analysis is planned. Therefore, study quality will not be assessed. This means that no data collected will be recalculated or transformed for statistical purposes. 2.8.Data items After full-text screening and study selection, the same seven researchers will extract the following data from included studies: • Publication year • Study ID • Title • Corresponding author contact details • Country in which the study conducted • Data type o Nationwide (a single, entire nation) o Multinational (multiple, entire nations) o Single-center (e.g., one hospital) o Multi-center (e.g., multiple hospitals) o Other • Data source(s) o Please select multiple options, if relevant o Cardiac arrest registry o Surf lifeguard reports o Police reports o Media monitoring o Causes of death registry o Autopsy / coroner's report o Search and rescue reports o In-hospital health records o Pre-hospital (EMS) health records o Other • Study design o Cohort study (Cohort studies follow groups based on exposure status over time to see if an outcome develops) o Cross-sectional study (Cross-sectional studies examine exposure and outcome at a single time point to assess prevalence) o Case-control study (Case-control studies start with people who have an outcome/cases and those who don't/controls to determine past exposures) o Other • Population • Sample size • Age group o ≥18 years o <18 years o Both adults and children o Other • Reporting guidelines • STROBE guidelines used explicitly in the study o Yes (for studies that explicitly state adherence to the STROBE guideline, the researchers will assess the extent to which each STROBE item is reported) o No 2.9.Outcomes The results of this systematic review will be reported as: 1) In all included drowning studies, the frequency (number and percentage) of studies that report adherence to the STROBE guidelines will be described 2) In drowning studies that explicitly report adherence to the STROBE guidelines, the frequency (both number and percentage) of each individual STROBE reporting item will be described Based on these results, this study will answer the questions of how frequently and to what degree observational studies in drowning research report adherence to the STROBE guidelines and the common deficiencies in the reporting of observational studies in drowning research. The final paper will include a summary table with study characteristics (see “2.5. Data items”). The complete results will be available from the corresponding author upon request. 2.10. Risk of bias in individual studies Due to the aim of this systematic review, the results of the included studies will not be reported. Hence, study quality and the risk of bias will not be assessed in this review. 3. REFERENCES 1. Moher D, Shamseer L, Clarke M, et al. Preferred reporting items for systematic review and metaanalysis protocols (PRISMA-P) 2015 statement. Systematic Reviews. 2015;4(1):1. doi:10.1186/2046-4053-4-1 2. Moher D, Liberati A, Tetzlaff J, Altman DG, Grp P. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement (Reprinted from Annals of Internal Medicine). Physical Therapy. 2009;89(9):873-880. doi:10.1371/journal.pmed.1000097 3. von Elm E, Altman DG, Egger M, et al. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007;370(9596):1453-1457. doi:10.1016/S0140-6736(07)61602-X 4. van Beeck EF BC. A new definition of drowning: towards documentation and prevention of a global public health problem. Bull World Health Organ. 2005;83:853-856.