Identifying the research question

The first stage in Arksey and O’Malley’s framework involves the identification of the research question [17]. To be consistent with their recommendations, scoping review questions should be broad and should incorporate several key aspects. More specifically, the research question was developed based on the PCC (population, concept, context) framework for scoping reviews. For this study, the population will be humans. Much of the literature on AVCs and roadkilled animals has emphasized wildlife conservation efforts, physical human injury, and economic impact [1,5,10]. This scoping review will focus on collating literature that has examined the direct influence of AVCs and roadkilled animals on humans. Second, the concept in this study will be the physical, mental, and social well-being impacts, at the individual or community level, following interaction between humans and roadkilled animals, which may include hitting an animal with a motor vehicle, seeing or disposing of a roadkilled animal, or other possible behaviors. Finally, the context for this study includes roads, sidewalks, and other transportation infrastructure in rural, urban, and suburban communities. Therefore, this review will attempt to answer the following question: How does the interaction with AVCs and roadkilled animals influence health among humans?

Identifying relevant studies

Six databases will be used to identify potentially relevant records for inclusion. Specifically, Scopus, CABI Digital Library, Web of Science, Wildlife & Ecology Studies Worldwide, TRID, and PubMed will each be used to search for records related to the interactions between roadkilled animals and humans. The reference lists of included records will also be screened to identify records, as needed. Additionally, to remain broad and ensure the comprehensiveness of this scoping review, there will be no restrictions related to publication date or peer-review status. In other words, records—including peer-reviewed articles, chapters, grey literature, and other sources—from any time point will all be considered for inclusion. Indeed, a preliminary search determined that including records from various time periods and non-peer-reviewed records could strengthen the impact of this review.

Key terms that will be input into the six databases are based on how prior scholars and journals have described the phenomena of interest. Table 1 organizes the search terms by the core concepts of 1) AVCs and roadkilled animals and 2) human health and well-being. Boolean terms (e.g., and, or) and other appropriate syntax (e.g., asterisks, quotation marks) will be applied to the searches. The search strategy will include key terms, Boolean operators, and appropriate syntax across all fields. The search strategy is available in S2 File. The scoping review search was completed on January 6; subsequent steps, such as record screening and data extraction, have not yet begun.

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Table 1. Search terms organized by core concept.

https://doi.org/10.1371/journal.pone.0341107.t001

Study selection

Identified records will be uploaded to Covidence (https://www.covidence.org/), an online management software for reviews. Covidence, which has a free trial version, will be used as a tool to organize the records and automatically remove duplicates, but will not be used to conduct analyses or make decisions for the research team. Indeed, each of these steps can be replicated by other research teams without the use of Covidence. For example, researchers performing scoping reviews without Covidence may manually check all records to identify and remove duplicates.

Afterwards, the titles and abstracts of each included record will each be independently screened by two of three reviewers. Full-texts of records that passed the title and abstract screening but are unavailable in the universities’ library systems at the authors’ institutions will be retrieved by contacting the author(s) of the record via email. However, records will be excluded if the author(s) of the record are unresponsive to requests or if the record is otherwise inaccessible. Then, the full-texts of articles that passed the title and abstract screening will be similarly independently screened by two of three reviewers. At each stage, the three reviewers will meet to discuss and resolve any discrepancies. Specifically, the three authors will discuss all discrepancies until a unanimous decision has been reached. The study selection process will be guided by the inclusion and exclusion criteria listed below. The research team anticipates record screening to be completed in March 2026.

Charting the data

Data will be charted via a standardized extraction form, displayed in S3 File. The data from each included record will be extracted by one reviewer. Then, another reviewer will read and validate the extractions. The three reviewers will meet to discuss and resolve any discrepancies. The research team anticipates data extraction to be completed in April 2026.

Collating, summarizing, and reporting the results

As recommended by Arksey and O’Malley, extracted data will be analyzed in two ways [17]. First, data will be analyzed via a narrative approach that describes the distribution of records based on geographic location and key outcomes. Second, data will be organized into themes, and key findings will be described.

Basic content analysis will be performed to facilitate this process [18–20]. Due to the broad nature of the research aim and the dearth of research in this area, an inductive coding approach will be used. Indeed, as recommended by Pollock et al., an inductive approach to coding in scoping reviews is best when the goal of the study is to develop a broad understanding of existing research in a given area [20]. As such, a codebook will not be created in order to preserve an inductive coding approach. Using a predefined codebook could constrain analysis by requiring data to fit pre-existing codes, which could prevent the research team from capturing nuanced or unexpected data [20].

This approach will involve multiple phases of coding. First, reviewers will re-familiarize themselves with the data by reading and re-reading the extracted content. Then, data from the key findings section of the extraction form will be coded inductively and independently by two reviewers. Two reviewers will use open coding to code the extracted data. Afterward, the three reviewers will meet to discuss the codes and resolve any discrepancies. Specifically, discrepancies will be resolved through conversation until a consensus is reached. Next, the three reviewers will independently sort the codes into categories and subcategories based on their similarities and differences. Throughout this process, numerical counts of codes will be used to help determine key findings and research gaps related to the research question in this review. The reviewers will then meet again to discuss and finalize the categories and subcategories. The reviewers will return to the included records to confirm that the categories and subcategories accurately reflect the data. Revisions to the categories and subcategories will be made, if necessary. Finally, the categories and subcategories will be described textually and depicted via tables and/or figures.

Note, though, that the reporting of the results will only involve a description of the key findings and will not involve a synthesis of key findings. This decision aligns with best practices for performing a scoping review [13,20]. Relatedly, in alignment with the purposes of a scoping review, a critical appraisal of the evidence will not be conducted [13,20]. The research team anticipates results to be completed in June 2026.

Discrepancies between the protocol and final review

Any discrepancies between this protocol and the final version of the scoping review will be noted. If discrepancies occur, a rationale will be provided.