Transportation barriers to healthcare access: a scoping review of measurement approaches and associated health outcomes

Background Transportation, along with cost, is a leading healthcare access barrier; however, there is no standardized measure to assess transportation barriers. Objectives To assess how transportation barriers to healthcare access and utilization are measured in U.S. studies, and to describe the types of health outcomes examined in these studies. The review focuses on constructs and operational definitions. Methods Using online databases (PubMed, Embase, CINAHL, EBSCOhost), we searched for articles published in English from 1 January 1991–24 May 2022 with a focus on articles assessing transportation as a means of accessing healthcare services or as a barrier to access/utilization of healthcare for a specified health outcome, screened by title and abstract before doing full text review and data extraction. Results Of 2,527 articles identified, 186 articles met our inclusion criteria and are descriptively summarized. Geographic specificity varied from point location to county. The most common transportation measures were estimated travel distance (n = 94) and time (n = 63), assessed as straight-lines (n = 47). Continuous results were categorized for analysis in 21 studies. Eight studies assessed supply–demand density using a floating catchment area. Health measures could be generally categorized as service access (n = 80; e.g., opioid treatment, cancer screening), healthcare utilization (n = 62; e.g., missed appointments, hospital readmissions), and disease-specific outcomes (n = 74; e.g., diagnosis, organ transplant, mortality). Conclusion We highlight the need for standardized measures and reporting to address transportation barriers across rural and urban settings, aiming to improve healthcare access and health equity. Included studies highlight the complex interactions between healthcare dynamics and transportation barriers.