This retrospective study was conducted using data from the 2011‐2017 National Health Interview Survey (NHIS). The NHIS is administered in-person annually and is a cross-sectional survey of noninstitutionalized adults in the United States [4]. Knee arthritis was defined by answers to questions pertaining to self-reported physician-diagnosed knee arthritis as well as self-reported knee pain. Among respondents who were told “by a doctor or other health professional that [they had] some form of arthritis, rheumatoid arthritis, gout, lupus, or fibromyalgia,” knee arthritis was defined by those who indicated that they experienced “symptoms of pain, aching, or stiffness in or around a joint.” (Multimedia Appendix 1). Adults who agreed to the statement, “Have you delayed getting care for any of the following reasons…In the past 12 months…You didn’t have transportation” met the criteria for experiencing barriers to health care due to transportation delays (Multimedia Appendix 1).

Sociodemographic variables were used as covariates. Univariable and multivariable logistic regressions were conducted using R Studio (version 1.4.1106; R Foundation for Statistical Computing), α=0.05. Weighted analysis generated nationally representative results. Participants were excluded from this study if questions regarding knee arthritis or transportation delays were unanswered or if key sociodemographic factors were missing.

Per National Institute of Health (NIH) guidelines, this research does not meet the definition of human subjects research as this data is publicly available, anonymized, and not obtained for the purposes of this study; therefore, institutional review board approval was not required for this secondary analysis [5].

Black individuals were associated with increased odds of transportation delays. Studies highlight that residential segregation along racial lines impact Black individuals’ ability to access health care [6]. A retrospective 20-year period study has found that among Black individuals in the United States, a high level of residential segregation coupled with a high density of low-income residents increased the odds of urban hospital closures [7]. Thus, it is plausible that hospital closures and other such factors associated with residential segregation may place these communities further away from medical facilities, which could further exacerbate access to reliable and efficient transportation.

Our study revealed that individuals with an annual income of 100%‐200% above the federal poverty level as well as individuals<100% the federal poverty level experience increased odds of transportation delays. This may reflect difficulties with car ownership among lower-income individuals, as previous analyses have shown that among cancer patients, lacking a private vehicle decreases treatment odds [8]. Additionally, individuals with public insurance plans and individuals with no insurance were more likely to experience transportation delays in our study. This may be attributable to the increased costs of travel experienced by those with public or no insurance. In a study observing travel distance among those in need of HIV medical care, it was found that those with no insurance traveled further than those with public insurance [9]. In fact, a key policy recommendation for reducing transportation barriers in accessing healthcare includes insurance coverage that is inclusive of transportation [10].

Strengths of this study are its usage of a nationally representative sample and a large sample size. Limitations include biases with self-reported data, additional confounders not included in this model, and the cross-sectional nature of the data, which prohibits casual inferences.