Abstract
OBJECTIVE: Access to specialized orthopedic care is an important determinant of the decision to undergo total knee replacement (TKR); however, most studies have mainly used distance to the nearest high-volume hospital as the primary proxy for access. We applied the two-step floating catchment area (2SFCA) method to develop a more comprehensive TKR access score that accounts for other potential factors (ie, supply of and demand for this procedure) that also affect access. METHODS: To apply the 2SFCA method, we first estimated TKR demand using the Centers for Disease Control and Prevention estimates of prevalence of osteoarthritis, which were multiplied by estimates of patients who would potentially benefit from TKR. We then estimated TKR supply using the number of TKRs performed in each hospital, extracted from the Centers for Medicare and Medicaid Services Medicare Provider Analysis and Review database. For the nationwide analysis, we estimated the access score for a radius of 55 km around each census tract in the contiguous United States. For a subset of the census tracts, we employed a more realistic but more computationally intensive 42-minute driving distance to determine the robustness of the 55-km assumption and calculated the Spearman rank correlation between the two access scores. RESULTS: Across the United States, the access score was categorized as low for 51%, medium for 24%, and high for 25% of census tracts. The Spearman correlation coefficient between these national scores and those with a 42-minute driving time was 0.75. CONCLUSION: We developed a novel TKR care access score that may enhance quality measures available to patients, providers, payers, and researchers.