Disparities in major joint replacement surgery among adults with Medicare supplement insurance.

The objective of this study was to determine if disparities in hip and knee replacement surgery exist among osteoarthritis patients with AARP-branded Medicare supplement plan (ie, Medigap) coverage provided by UnitedHealthcare. Patients were selected into the study if they had 1 or more medical claims with a diagnosis of osteoarthritis from July 1, 2006 to June 30, 2007. Logistic regression analyses tested for age-, sex-, race-, or income-related differences in the likelihood of receiving a hip or knee replacement surgery. The regression models controlled for socioeconomics, health status, type of supplement plan, and residential location. Of the 2.2 million Medigap insureds eligible for this study, 529,652 (24%) had osteoarthritis. Of these, 32,527 (6.1%) received a hip or knee replacement. Males were 6% (P <  0.001) more likely than females to have a replacement surgery. Patients living in minority or lower income neighborhoods were less likely to receive a hip or knee replacement. Supplement plan type was not a strong predictor of the likelihood of hip or knee replacement. Disparities were much greater by comorbid condition and residential location. Disparities in hip and knee replacement surgery existed by age, sex, race, and income levels. Larger disparities were found by residential location and comorbid condition. Interventions are being considered to address these disparities.