The rate of joint replacement in osteoarthritis depends on the patient's socioeconomic status : a cohort study of 71,380 patients

Background and purpose - Assessment of potential disparities in access to care is a vital part of achieving equity in health and healthcare. We have therefore studied the effect of socioeconomic status (SES) on the rates of knee and hip replacement due to osteoarthritis. Methods - This was a cohort study in Skåne, Sweden. We included all residents aged ≥ 35 years with consultations between 2004 and 2013 for hip or knee osteoarthritis. We retrieved individual information on income, education, and occupation and evaluated the rates of knee and hip replacement according to SES, with adjustment for age and sex. Professionals, legislators, senior officials, and managers, and individuals with the longest education, served as the reference group. Results - We followed 50,498 knee osteoarthritis patients (59% women) and 20,882 hip osteoarthritis patients (58% women). The mutually adjusted rate of knee replacement was lower in those with an elementary occupation (hazard ratio (HR) = 0.81, 95% CI: 0.72-0.92), in craft workers and those with related trades (HR = 0.88, CI: 0.79-0.98), and in skilled agricultural/fishery workers (HR = 0.83, CI: 0.72-0.96), but higher in the 2 least educated groups (HR = 1.2 in both). The rate of hip replacement was lower in those with an elementary occupation (HR = 0.77, 95% CI: 0.68-0.87), in plant and machine operators/assemblers (HR = 0.83, CI: 0.75-0.93), and service workers/shop assistants (HR = 0.88, CI: 0.80-0.96). The rate of hip replacement was higher in the highest income group (HR = 1.1, 95% CI: 1.0-1.2). Interpretation - There was a lower rate of joint replacement in osteoarthritis patients working in professions often associated with lower socioeconomic status, suggesting inequity in access to care. However, the results are not unanimous, as the rate of knee replacement was higher in the least educated groups