The association between socioeconomic status and the 90-day risk of cardiovascular events after total hip arthroplasty - registry-based study of 103,286 patients

Background and purpose - Patients receiving a total hip arthroplasty (THA) are subsequently at an increased risk of cardiovascular disease (CVD). Further, socioeconomic status (SES) has an effect on CVD. We evaluated whether low SES is associated with a higher risk of readmission due to CVD after THA within 90 days in a setting with universal tax-supported healthcare. Patients and methods - We performed a nationwide population-based cohort study using Danish health registries from 1995 to 2017. Individual-based information on SES markers (cohabitation, education, income, and liquid assets) was obtained for all participants. The outcome was any hospital-treated CVD. The data was transformed using the pseudo-observation method to enable an estimation of the adjusted risk ratios (RRs) with 95% confidence intervals (CI) for each marker using generalized linear regression. Results - Among 103,286 THA patients, 452 were hospitalized with CVD within 90 days after surgery. Low SES seemed to be associated with a small increased risk of CVD, as the RRs for any CVD were 1.1 (95% CI 0.7-1.7) for patients living alone vs. cohabiting, 1.3 (CI 0.7-2.3) for low education vs. high, 1.4 (CI 0.8-2.6) for low income vs. high, and 1.3 (CI 0.8-2.1) for low liquid assets vs. high. Conclusion - Living alone, low education, low income, and low liquid assets seem to be associated with a small increased risk of readmission due to CVD 90 days after THA. Wide confidence intervals in risk should be considered when interpreting the study results.