Household Disposable Income and Long-Term Survival After Cardiac Surgery : A Swedish Nationwide Cohort Study in 100,534 Patients

BackgroundLower socioeconomic groups face higher mortality risk, possibly due to a higher burden of cardiovascular risk factors. The independent association between income and survival following cardiac surgery is not known.ObjectivesThis study sought to investigate the association between household disposable income and long-term mortality after cardiac surgery.MethodsIn a Swedish nationwide population-based analysis, we included all patients who underwent cardiac surgery between 1999 and 2012 using a large national registry. Information regarding income, education, marital status, medical history, and cardiovascular risk factors was obtained from data managed by the National Board of Health and Welfare and Statistics Sweden. The adjusted risk for all-cause mortality was estimated using Cox regression by quintiles of household disposable income.ResultsWe included 100,534 patients and, during a mean follow-up of 7.3 years, 29,176 (29%) patients died. There was a stepwise inverse association between household disposable income and all-cause mortality: the adjusted hazard ratio was 0.93 (95% confidence interval [CI]: 0.89 to 0.96), 0.87 (95% CI: 0.84 to 0.91), 0.78 (95% CI: 0.75 to 0.82), and 0.71 (95% CI: 0.67 to 0.75), for the second, third, fourth, and fifth income quintiles, respectively, compared to the first (and lowest) income quintile. The inverse association between income and mortality was consistent through the study period and in selected subgroups, although it was slightly attenuated in older patients.ConclusionsWe found a strong inverse association between income and mortality following cardiac surgery in Sweden that was independent of other socioeconomic status variables, comorbidities, and cardiovascular risk profile. Ways to better implement secondary prevention measures should be explored in low-income patient groups. (HeAlth-data Register sTudies of Risk and Outcomes in Cardiac Surgery [HARTROCS]; NCT02276950)