Effects of individual and neighborhood socioeconomic status on the risk of all-cause mortality in chronic obstructive pulmonary disease: A nationwide population-based cohort study, 2002-2013

Background Numerous previous studies have shown that individual socioeconomic status (SES) is associated with mortality in patients with chronic obstructive pulmonary disease (COPD), but few empirical studies have evaluated the effects of individual SES and neighborhood deprivation on mortality in COPD patients. Methods We performed a prospective cohort study to examine the effect of socioeconomic disparity on all-cause mortality in newly diagnosed COPD patients in a setting with universal health care coverage. We used representative population-based nationwide cohort data from the Korean National Health Insurance claims database (2002-2013). We included patients who were at least 40 years old and newly diagnosed with COPD (N = 9275). To analyze the data, we utilized a frailty model and Cox's proportional hazard regression. Results A total of 1849 (19.9%) of the 9275 eligible participants died during the study period. Compared to high-income patients from advantaged neighborhoods, the adjusted hazard ratio (HR) for middle-income COPD patients who lived in advantaged and disadvantaged neighborhoods was 1.22 (95% CI, 1.03-1.43) and 1.36 (95% CI, 1.15-1.60), respectively. For low-income patients, the adjusted HR for patients who lived in disadvantaged neighborhoods was higher than for patients who lived in advantaged neighborhoods (HR, 1.43; 95% CI, 1.17-1.74 vs. HR, 1.36; 95% CI, 1.11-1.66). There was no difference in the adjusted HRs for high-income patients who lived in advantaged and disadvantaged neighborhoods (HR, 1.01; 95% CI, 0.84-1.22). Conclusions Socioeconomic disparity contributes to all-cause mortality in COPD patients and neighborhood deprivation exacerbates the effect of individual SES on all-cause mortality in COPD patients.