Comparison all-cause mortality between individuals with COVID-19 and propensity-score-matched individuals without COVID-19 in South Korea

Oh, Tak Kyu; Song, In-Ae; Song, Kyoung-Ho; Jeon, Young-Tae

BACKGROUND: We compared all-cause mortality between individuals in South Korea with and without coronavirus disease (COVID-19), using propensity score (PS)-matching. METHODS: This population-based cohort study used data from the National Health Insurance Service COVID-19 cohort database. In the database, we included individuals (COVID-19 patients, control population, and test-negative individuals) aged 20 years or older, regardless of hospitalization. The primary endpoint was all-cause mortality between January 1, 2020 and August 27, 2020. RESULTS: A total of 328,374 adults were included in the study: 7,713 and 320,660 in the COVID-19 group and the control group, respectively. After PS-matching, a total of 15,426 individuals (7,713 per group) were included in the analysis. All-cause mortality 3.2% (248/7,713) and 1.6% (126/7,713) in the COVID-19 group and the control group, respectively. In Cox regression analysis after PS-matching, the risk of death in the COVID-19 group was twice as high (hazard ratio: 2.00; 95% confidence interval: 1.61 to 2.48; P<0.001) than that in the control group. Among patients aged ≥60 years, the COVID-19 group had a 2.32-fold higher all-cause mortality compared with the control group, while statistically statistical differences were not observed in the age groups 20–39 years (P=0.339) and 40–59 years (P=0.562). CONCLUSIONS: In South Korea, all-cause mortality was twice as high among individuals with COVID-19 than among those with similar underlying risks, primarily because of the elevated COVID-19-associated mortality in those aged ≥60 years. Our results highlight the need for prevention of COVID-19 with respect to mortality as a public health outcome.