Age, period, and cohort effects on infectious disease mortality in Korea, 1983-2017

Abstract

Abstract Background Infectious diseases are a leading cause of death worldwide, and constitute a significant burden of disease, even in developed countries including Korea. Although different ages, periods, and cohorts may affect mortality, few studies analyzed the epidemiologic pattern of infectious disease mortality considering these effects. This study aimed to estimate the age-period-cohort effects on infectious disease mortality in Korea. Methods The national death certificate and census mid-year population estimates data from 1983 to 2017 were categorized into 5-year age groups and 5-year periods. Infant deaths were excluded due to incomplete data. Intrinsic estimator regression models were fitted to estimate age-period-cohort effects on infectious disease mortality. Results A J-shaped age effect declined from age 1-4 years (intrinsic estimator coefficient [IEC] 0.68; 95% confidence interval [CI] 0.52, 0.85), the lowest at age 20-24 years (IEC -1.68; 95% CI -1.85, -1.51), and then increased with age. The declining trend of period effects was slowed down in 1998-2002 (after the 1997-1998 Asian economic crisis), and turned to an upward trend from 2008-2012 (after the 2008-2009 global financial crisis). The cohort effect increased from the earliest cohort born before 1905 (IEC -1.17, 95% CI -1.35, -0.98), peaked in the 1941-1945 cohort (IEC 1.20, 95% CI 1.10, 1.29), then plateaued out (IEC ranged from 0.93 to 1.10), and has continued to decline since the 1966-1970 cohort in which rapid economic growth began. Conclusions There were clear age, period, and cohort effects on infectious disease mortality in Korea. Through the period and cohort effects, the economic downturn and upturn might have increased or reduced infectious disease mortality, respectively. Recent upward trend in infectious disease mortality after the 2008-2009 financial crisis suggests a need to strengthen prevention and control of infectious diseases. Key messages It is important to consider age-period-cohort effects in identifying the epidemiologic pattern of infectious disease mortality trend and finding its underlying drivers. Economic cycle might have influenced infectious disease mortality through period and cohort effects.