NASH/Liver Fibrosis Prevalence and Incidence of Nonliver Comorbidities among People with NAFLD and Incidence of NAFLD by Metabolic Comorbidities: Lessons from South Korea

Abstract

Background: NAFLD incidence, NASH prevalence, NAFLD fibrosis prevalence, incidence of metabolic comorbidities, and mortality data in the NAFLD population remain limited. Aims: We used a meta-analytic approach to “stage” NAFLD among the Korean population. Methods: We searched PubMed, Embase, Cochrane Library, and KoreaMed from inception until June 29, 2019, and calculated pooled estimates via the random-effects model. Results: We screened 1,485 studies and analyzed 191 eligible studies: 179 (3,556,579 participants) for NAFLD prevalence and outcome analysis and 32 (1,089,785 participants) for NAFLD incidence analysis. NAFLD prevalence was 31.46% overall and 50–60% in those with metabolic risks. The incidence (per 1,000 person-years) of NAFLD was 42.8 overall and 70–77% in those with metabolic risk. The incidence (per 1,000 person-years) of new-onset T2DM, hypertension, cardiovascular disease, and chronic kidney disease was found to be 16.9, 47.9, 100.6, and 13.9, respectively. From biopsy data, 30.21% of the NAFLD population had moderate-to-severe steatosis (9 studies, 2,461 participants) and 52.27% had NASH (7 studies, 1,168 participants) and 85.41% had fibrosis <stage 2 (8 studies, 1,995 participants). All-cause mortality was 2.6 (1.3 if without malignancy) per 1,000 person-years. Conclusions: The overall prevalence of NAFLD was 31.46% with an incidence rate of 42.8 per 1,000 person-years. NASH prevalence was 52% but <15% had significant fibrosis. The prevalence and incidence of nonliver comorbidities was high especially for cardiovascular disease incidence. The burden of NAFLD is high in Korea. Health policy efforts need to be directed towards reversing the course of NAFLD disease.