Association Between Nonalcoholic Fatty Liver Disease and the Incidence of Asthma in Adults: Finding from a Nationwide Study in Korea

Asthma and nonalcoholic fatty liver disease (NAFLD) are chronic diseases and are known to be associated with metabolic abnormalities. We aimed to clarify the association between NAFLD and the incidence of asthma in a large population-based cohort. We selected 160,603 healthy individuals without comorbidities from the National Health Insurance Service-National Sample cohort during 2009–2014. . NAFLD was defined by a surrogate marker, the fatty liver index (FLI). During a median of 5.08 years’ follow-up, 16,377 subjects (10.2%) were newly diagnosed with asthma and categorized into three groups according to FLI. The cumulative incidence of asthma was higher in subjects with higher vs. lower FLIs (FLI < 30 10.1%, 30 ≤ FLI < 60 10.8%, FLI ≥ 60 10.5% ). Higher FLI associated with an increased incidence of asthma (Harzard ratios (HR)highest vs. lowest FLI, 1.25; 95% CI, 1.15-1.36). The results using another definition of NAFLD as measured by hepatic steatosis index (HIS) are similar to the primary results. This association was more pronounced in women than in men (HR 1.46; 95% CI, 1.13-1.64 vs. HR 1.07; 95% CI, 0.94-1.20). This study demonstrated that NAFLD as measured by FLI and HIS may influence the incidence rates of asthma in adults, especially in women.