Association of Statin Adherence With the Development of Nonalcoholic Fatty Liver Disease: A Nested Case-Control Study Using a Japanese Claims Database

Abstract

Background: Statins are expected to have beneficial effects on nonalcoholic fatty liver disease (NAFLD); however, evidence remains insufficient. Objective: In this study, we aim to investigate the association between statin adherence and NAFLD development. Methods: We conducted a nested case-control study of statin users using the Japan Medical Data Center administrative claims database (January 2005 to January 2020). Individuals who developed NAFLD were designated as cases. For each case, we randomly selected a maximum of 10 controls using risk set sampling. Good adherence was defined as the proportion of days covered (PDC) of ≥0.80. Higher intensity was defined as the median or higher of a cumulative defined daily dose (cDDD) per day covered by statin prescription. Conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Results: In this study, 253 383 patients with the first statin prescription were identified. Of them, 7080 were selected and matched to 70 734 controls. The medians of PDC and intensity were 0.88 (interquartile range [IQR], 0.61-0.96) and 0.32 (IQR, 0.25-0.50) cDDD/day, respectively. Good adherence was significantly associated with a reduced risk of NAFLD development (adjusted OR, 0.82; 95% CI, 0.78-0.86). Higher intensity was not significantly associated with a reduced risk of NAFLD development (adjusted OR, 1.02; 95% CI, 0.97-1.08). Conclusion and Relevance: Good adherence to statins is associated with a reduced risk of NAFLD development, regardless of the statin intensity. Appropriate statin therapy could reduce the risk of NAFLD development.