Body mass index and risk of non-alcoholic fatty liver disease: two electronic health record prospective studies

Abstract

Context: The relationship between rising body mass index (BMI) and prospective risk of non-alcoholic fatty liver disease (NAFLD) / non-alcoholic steatohepatitis (NASH) is virtually absent. Objective: Determine the extent of the association between BMI and risk of future NAFLD diagnosis, stratifying by sex and diabetes. Design: Two prospective studies using Humedica and THIN with 1.54 and 4.96 years of follow-up respectively. Setting: Electronic health record databases Participants: Patients with had a recorded BMI measurement between 15–60kg/m2, and smoking status, and one year of active status prior to baseline BMI. Patients with a diagnosis or history of chronic diseases were excluded. Interventions: None Main Outcome Measure: Recorded diagnosis of NAFLD/NASH during follow-up (Humedica ICD-9 code 571.8, and read codes for NAFLD and NASH in THIN). Results: Hazard ratios (HR) were calculated across BMI categories using BMI of 20–22.5kg/m2 as the reference category, adjusting for age, sex and smoking status. Risk of recorded NAFLD/NASH increased linearly with BMI and was approximately 5-fold higher in Humedica (HR=4.78, 95% CI 4.17–5.47) and 9-fold higher in THIN (HR=8.93, 7.11–11.23) at a BMI of 30–32.5 kg/m2 rising to around 10-fold higher in Humedica (HR=9.80, 8.49–11.32) and 14-fold higher in THIN (HR=14.32, 11.04–18.57) in the 37.5–40 kg/m2 BMI category. Risk of NAFLD/NASH was approximately 50% higher in men, and approximately double in those with diabetes. Conclusions: These data quantify the consistent and strong relationships between BMI and prospectively recorded diagnoses of NAFLD/NASH and emphasize the importance of weight reduction strategies for prevention and management of NAFLD