Jason C Simeone,1 Jay P Bae,2 Byron J Hoogwerf,3 Qian Li,1 Axel Haupt,3 Ayad K Ali,4 Marilyn K Boardman,3 Beth L Nordstrom1 1Real-world Evidence, Evidera, Waltham, MA, USA; 2Global Patient Outcomes and Real World Evidence, Eli Lilly and Company, Indianapolis, IN, USA; 3Lily Diabetes, Eli Lilly and Company, Indianapolis, IN, USA; 4Global Patient Safety, Eli Lilly and Company, Indianapolis, IN, USA Purpose: To identify the characteristics and initial disease severity of patients with nonalcoholic fatty liver disease (NAFLD) and assess incidence and risk factors for disease progression in a retrospective study.Methods: Patients ≥18 years of age without alcoholism or other liver diseases (eg, hepatitis B/C) were selected from Geisinger Health System electronic medical record data from 2004 to 2015. Initial disease stage was stratified into uncomplicated NAFLD, advanced fibrosis, cirrhosis, hepatocellular carcinoma (HCC), and liver transplant using clinical biomarkers, diagnosis, and procedure codes. Disease progression was defined as stage progression or death and analyzed via Kaplan–Meier plots and multistate models.Results: In the NAFLD cohort (N=18,754), 61.5% were women, 39.0% had type 2 diabetes mellitus (T2DM), and the mean body mass index was 38.2±10.2 kg/m2. At index, 69.9% had uncomplicated NAFLD, 11.7% had advanced fibrosis, and 17.8% had cirrhosis. Of 18,718 patients assessed for progression, 17.3% progressed (11.0% had stage progression, 6.3% died without evidence of stage progression) during follow-up (median=842 days). Among subgroups, 12.3% of those without diabetes mellitus progressed vs 24.7% of those with T2DM. One-year mortality increased from 0.5% in uncomplicated NAFLD to 22.7% in HCC. After liver transplant, mortality decreased to 5.6% per year.Conclusions: In 2.3 years of follow-up, approximately 17% of patients progressed or died without evidence of stage progression. T2DM was associated with approximately twice the risk of disease progression, and mortality risk increased with disease stage. Early diagnosis and monitoring of disease progression, especially in patients with T2DM, is warranted. Keywords: NAFLD, clinical course, disease progression, multistate model, retrospective study, type 2 diabetes