The Natural History of Nonalcoholic Fatty Liver Disease: A Population-Based Cohort Study

Background & Aims: The natural history of nonalcoholic fatty liver disease (NAFLD) in the community remains unknown. We sought to determine survival and liver-related morbidity among community-based NAFLD patients. Methods: Four hundred twenty patients diagnosed with NAFLD in Olmsted County, Minnesota, between 1980 and 2000 were identified using the resources of the Rochester Epidemiology Project. Medical records were reviewed to confirm diagnosis and determine outcomes up to 2003. Overall survival was compared with the general Minnesota population of the same age and sex. Results: Mean (SD) age at diagnosis was 49 (15) years; 231 (49%) were male. Mean follow-up was 7.6 (4.0) years (range, 0.1-23.5) culminating in 3192 person-years follow-up. Overall, 53 of 420 (12.6%) patients died. Survival was lower than the expected survival for the general population (standardized mortality ratio, 1.34; 95% CI, 1.003-1.76; P = .03). Higher mortality was associated with age (hazard ratio per decade, 2.2; 95% CI, 1.7-2.7), impaired fasting glucose (hazard ratio, 2.6; 95% CI, 1.3-5.2), and cirrhosis (hazard ratio, 3.1, 95% CI, 1.2-7.8). Liver disease was the third leading cause of death (as compared with the thirteenth leading cause of death in the general Minnesota population), occurring in 7 (1.7%) subjects. Twenty-one (5%) patients were diagnosed with cirrhosis, and 13 (3.1%) developed liver-related complications, including 1 requiring transplantation and 2 developing hepatocellular carcinoma. Conclusions: Mortality among community-diagnosed NAFLD patients is higher than the general population and is associated with older age, impaired fasting glucose, and cirrhosis. Liver-related death is a leading cause of mortality, although the absolute risk is low.