OBJECTIVES: Non-alcoholic steatohepatitis (NASH) is the progressive form of non-alcoholic fatty liver disease (NAFLD) defined by a buildup of fat in the liver and signs of inflammation, liver damage and progressive fibrosis. NASH is associated with non-specific symptoms making diagnosis difficult and leading to undetected disease progression. Patients with NASH may develop cirrhosis, leading to clinical decompensation, liver cancer, and liver failure, affecting morbidity and mortality. The goal of this study was to estimate the burden of NASH in the US, which is not well understood.

METHODS: A burden of illness model was constructed to assess the degree of health foregone in the US as a direct result of NASH using available epidemiological data. The degree of health foregone is measured by a loss of expected quality-adjusted life years (QALYs) in a population susceptible to NASH compared to a population where NASH is absent. First, a Markov Model for NASH starting in the first stage of fibrosis (incident model) was constructed. Second, the model was expanded to include patients starting in the healthy stage and transitioning into the incident NASH model.

RESULTS: NASH is estimated to account for 22 million QALYs lost for males and 26 million for females across the 338 million population of the US. The proportion of the QALY burden due to morbidity is 67% in males and 65% in females. The indolent nature of NASH, particularly at the early stages, means the burden of disease falls largely on older age groups in the population where the relative share of burden due to mortality is slightly higher than in the younger age groups.

CONCLUSIONS: This analysis shows that NASH remains a substantial public health challenge in the US and is responsible for a considerable loss of life and health related quality of life due to progression of liver disease.