Nonalcoholic fatty liver disease (NAFLD) afflicts one in every three adult Americans and it is the most common cause of elevated serum aminotransferases in the United States.[1-4] NAFLD is seen in individuals who consume little or no alcohol. It can range from the presence of steatosis alone, which is expected to have a nonprogressive course, to nonalcoholic steatohepatitis (NASH), the progressive form of NAFLD that can lead to advanced fibrosis, cirrhosis, and hepatocellular carcinoma in a subset of patients.[3, 5-8] Liver biopsy in NASH is typically characterized by steatosis, lobular inflammation, and ballooning degeneration with or without perisinusoidal fibrosis.[9, 10]
Children and adolescents with NAFLD may have a different pattern of liver injury than adult patients with NAFLD.[11-13] This suggests that as an individual grows or ages NAFLD phenotypes may vary. However, there are limited data examining whether we see a different pattern of liver histology in elderly patients with NAFLD. Several groups have now shown that older age is a risk factor for NASH and advanced fibrosis in patients with NAFLD.[14, 15] Recent studies have suggested that a higher prevalence of NAFLD and more advanced fibrosis may be seen in elderly patients.[16, 17] However, little is known about the characteristics and histology of NAFLD in elderly patients.
The U.S. population is aging due to the steady rise in life expectancy.[18-20] In 2010, ∼40 million Americans were older than 65 years. By the year 2030 this age group of Americans is estimated to rise to more than 70 million. The aging of the American population underscores the importance of studying the characteristics of NAFLD in elderly patients. Finally, a recent study found that alanine aminotransferase (ALT) decreases with age, which may cause significant disease to be overlooked in elderly patients if that is the sole determining criterion for a referral to a specialist.
The main aims of this study were to investigate the clinical and histological characteristics of NASH and fibrosis in elderly patients compared to nonelderly patients from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) cohort, and to determine the characteristics associated with NASH in the elderly compared to nonelderly patients. In this study we hypothesized that elderly patients with NAFLD have more advanced disease, reflected by a higher prevalence of NASH and fibrosis, compared to younger adults.