Liver enzymes and histology in obese patients with obstructive sleep apnea

BACKGROUND AND AIMS: Recent studies have shown an association between obstructive sleep apnea (OSA) and elevated liver enzymes in patients with nonalcoholic fatty liver disease (NAFLD). The aim of the current study was to compare biochemical and histologic findings in patients with NAFLD as a function of OSA status. METHODS: Subjects consisted of 85 patients who had a sleep study followed by a liver biopsy performed at the time of obesity surgery. The diagnosis of OSA was based on an apnea hypopnea index of >/=15. Demographic and laboratory data were collected retrospectively. Liver biopsies were systematically evaluated for features of NAFLD including degree of steatosis, inflammation, and fibrosis. RESULTS: All but one patient had histologic evidence of NAFLD and 51% of the study population had OSA. A higher proportion of patients with OSA had elevated alanine aminotransferase levels (13/39) compared with those without OSA (3/34) (P=0.01). Only 19% of subjects had fibrosis on liver biopsy and still fewer (5%) had bridging fibrosis or cirrhosis. There was a trend toward a higher prevalence of OSA in patients with evidence of progressive liver disease, as indicated by inflammation plus fibrosis (11/15), compared with those with inflammation alone (22/48) (P=0.06). CONCLUSIONS: In obese patients with NAFLD, OSA was associated with elevated alanine aminotransferase levels and a trend toward histologic evidence of progressive liver disease.