Background: The association of obstructive sleep apnea (OSA) with nonalcoholic fatty liver disease (NAFLD) has only been studied in selected subgroups such as the morbidly obese. We aimed to determine the prevalence and effect of OSA on NAFLD and vice versa in unselected patients attending the outpatient department.
Methods: OSA was diagnosed by polysomnography, done in patients having symptoms of OSA, in patients with NAFLD attending the liver clinic. Polysomnography-proven patients with OSA attending the chest clinic were evaluated for NAFLD by ultrasonography. Anthropometry, liver function tests, metabolic syndrome evaluation and transient elastography were performed in all patients.
Results: Three (3%; 95% CI 1.03-8.45%) out of 100 patients with NAFLD (mean age 41 ± 11 years) had symptomatic OSA. Of 23 patients with OSA (mean age 46 ± 12 years,), 3 (13%) had mild, 5 (22%) moderate and 15 (65%) severe OSA. Twenty-one (91.3%; 95% CI 73.2-97.6%) patients with OSA had NAFLD, while raised hepatic transaminase levels were seen in seven (30.4%; 95% CI 15.6-50.9%). Body mass index (OR 1.21, 95% CI 1.02-1.44) and male gender (OR 4.79, 95% CI 1.12-20.48) were significant independent predictors of OSA in NAFLD. The apnea-hypopnea index (OR 1.084, 95% CI 1.002-1.172), a marker of OSA severity, was the only significant independent predictor of significant fibrosis in patients with NAFLD.
Conclusions: Prevalence of symptomatic OSA in patients with NAFLD is low and is predicted by male gender and obesity. Prevalence of NAFLD in patients with OSA is very high. Significant hepatic fibrosis in patients with NAFLD is predicted by OSA independent of obesity and metabolic syndrome.