Epidemiology

Severe sleep apnea may damage liver

Last Updated: 2005-05-26 12:15:55 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Severe obstructive sleep apnea (OSA) appears to be a risk factor for liver damage, regardless of whether or not a patient is obese, French investigators report in the June issue of Hepatology.

Senior author Dr. Lawrence Serfaty and colleagues hypothesized that "OSA-induced insulin resistance and direct liver hypoxia could possibly be involved in the pathogenesis of liver disease associated with OSA."

To test their theory, Dr. Serfaty's group evaluated 163 patients referred to the Sleep Unit at Hospital Saint-Antoine in Paris for clinical suspicion of OSA. None of the subjects consumed alcohol. Polysomnography showed that 44 had severe OSA (apnea hypopnea index (AHI) > 50/hour), 84 had moderate OSA (AHI 10 to 50/hour) and 35 had no evidence of OSA.

Further testing revealed that liver enzymes were elevated in 14 (32%) of those with severe OSA, 15 (18%) of those with moderate OSA and 3 (8.6%) with no OSA (p = 0.02). Multivariate analysis showed that BMI and severe OSA were independent risk factors for elevated liver enzymes.

Liver biopsies were performed in 18 of those with elevated liver enzymes (9 with severe OSA, 6 with moderate OSA and 3 with no OSA).

Eight of those with severe OSA had steatohepatitis versus four of those with moderate or no OSA (P = 0.04). Severe OSA was also associated with a higher degree of lobular necrosis and fibrosis. All three conditions, along with insulin resistance, correlated with AHI, independent of age and BMI

"Promotion of insulin resistance is likely to be involved in the pathogenesis of liver injury," the authors suggest.

"OSA is a risk factor for abnormal liver enzymes independent of BMI and should be investigated in patients without other cause of liver disease," they conclude. They recommend further studies to assess the prevalence of OSA in patients with nonalcoholic steatohepatitis "and to evaluate whether treatment of OSA may improve liver injury."

Hepatology 2005;41:1290-1296.