CPAP unlikely to improve nonalcoholic fatty liver disease in patients with sleep apnea

CPAP alone did not improve hepatic steatosis and fibrosis in patients with nonalcoholic fatty liver disease and obstructive sleep apnea, researchers reported in the American Journal of Respiratory and Critical Care Medicine.

“In recent years, the common pathogenic mechanisms in NAFLD and OSA have attracted much research interest and stimulated studies of the effects of chronic intermittent hypoxemia and OSA-related parameters to the severity of NAFLD,” Susanna S.S. Ng, MBChB, assistant professor in the department of medicine and therapeutics at The Chinese University of Hong Kong and SH Ho Sleep Apnea Management Center, and colleagues wrote.

Researchers evaluated 120 patients with NAFLD and OSA, which was defined by respiratory event index of 5 or more hours. Patients were randomly assigned to an auto-adjusting CPAP group (n = 60; mean age, 55 years; 51.7% men), with a pressure range of 4 cm to 20 cm H₂O, or a subtherapeutic CPAP group (n = 60; mean age, 55 years; 61.7% men), with the pressure fixed at 4 cm H₂O.

The primary endpoint, difference in changes in intrahepatic triglyceride measured by proton magnetic resonance spectroscopy, was not different after 6 months of CPAP therapy. The researchers reported no significant difference in absolute values of intrahepatic triglycerides between the auto-adjusting CPAP group and the subtherapeutic CPAP group (0.7% vs. 0.7%; P = .0966) and percentage change (22.5% vs. 14%; P = .465) in the intention-to-treat analysis. There was also no difference between groups in the treatment-per-protocol analysis (absolute values: 0.7% vs. 0.3%; P = .694; percentage change: 23% vs. 6.6%; P = .144), according to the results.

In addition, there were no significant differences in changes in secondary endpoints, including controlled attenuation parameter and liver stiffness measured by transient elastography, after 6 months of treatment.

Researchers observed correlations between CPAP and respiratory event index (P = .026), percentage of total recording time with oxygen saturation less than 90% (P = .003) and oxygen desaturation index (P = .019). Weight change over 6 months was correlated with changes in intrahepatic triglycerides and controlled attenuation parameter (P < .001). Patients in the auto-adjusting CPAP group had more weight gain (1.7 vs. –0.1; P = .009) during the study period.

“CPAP alone is unlikely to alter NAFLD activities in patients with concomitant OSA and the additional role of weight reduction through lifestyle modifications deserves further investigation,” the researchers wrote.