Obstructive sleep apnea, chronic obstructive pulmonary disease and NAFLD: an individual participant data meta-analysis

RATIONALE: Chronic intermittent hypoxia occurring in obstructive sleep apnea (OSA) is independently associated with nonalcoholic fatty liver disease (NAFLD). Chronic obstructive pulmonary disease (COPD) has also been suggested to be linked with liver disease. OBJECTIVE: In this individual participant data meta-analysis, we investigated the association between liver damage and OSA and COPD severity. METHODS AND MEASUREMENTS: Patients suspected of OSA underwent polysomnography (PSG) or home sleep apnea testing (HSAT). Non-invasive tests were used to evaluate liver steatosis (Hepatic Steatosis Index) and fibrosis (Fibrotest or FibroMeter). An individual participant data meta-analysis approach was used to determine if the severity of OSA/COPD affects the type and severity of liver disease. Results were confirmed by multivariate and causal mediation analysis. Sub-group analyses were performed to investigate specific populations. MAIN AHI severity was not associated with fibrosis. A combination of AHI >30/h and COPD stage 1 was associated with an increased risk of steatosis. CONCLUSION: This meta-analysis confirms the strong association between steatosis and the severity of OSA. The relation between OSA and fibrosis is mainly due to BMI as shown by causal mediation analysis.