Table 2.

Studies showing beneficial impact of continuous positive airway pressure in subjects with obstructive sleep apnea and nonalcoholic fatty liver disease

Reference	Study Design	Study Population; Country	Duration of CPAP Therapy	Findings
Impact on liver enzymes
Chin et al,87 2003	Prospective cohort study	40 men; Japan	6 mo	CPAP therapy had beneficial effects on serum aminotransferase abnormalities in obese OSA subjects.
Shpirer et al,88 2010	Prospective cohort study	11 subjects; Israel	3 y	Significant reduction in liver enzyme levels and improvement in the mean liver attenuation index in CPAP subjects (n = 6) compared with control group (n = 5).
Hobzova et al,89 2015	Prospective cohort study	179 subjects; Czech Republic	13 mo	Significant positive effect on liver enzymes in subjects with moderate to severe OSA.
Kim et al,90 2018a	Retrospective cohort study	351 subjects; California	6 mo	CPAP treatment was associated with significant biochemical improvement in liver enzymes.
Chen et al,93,101 2018	Prospective cohort study	160 subjects; China	3 mo	CPAP therapy was significantly associated with improvement of ALT and AST levels.
Sundaram et al,100 2018	Prospective cohort study	9 subjects; USA	3 mo	CPAP treatment reduces alanine aminotransferase, metabolic syndrome markers, and F (2)-isoprostanes.
Chen et al,93,101 2018	Meta-analysis	5 studies	—	CPAP was associated with a statistically significant decrease in the liver enzyme levels in OSA subjects.
Impact on liver steatosis
Yoshiro et al,94 2014	Retrospective cohort study	61 male subjects; Japan	31 mo	In male OSA subjects with abdominal obesity, significant decrease in liver fat content was observed after long-term CPAP therapy, only when fatty liver was present at baseline.
Buttacavoli et al,95 2016	Observational study	15 subjects (3 at 6 mo and 15 at 12 mo follow-up)	6 and/or 12 mo	Long-term CPAP treatment may improve liver steatosis.
Impact on fibrosis
Mesarwi et al,80 2015	Prospective cohort study	35 subjects; Brazil	3 mo	A reduction in serum LOX (an enzyme that cross-links collagen and can serve as a biomarker of hepatic fibrosis) was seen in OSA subjects on CPAP.
Hang et al,99 2017	Retrospective cohort study	Propensity-matched 5214 subjects; Taiwan	2–10 y	CPAP plays an important role in the delay of the progression of liver disease in OSA subjects and decreases the incidence of liver disease among these groups of subjects.
Kim et al,90 2018a	Retrospective cohort study	351 subjects; California	6 mo	CPAP treatment was associated with reduction in NAFLD-related fibrosis.

^aRepresents same study with findings in 2 different headings.