Abstract: When the described search method was used and the eligibility criteria of the search results were applied, 653 records were found. Only two of these were randomised clinical trials that were considered eligible for inclusion. We assessed both trials as trials with high risk of bias. One of the trials was a pilot trial in which 16 participants with biopsy-proven NASH were randomised to receive simvastatin 40 mg (n = 10) or placebo (n = 6) once daily for 12 months. No statistically significant improvement in the aminotransferase level was seen in the simvastatin group compared with the placebo group. Liver histology was not significantly affected by simvastatin. The other trial had three arms. The trial compared atorvastatin 20 mg daily (n = 63) versus fenofibrate 200 mg daily (n = 62) versus a group treated with a combination of the two interventions (n = 61). There were no statistically significant differences between any of the three intervention groups regarding the week 54 mean activity levels of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, and alkaline phosphatase. The triglyceride levels seemed higher in the fenofibrate group compared with the atorvastatin group. Liver histology was not assessed in this trial. The presence of biochemical and ultrasonographic evidence of NAFLD seemed to be higher in the fenofibrate group compared with the atorvastatin group (58% versus 33%). Three patients discontinued treatment due to myalgia and elevated serum creatine kinase activity; one from the atorvastatin group and two from the combination group. Another patient from the atorvastatin group discontinued treatment due to alanine aminotransferase activity that was over three times the upper normal limit. No data for all-cause mortality and hepatic-related mortality were reported in the included trials. Based on the findings of this review, which included two trials with high risk of bias and a small numbers of participants, it seems possible that statins may improve serum aminotransferase levels as well as ultrasound findings. Neither of the trials reported on possible histological changes, liver-related morbidity or mortality. Trials with larger sample sizes and low risk of bias are necessary before we may suggest statins as an effective treatment for patients with NASH. However, as statins can improve the adverse outcomes of other conditions commonly associated with NASH (for example, hyperlipidaemia, diabetes mellitus, metabolic syndrome), their use in patients with non-alcoholic steatohepatitis may be justified.

Plain-language summary: This systematic review identified two randomised clinical trials with very small numbers of participants. One of the trials was a pilot trial and compared simvastatin with placebo, and the other trial assessed atorvastatin versus fenofibrate versus a combination of the two. The small pilot trial (n = 16 patients) assessing simvastatin versus placebo in NASH patients did not show significant effects on liver enzyme activities or liver histology. No adverse events were reported. The other trial compared atorvastatin versus fenofibrate versus a group receiving both interventions in 186 patients with NAFLD. There were no statistically significant differences between any of the three intervention groups regarding the 54 week mean activities of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, or alkaline phosphatases (liver enzymes) in the blood. The triglyceride levels seemed higher in the fenofibrate group compared with the atorvastatin group. Liver histology was not assessed in this trial. The presence of biochemical and ultrasonographic evidence of NAFLD seemed higher in the fenofibrate group compared with the other two intervention groups. Three patients discontinued treatment due to myalgia and elevated serum creatine kinase activity, one from the atorvastatin group and two from the combination group. Another patient from the atorvastatin group discontinued treatment due to raised alanine aminotransferase activity, over three times the upper normal limit. Both trials were at high risk of bias (that is, overestimation of benefits and underestimation of harms). Furthermore, the groups were small raising the risks of random errors (that is, play of chance). Accordingly, we did not find evidence to support or refute the use of statins for patients with NAFLD or NASH. Further unbiased trials with larger numbers of patients looking explicitly at patient-related outcomes of interest (for example, quality of life, development of cirrhosis, and mortality) are needed to assess the effects of statins on NAFLD or NASH.