BACKGROUND: The aims of this study were to quantify the histological improvement and its risk factors in patients with NASH enrolled in the placebo arms of randomized controlled trials (RCTs), and to indirectly compare the effect of several investigational drugs for NASH on validated histological outcomes.
DATA SYNTHESIS: A comprehensive search was conducted to detect phase 2 and 3 RCTs comparing pharmacological interventions in patients with NASH. According to Food and Drug Administration (FDA) recommendations, primary outcomes included: 1) NASH resolution without worsening of fibrosis; 2) At least 1-point reduction in fibrosis without worsening of NASH. Meta-analysis and meta-regressions were conducted on placebo arms, while network meta-analysis was performed on intervention arms. A total of 15 RCTs met the eligibility criteria. The meta-analysis on placebo arms showed a pooled estimate rate of 17% (95%C.I. 12%-23%;I = 86%; p < 0.01) for NASH resolution without worsening of fibrosis and of 21% (95%C.I. 13%-31%;I = 84%; p < 0.01) for ≥1stage improvement of fibrosis without worsening of NASH. Phase 3 (vs Phase 2)RCTs, older age and higher AST levels were significantly associated with progression of liver disease by univariate meta-regression. At network meta-analysis, Semaglutide (P-score 0.906), Pioglitazione alone (score 0.890) and plus Vitamin E (0.826) had the highest probability of being ranked the most effective intervention for NASH resolution without worsening of fibrosis, while Aldafermin (0.776), Lanifibranor (0.773) and Obeticholic acid (0.771) had the highest probability to achieve ≥1 stage of fibrosis improvement without worsening of NASH.
CONCLUSION: This study confirms the heterogeneity of histological progression of untreated patients with NASH and provides evidence to stratify patients according to identified risk factors in future RCTs of combination therapies. PROSPERO CRD42021287205.