Aspirin for Metabolic Dysfunction–Associated Steatotic Liver Disease Without Cirrhosis

Importance: Aspirin may reduce severity of metabolic dysfunction-associated steatotic liver disease (MASLD) and lower the incidence of end-stage liver disease and hepatocellular carcinoma, in patients with MASLD. However, the effect of aspirin on MASLD is unknown. Objective: To test whether low-dose aspirin reduces liver fat content, compared with placebo, in adults with MASLD. Design, Setting, and Participants: This 6-month, phase 2, randomized, double-blind, placebo-controlled clinical trial was conducted at a single hospital in Boston, Massachusetts. Participants were aged 18 to 70 years with established MASLD without cirrhosis. Enrollment occurred between August 20, 2019, and July 19, 2022, with final follow-up on February 23, 2023. Interventions: Participants were randomized (1:1) to receive either once-daily aspirin, 81 mg (n = 40) or identical placebo pills (n = 40) for 6 months. Main Outcomes and Measures: The primary end point was mean absolute change in hepatic fat content, measured by proton magnetic resonance spectroscopy (MRS) at 6-month follow-up. The 4 key secondary outcomes included mean percentage change in hepatic fat content by MRS, the proportion achieving at least 30% reduction in hepatic fat, and the mean absolute and relative reductions in hepatic fat content, measured by magnetic resonance imaging proton density fat fraction (MRI-PDFF). Analyses adjusted for the baseline value of the corresponding outcome. Minimal clinically important differences for study outcomes were not prespecified. Results: Among 80 randomized participants (mean age, 48 years; 44 [55%] women; mean hepatic fat content, 35% [indicating moderate steatosis]), 71 (89%) completed 6-month follow-up. The mean absolute change in hepatic fat content by MRS was -6.6% with aspirin vs 3.6% with placebo (difference, -10.2% [95% CI, -27.7% to -2.6%]; P = .009). Compared with placebo, aspirin treatment significantly reduced relative hepatic fat content (-8.8 vs 30.0 percentage points; mean difference, -38.8 percentage points [95% CI, -66.7 to -10.8]; P = .007), increased the proportion of patients with 30% or greater relative reduction in hepatic fat (42.5% vs 12.5%; mean difference, 30.0% [95% CI, 11.6% to 48.4%]; P = .006), reduced absolute hepatic fat content by MRI-PDFF (-2.7% vs 0.9%; mean difference, -3.7% [95% CI, -6.1% to -1.2%]; P = .004]), and reduced relative hepatic fat content by MRI-PDFF (-11.7 vs 15.7 percentage points; mean difference, -27.3 percentage points [95% CI, -45.2 to -9.4]; P = .003). Thirteen participants (32.5%) in each group experienced an adverse event, most commonly upper respiratory tract infections (10.0% in each group) or arthralgias (5.0% for aspirin vs 7.5% for placebo). One participant randomized to aspirin (2.5%) experienced drug-related heartburn. Conclusions and Relevance: In this preliminary randomized clinical trial of patients with MASLD, 6 months of daily low-dose aspirin significantly reduced hepatic fat quantity compared with placebo. Further study in a larger sample size is necessary to confirm these findings. Trial Registration: ClinicalTrials.gov Identifier: NCT04031729.