Introduction: While serious liver injury among statin users is extremely rare, baseline liver enzyme testing is still recommended prior to initiating therapy. The benefit of such screening should be reevaluated based on empirical evidence. This study compared the risk of severe acute liver injury (SALI) between statin initiators with an elevated ALT (>35U/L) matched to statin initiators with a normal ALT level (≤35U/L). Statin initiators with an elevated ALT were additionally compared against matched non-users.

Methods: The study created cohorts from Optum and MarketScan claims data. Exposed and comparison cohorts were propensity score (PS) matched in each dataset and findings were pooled using meta-analysis. Proportional hazards regression was used to estimate hazard ratios (HRs), and a prespecified non-inferiority margin for SALI was set at a HR of 1.8.

Results: 232,889 patients with elevated ALT were PS-matched to 232,889 with normal ALT level. The overall incidence rate of SALI was about 19/100,000 person-years among statin initiators. Statin initiators with elevated ALT had no meaningfully increased risk of SALI compared to those with normal ALT (HR=1.15; 95% CI 0.75 to 1.75). Comparing statin initiators with non-initiators with elevated ALT values equally yielded no increased risk (HR=0.76; 95% CI 0.52 to 1.11).

Conclusion: In this large population-based study, SALI in statin users was rare. Importantly, the results showed no evidence that baseline ALT status is a reliable indicator for an increased risk of severe liver injury among statin initiators.