Factors influencing longitudinal changes of circulating liver enzyme concentrations in subjects randomized to placebo in four clinical trials.

Liver enzyme concentrations are measured as safety endpoints in clinical trials to detect drug-related hepatotoxicity, but little is known about the epidemiology of these biomarkers in subjects without hepatic dysfunction who are enrolled in drug trials. We studied alanine and aspartate aminotransferase (ALT, AST) in subjects randomized to placebo who completed assessments over 36 months in a cardiovascular outcome trial (the 'STABILITY' trial; n=4264; mean age: 64.2 yr) or over 12 months in 3 trials that enrolled only subjects with type 2 diabetes (T2D) (the 'DIA' trials; n=308; mean age: 62.4 yr) to investigate time-dependent relationships and the factors that might affect ALT and AST, including body mass index (BMI), T2D and renal function. Multivariate linear mixed models examined time-dependent relationships between liver enzyme concentrations as response variables, and BMI, baseline T2D status, hemoglobin A1c levels and renal function, as explanatory variables. At baseline, ALT was higher in individuals who were males, < 65 years old, obese and who had GFR > 60 mL/min/1.73m2 . ALT was not significantly associated with T2D at baseline, although it was positively associated with HbA1c . GFR had a greater impact on ALT than T2D. ALT concentrations decreased over time in subjects who lost weight, but remained stable in individuals with increasing BMI. Weight change did not alter AST concentrations. We provide new insights on the influence of time, GFR and HbA1c on ALT and AST concentrations and confirm the effect of gender, age, T2D, BMI and BMI change in subjects receiving placebo in clinical trials.