Determining and predicting biochemical disease trajectory in intrahepatic cholestasis of pregnancy: A longitudinal cohort study

Background The severity of intrahepatic cholestasis of pregnancy (ICP) reflects peak maternal bile acid (BA) concentration. However, the course of the disease is unclear. Methods Longitudinal observational cohort study of individuals with ICP. Serial BA and alanine aminotransferase (ALT) trajectories were determined according to starting severity. Multiple logistic regression identified variables predictive of subsequent disease severity, validated using data from a randomised controlled trial. Results Although highly variable, BA concentrations increased across gestation ( p > 0.001). Normal ALT concentration at diagnosis predicted concurrent non-severe disease (negative predictive value 94.2% (91.6–96.1%)). Gestational age and BA concentration at diagnosis somewhat predicted later moderate or severe disease (BA ≥ 40 µmol/L: ROCAUC 0.64 (0.58–0.69); BA ≥ 100 µmol/L: ROCAUC 0.68 (0.62–0.73)), similarly in the validation cohort (ROCAUC 0.70 (0.65–0.76) and 0.69 (0.63–0.76), respectively). Conclusion An earlier gestation and higher BA concentration at diagnosis increase the likelihood of more severe disease; however robust prediction is limited.