The Natural History of Asymptomatic Gallstones A Longitudinal Study and Prediction Model

BACKGROUND & AIMS: Despite the high prevalence of asymptomatic gallstones (AGs), there are limited data on their natural history. We aimed to determine the rate of symptom development in a contemporary population, determine factors associated with progression to symptomatic gallstones (SGs), and develop a clinical prediction model.METHODS: We used a retrospective cohort design. The time to first SG was shown using Kaplan-Meier curves. Multivariable competing risk (death) regression analysis was used to identify vari-ables associated with SGs. A prediction model for the development of SGs after 10 years was generated and calibration curves were plotted. Participants were patients with AGs based on ultrasound or computed tomography from the general medical population. RESULTS: From 1996 to 2016, 22,257 patients (51% female) with AGs were identified; 14.5% developed SG with a median follow-up period of 4.6 years. The cumulative incidence was 10.1% (& PLUSMN;0.22%) at 5 years, 21.5% (& PLUSMN;0.39%) at 10 years, and 32.6% (& PLUSMN;0.83%) at 15 years. In a multivariable model, the strongest predictors of developing SGs were female gender (hazard ratio [HR], 1.50; 95% CI, 1.39-1.61), younger age (HR per 5 years, 1.15; 95% CI, 1.14-1.16), multiple stones (HR, 2.42; 95% CI, 2.25-2.61), gallbladder polyps (HR, 2.55; 95% CI, 2.14-3.05), large stones (HR, 2.03; 95% CI, 1.80-2.29), and chronic hemolytic anemia (HR, 1.90; 95% CI, 1.33-2.72). The model showed good discrimination (C-statistic, 0.70) and calibration. CONCLUSIONS: In general medical patients with AGs, symptoms developed at approximately 2% per year. A predictive model with good calibration could be used to inform patients of their risk of SGs.