Epidemiology and natural history of primary biliary cirrhosis in a Canadian health region: A population-based study

Abstract

The recent epidemiology and outcomes of primary biliary cirrhosis (PBC) in North America are incompletely described, partly due to difficulties in case ascertainment. In light of their availability, broad coverage, and limited expense, administrative databases may facilitate such investigations. We used population-based administrative data (inpatient, ambulatory care, and physician billing databases) and a validated International Classification of Diseases coding algorithm to describe the epidemiology and natural history of PBC in the Calgary Health Region (population approximately 1.1 million). Between 1996 and 2002, the overall age/sex-adjusted annual incidence of PBC was 30.3 cases per million (48.4 per million in women, 10.4 per million in men). Although the incidence remained stable, the prevalence increased from 100 per million in 1996 to 227 per million in 2002 (P < 0.0005). Among 137 incident cases with a total follow-up of 801 person-years from diagnosis (median 5.8 years), 27 patients (20%) died and six (4.4%) underwent liver transplantation. The estimated 10-year probabilities of survival, liver transplantation, and transplant-free survival were 73% (95% confidence interval [CI] 60%-83%), 6% (95% CI 2.5%-12.6%), and 68% (95% CI 55%-78%), respectively. Survival in PBC patients was significantly lower than that of the age/sex-matched Canadian population (standardized mortality ratio 2.87; 95% CI 1.89-4.17); male sex (hazard ratio [HR] 3.80; 95% CI 1.85-7.82) and an older age at diagnosis (HR per additional year, 1.06; 95% CI 1.03-1.10) were independent predictors of mortality. This population-based study demonstrates that the burden of PBC in Canada is high and growing. Survival of PBC patients is significantly lower than that of the general population, emphasizing the importance of developing new therapies for this condition.