Incidence, prevalence, and outcome of primary biliary cholangitis in a nationwide Swedish population-based cohort

Available epidemiological data on primary biliary cholangitis (PBC) in Sweden originate from regional studies in the 1980s and may not reflect modern day PBC. We aimed to estimate incidence and prevalence, survival and death causes, and gender differences in PBC. We used international classification of disease (ICD) codes to identify patients with PBC in inpatient and outpatient registries 1987-2014 who were then linked to the Swedish cause of death, cancer and prescribed drug registries. Each PBC patient was matched with 10 reference individuals from the general population. In sensitivity analyses, we examined PBC patients identified through clinical patient records from Karolinska, Sahlgrenska and Orebro University Hospitals. We identified 5,350 adults with PBC. Prevalence of PBC increased steadily from 5.0 (1987) to 34.6 (2014) per 100,000 inhabitants whereas the yearly incidence rate was relatively constant with a median of 2.6 per 100,000 person-years, with a female: male gender ratio of 4:1. Compared to reference individuals, PBC individuals aged 15-39 years at diagnosis had a substantially higher risk of death (Hazard Ratio [HR] 12.7, 95% Confidence Interval [CI] 8.3-19.5) than those diagnosed between 40-59 (HR 4.1, 95% CI 3.7-4.5) and > 60 (HR 3.7, 95% CI 3.5-3.9) years of age. Relative risks of mortality were highest in men. In conclusion, we found that recorded prevalence of PBC in Sweden has increased substantially during the last 30 years although incidence has been stable. Patients diagnosed in young adulthood were at a 12.7-fold increased risk of death, and male PBC patients had worse prognosis.