A62 CANADIAN POPULATION-BASED EVALUATION OF THE NATURAL HISTORY OF PRIMARY BILIARY CHOLANGITIS OVER THE LAST DECADE

Abstract

Abstract Background Few studies have evaluated the epidemiology of primary biliary cirrhosis (PBC) in North America. Ursodeoxycholic acid (URSO) improves outcomes amongst PBC patients. Aims Therefore, we undertook this study to determine the epidemiology of PBC in Canada, and impact of URSO on clinical outcomes, two decades after URSO approval in North America. Methods We used our previously validated coding algorithm to identify PBC patients in population based administrative databases in the Calgary Health Zone (population ~1.5 million) from 2005–2015. Multiple sources of data including inpatient, ambulatory, physician billing, laboratory, and pharmaceutical were linked. Annual prevalence and incidence were estimated using Poisson regression. Age/sex adjusted rate ratios were calculated. We used Cox regression models to estimate: all-cause mortality, liver transplant and decompensated cirrhosis free survival. In our models, we adjusted for demographic and clinical variables including response to URSO. Results During the study period over 11 years, the overall annual age/sex adjusted PBC incidence was 29.5 cases per million (48.3 and 9.9 per million for women and men, respectively). The highest incidence rate was observed among women aged 60–79 (90.9 per million) with an incidence rate ratio of 10.4 (95%: 6.83–15.9) compared to those aged 20–39. While incidence rate remained stable, prevalence rate increased significantly from 242 to 343 cases/ million, between 2005 and 2015 (P<0.01). Prevalence rate was highest at 965 cases/ million amongst women aged 60–79. We identified 299 incident PBC cases with a median follow up of 5.1 years (IQR 2.9–8.3). 87 (29.1%) of these incident cases developed decompensated cirrhosis or HCC, 10 patients (3.4%) underwent liver transplantation, and 44 (14.7%) patients died. The annual mortality rate was 2.9% (95%CI: 2.1- 3.8) compared to 3.4% (2.3–4.9%) a decade ago (P=0.04). The estimated 5-year survival rate was 87.6% (82.6- 91.3). Standardized mortality rate was 3.2 (95%CI: 2.2–4.1). Overall, 25% of our incident cohort were not prescribed URSO. Patients not prescribed URSO were more likely to be male, older age, have normal ALP and had decompensated cirrhosis at diagnosis (P<0.01 for all). Among those who used URSO, response rate was 86%. Response to URSO was an independent predictor of reduced risk of decompensated cirrhosis and liver transplant, and higher survival (aHR: 0.46, 0.29–0.74). Conclusions PBC prevalence is increasing in this North American population. While mortality rate decreases in our PBC cohort, survival was suboptimal compared to the general population, mainly due to late presentation at diagnosis. Therefore, better surveillance and early detection of possible PBC patients in the primary care setting are essential to improve PBC outcomes. Funding Agencies None