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

Abstract

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 Örebro 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.

Familial associations between autoimmune hepatitis and primary biliary cholangitis and other autoimmune diseases

“…For PBC, the high concordant association of about 10 was in line with the population-based Icelandic data [15]. AH and PBC showed shared familial associations with each other, the SIRs being 2.21 and 2.47, which is in line with polyautoimmunity between these AIDs [5]. AH and PBC shared any significant bidirectional associations with 10 other AIDs, most of which were lower than those between AH and PBC, suggesting that the two liver AIDs share somewhat more with each other than with extrahepatic AIDs.…”

“…Another limitation is that we have no information on co-morbidities in the study population because only the first AID was considered for each person to simplify the family study. However, the previous Swedish studies on AH and PBC report such data and the population in the PBC study is overlapping with the present one [3,5]. A further weakness was the definition of spouses which was based on the first common child and would not tell which of the couples subsequently divorced.…”

“…However, in Sweden where medical care is practically free of charge, diagnostics and treatment at the specialist level are largely conduced at inpatient or outpatient wards in hospitals. The reported prevalence in PBC was among the highest in the world from the overlapping patient population, suggesting that the coverage of patients was high (5). The strengths of the study were diagnostics in a standard way in a high-level health care system, accessible to the population at large without economic barriers.…”

“…The clinical presentation may vary substantially, ranging from an asymptomatic elevation of liver enzymes to acute liver failure. Diagnostic guidelines of the European Association for the Study of the Liver (EASL) are applied in Sweden (5). First-line therapy is immunosuppression for AH and ursodeoxycholic acid for PBC; in advance cases liver transplantation may be required [1,9].…”

Clinical Updates in Primary Biliary Cholangitis: Trends, Epidemiology, Diagnostics, and New Therapeutic Approaches

“…7,16,19 Recently, a large population-based analysis of both inpatient and outpatient registries in Sweden found that the prevalence of PBC increased steadily from 5.0 to 34.6 per 100,000 persons from 1987 to 2014, respectively. 20 Data collected from an Italian cohort between 2014 to 2015 reported that the point-prevalence of PBC was 27.9 per 100,000 people in Italy. 21 In addition to the scarcity of large population-based studies, misdiagnoses and underreporting of patients may also contribute to the incidence and prevalence of PBC, as 5-10% of patients may be antimitochondrial antibody (AMA)negative.…”