Impact of AMA positivity in determining the prevalence, incidence and natural history of Primary Biliary Cholangitis in an Italian north-east region

In this retrospective population-based study, the cohort is a complete region in the north-east of Italy that includes 529,940 inhabitants. The study period ranges from 1 January 2007 to July 2019. The records from the immunology laboratory at our Institute were reviewed to identify subjects with positive antimitochondrial antibody (AMA) results. The laboratory of our Institute performs all AMA essays of the whole region, therefore the analysis includes all the AMA positive subjects of the region identified during this period. Then clinical and biochemical informations of all AMA positive subjects will be retrospectively collected since first appearance of AMA by consulting medical reports. Patients will be divided into 2 cathegories: subjects with positivity for AMA and PBC AMA positive patients according to the presence of at least 2 out of the following 3 diagnostic criteria: 1) positive AMA (a titer of at least 1/40); 2) elevation of alkaline phosphatase above the upper limit of normal; and 3) liver histology compatible with PBC. All subjects will be finally contacted to propose a complete clinical, biochemical (standard serum liver tests and serological profiles) and instrumental evaluation (liver stiffness measurement and abodminal ultrasound) and a blood sample to perform the genotypization of the most studied SNPs involved in PBC development. Patients who will consent to be part of the database will be followed-up for 12 months. This will allow them to receive a timely diagnosis, treatment and follow-up according to international guidelines. All data will be entered into an electronic database created specifically for PBC patients to extrapolate epidemiological data about annual incidence and prevalence of the disease, and the percentage of subjects with positivity for AMA antibodies who will develop the disease.