Summary Background Alkaline phosphatase (ALP) is an important serum marker in primary sclerosing cholangitis (PSC). Patients with obstruction of the large bile ducts due to dominant strictures (DS) are a special, clinically important phenotype. Aim To determine the impact of ALP reduction on liver transplantation‐free survival in PSC patients with DS. Methods Prospective cohort study in 215 PSC patients. We performed subgroup analysis for patients without DS (no DS, n = 84), DS at first presentation (DS early, n = 72) and development of DS during the course of the study (DS late, n = 59). We evaluated two scores of ALP reduction. ALP reduction 1 was defined as ALP normalisation, 50% reduction compared with baseline values, or reduction below 1.5 times of upper limit of normal (ULN) within 6 months. ALP reduction 2 was defined as ALP reduction below 1.5 times of ULN within 12 months. Results Of the patients, 59.5% reached an ALP reduction 1 and 56.7% according to ALP reduction 2. Achievement of each score was associated with longer transplantation‐free survival in all three groups (ALP reduction 1: no DS P = 0.001; DS early P < 0.001; DS late P = 0.022; ALP reduction 2: no DS P = 0.014; DS early P = 0.001; DS late P = 0.002). Cox‐regression analysis revealed each score as an independent predictor for improved transplantation‐free survival (ALP reduction 1 and 2 P < 0.001 each). We further analysed previously published scores of ALP improvement in PSC showing also improved survival in patients with ALP normalisation or a reduction below 1.5 times of ULN (P = 0.003, P = 0.001, respectively), whereas the score determined by 40% reduction did not show significant differences in survival (P = 0.55). Conclusions Reduction in alkaline phosphatase values within the first year is associated with improved transplantation‐free survival in patients with primary sclerosing cholangitis independent of the presence of dominant strictures. Alkaline phosphatase might be an adequate surrogate marker for outcome assessment in clinical studies both for patients with and without dominant strictures.

Recently, the MRI working group of the International PSC Study Group (IPSCSG) has published a position statement on the use of MRI regarding diagnosis and follow-up of PSC patients. These guidelines are intended for use by physicians in daily clinical routine. In addition, the group has outlined several areas of research, which need to be addressed in the near future. As PSC is a rare disease with the clinical outcome being determined by the development of end-stage liver disease and hepatobiliary malignancy. This article is protected by copyright. All rights reserved.