OBJECTIVE: The aim of this study was to determine the time course over which patients with primary sclerosing cholangitis (PSC) progress through the histological stages of the disease. METHODS: One hundred seven patients with PSC who had at least two liver biopsies were identified. The stage information from two consecutive biopsies formed one observation and a continuous time Markov model was used to describe the rate of progression between biopsies. RESULTS: Three hundred seven liver biopsies were performed in the 107 patients giving a total of 200 observations. At 1 yr, 42% of patients in stage II disease progress, 66% at 2 yr, and 93% at 5 yr; whereas 14% of patients in stage III progress at 1 yr, 25% at 2 yr, and 52% at 5 yr. The frequency of progression of stage I disease could not be determined because of the small number of patients in stage I. Regression of histological stage was observed in 30 of 200 total observations (15%), and in 30 of 85 observations (35%) in which there was a change in stage. CONCLUSIONS: These data regarding histological progression in PSC may be potentially helpful in determining the number of patients and length of time necessary to appreciate a treatment effect in clinical trials. However, the high degree of sampling variability in PSC may restrict the usefulness of serial liver biopsies as a means of evaluating treatment efficacy.
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