Pares 2000.

Methods	Double‐blind, placebo controlled randomised clinical trial with parallel group design (two interventions groups). Trial duration: at least 2 years (median follow‐up was 3.4 years). Follow‐up: 10 ursodeoxycholic acid treated patients and 21 placebo treated patients discontinued.
Participants	Country: Spain. Number of patients randomised: 192, from 16 hospitals in Spain, mean age 54 years (93% females). Inclusion criteria: ‐ compatible liver biopsy; ‐ alkaline phosphatase > 2 upper normal limit; ‐ positive antimitochondrial antibodies; ‐ patients with negative antimitochondrial antibodies were accepted if there was no evidence of extrahepatic biliary obstruction. Exclusion criteria: ‐ age > 72 years; ‐ previous PBC treatment in the 6 months before entry; ‐ life expectancy less than 6 months; ‐ drug addiction; ‐ pregnancy; ‐ other cause of liver disease.
Interventions	Patients were randomly assigned to receive: Intervention group 1: ursodeoxycholic acid 14 to 16 mg/kg/day in three divided doses, n = 99; Intervention group 2: no intervention, n = 93.
Outcomes	Mortality. Liver transplantation. Symptoms. Complications. Liver biochemistry. Liver histology. Adverse events.
Notes	Data for liver biopsy findings ‐ dichotomous variables outcome were extracted from Pares 2001 (Pares 2000). Additional information requested on 26th January 2012 and reply received on 31st January 2012 through personal communication with the principal author Dr. Albert Pares who provided data on the method of sequence generation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Patients were randomised to take ursodeoxycholic acid or placebo (ratio 1: 1), using a randomisation code generated by computer.
Allocation concealment (selection bias)	Low risk	Allocation was controlled by serially numbered sealed and opaque envelopes.
Blinding (performance bias and detection bias) All outcomes	Low risk	The trial was described as blinded, the parties that were blinded, and the method of blinding was described ('placebo was identical in appearance, smell, and taste'), so that knowledge of allocation was adequately prevented during the trial.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The numbers and reasons for dropouts and withdrawals in all intervention groups were described.
Selective reporting (reporting bias)	Low risk	Pre‐defined, or clinically relevant and reasonably expected outcomes are reported on.
Other bias	Unclear risk	It was reported that trial medications were provided by Zambon S. A., Laboratorio Farmaceutico.