Sanchez‐Tapias 2006.

Methods	Randomised clinical trial. Study design: patients with chronic HCV infection without RVR (after 4 weeks of treatment) were randomised to continue therapy for 44 additional weeks or for 68 additional weeks. Duration of follow‐up: 24 weeks after the end of treatment.
Participants	Location: 28 specialist hepatology centres in Spain. Time of participants selection: 4‐9/2001. Included participants in our meta‐analysis: chronic hepatitis C genotype 1 naive patients with detectable HCV RNA at week 4. No. participants: 149 in the 48‐week treatment group and 142 in the 72‐week treatment group. Mean age: no data. Males: no data. Mean BMI: no data Liver biopsy: preformed within the past two years consistent with chronic hepatitis.
Interventions	Experimental: s.c. peginterferon alfa‐2a 180 µg/week and p.o. ribavirin 800 mg*1/d for 72 weeks. Control: s.c. peginterferon alfa‐2a 180 µg/week and p.o. ribavirin 800 mg*1/d for 48 weeks.
Outcomes	Outcomes and time points considered in the review Primary outcome: SVR. Additional data that were extracted: end of treatment response; relapse rate. Outcomes and time points not considered in the review: the influence of baseline viraemia less than 800,000 IU/mL on SVR; predictive value of the on‐treatment virologic response (defined as an undetectable serum HCV‐RNA level or a 2 log10 or more decrease from baseline in serum HCV RNA levels at weeks 12 or 24 of treatment). Safety and adherence data about participants from all four genotypes.
Notes	A total of 510 chronic HCV naive patients (genotype 1, 2, 3, 4) underwent evaluation at week 4 of treatment: 326 were slow responders/non RVR and were randomised to 48 or 72 weeks' treatment, 184 were RVR and were randomised to 24 or 48 weeks treatment. Among the slow responders 291 were genotype 1 patients.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	participants were randomly allocated. "The computerized randomisation list (by blocks of 4 patients, without stratification) was generated automatically by SAS software".
Allocation concealment (selection bias)	Low risk	"PRA‐Staticon International S.L. (Madrid, Spain) managed the centralized randomisation procedure, maintained the randomisation list, and communicated with study centers by phone and confirmed by fax".
Blinding (performance bias and detection bias) All outcomes	High risk	There was no blinding.
Incomplete outcome data (attrition bias) All outcomes	High risk	There was not isolated available data about genotype 1 participants regarding number of slow responders that completed therapy, number of slow responders in which treatment reduction was needed or therapy was discontinued due to adverse events, and about the rate of serious adverse events in slow responders.
Selective reporting (reporting bias)	High risk	No clinical data on mortality were reported.
Other bias	Unclear risk	The authors used fixed blocked randomisation in an unblinded trial, so it might be possible to predict future assignments. Sponsored by the industry.

EVR = early virological response 
 HCV = hepatitis C virus 
 p.o. = peroral 
 RNA = ribonucleic acid 
 s.c. = subcutaneous 
 SVR = sustained virological response