Study	Reason for exclusion
Adinolfi 2003	RCT comparing different ribavirin plus interferon regimens.
Aghemo 2012	Editorial review of Lok paper from HALT‐C trial
Akham 2011	Uncontrolled trial.
Alaimo 2006	RCT comparing different ribavirin plus interferon regimens.
Alberti 1997	Meta‐analysis.
Almasio 1999	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Andreone 1999	RCT comparing interferon versus interferon and ribavirin regimen.
Andreone 2000	RCT comparing interferon versus interferon and ribavirin regimen.
Arase 1994	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Arase 2003	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
August‐Jörg 2003	RCT comparing different ribavirin plus interferon regimens.
Azzaroli 2004	RCT comparing combination therapy to no treatment in treatment naive patients.
Bapin 2004	RCT comparing different ribavirin plus interferon regimens.
Barbaro 1998	RCT comparing interferon versus interferon and ribavirin regimen.
Barbaro 1999	RCT comparing interferon versus interferon and ribavirin regimen.
Barbaro 1999 b	RCT comparing interferon versus interferon and ribavirin regimen.
Bekkering 1998	Uncontrolled study.
Bell 1999	RCT comparing interferon versus interferon and ribavirin regimen.
Bellobuono 1997	RCT comparing interferon versus interferon and ribavirin regimen.
Berg 2006	RCT comparing interferon plus ribavirin in treatment‐naive patients.
Bergmann 2007	RCT comparing different ribavirin plus interferon regimens.
Bernardinello 1999	RCT comparing beta‐interferon to no therapy.
Bonkovsky 1996	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Bresci 2000	RCT comparing interferon versus interferon and ribavirin regimen.
Bresci 2000b	RCT comparing interferon versus interferon and ribavirin regimen.
Brillanti 1994	RCT comparing interferon versus interferon and ribavirin regimen.
Brillanti 1995	RCT comparing interferon versus interferon and ribavirin regimen.
Buti 2000	RCT comparing different ribavirin plus interferon regimens.
Böcher 2006	RCT comparing different ribavirin plus interferon regimen.
Cagnoni 1999	Uncontrolled study.
Carr 2007	Two RCTs comparing different ribavirin plus interferon regimens.
Carrara 1998	Uncontrolled study.
Cavalletto 2000	RCT comparing interferon versus interferon and ribavirin regimen.
Chapman 2001	RCT comparing interferon versus interferon and ribavirin regimen.
Chemello 1997	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Chousterman 2003	RCT comparing different ribavirin plus interferon regimen.
COPILOT 2008	COPILOT RCT; however, control group received colchicine, not no therapy or placebo
Cornberg 2006	RCT comparing different ribavirin plus interferon regimens.
Cotler 1997	Observational study.
Cuccorese 2000	Uncontrolled study.
Davis 1998	RCT comparing interferon versus interferon and ribavirin regimen.
Davis 1999	Selected subpopulation of patients randomized (only complete and partial responders to a repeat course of interferon were randomized; nonresponders were not randomized).
Di Biceglie 2000	RCT comparing interferon plus iron reduction versus interferon.
Di Bisceglie 2001	RCT comparing different ribavirin plus interferon regimens.
Di Marco 2000	RCT comparing different ribavirin plus interferon regimens.
Diago 2007	RCT comparing different ribavirin plus interferon regimens.
Dollinger 2005	RCT comparing different ribavirin plus interferon regimens.
Enriquez 2000	RCT comparing different ribavirin plus interferon regimens.
Erdem 2002	RCT comparing different ribavirin plus interferon regimens.
Fargion 2006	RCT comparing different ribavirin and amantadine plus interferon regimens.
Fartoux 2007	RCT comparing IFN to no treatment, but not all patients were being retreated and unable to obtain information regarding data just for retreated ones.
Fattovich 2003	RCT comparing different ribavirin plus interferon regimens.
Ferenci 1996	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Fong 2000	Insufficient data for inclusion. The dose and duration of previous interferon therapy is not described. Also, only 12‐week response rates are reported, but no end of treatment (48‐week) data are available.
Fontagnes 2007	Non‐randomized trial.
Gaeta 1997	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Gerken 1995	Uncontrolled study.
Getachew 2004	RCT comparing different ribavirin plus interferon regimens.
Giudici‐Cipriani 1993	Non‐randomized study.
Gross 1999	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Guerret 1999	Observational study.
Hadziyannis 1997	Insufficient data for inclusion. The dose and duration of previous interferon therapy are not described, nor is the number of patients in each intervention group.
Hasan 2001	Uncontrolled study.
Hass 2005	Uncontrolled study.
Heathcote 1998	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Horiike 1994	Non‐randomized study.
Iino 2002	RCT including both naive patients and patients who had previously received interferon.
Ikeda 1998	Not all patients were being retreated and unable to obtain information regarding data just for retreated ones.
Ikeda 2000	RCT including both naive and relapsers.
Imai 1997	Randomized trial of treatment‐naive patients only.
Iyoda 2000	Uncontrolled study.
Jensen 2009	Randomized trial comparing different regimens of peginterferon.
Kakumu 1994	Non‐randomized study.
Katayama 2001	Uncontrolled study.
Kishihara 1995	Non‐randomized trial.
Kumar 2001	RCT comparing different ribavirin plus interferon regimens.
Le 1996	Uncontrolled study.
Leroy 2001	RCT comparing different ribavirin plus interferon regimens.
Lindsay 1996	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Lodato 2005	RCT comparing different ribavirin plus interferon regimens.
Mangia 2005	RCT comparing different ribavirin and amantadine plus interferon regimens.
Mangia 2008	Trial compared interferon plus ribavirin.
Marcellin 1994	Uncontrolled study.
Marco 2000	RCT comparing different ribavirin plus interferon regimens.
Marriott 1992	Uncontrolled study.
Mathew 2006	RCT comparing different ribavirin plus interferon regimens.
Milella 1999	RCT comparing interferon versus interferon and ribavirin regimen.
Min 2001	RCT comparing different ribavirin plus interferon regimens.
Moreno‐Otero 2003	RCT comparing different ribavirin plus interferon regimens.
Mura 1999	RCT comparing interferon to no treatment, but not stated if patients treatment‐naive or previously treated or both; communication with Dr. Realdi indicated that records were not available so information could not be retrieved.
Neuman Manuela 2010	Different does of peg‐interferon compared; no untreated control group.
Nevens 2005	RCT comparing different ribavirin plus interferon regimens.
Nishiguchi 1995	Probably non‐randomized trial, did not necessarily include previously treated patients only, and subgroups could not be differentiated.
Nomura 2004	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Pardo 1994	Uncontrolled study.
Payen 1998	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Perasso 1999	Uncontrolled study.
Picciotto 1997	Non‐randomized study.
Planas 2002	Prior treatment was reason for exclusion
Pockros 2007	RCT of gamma‐interferon.
Pol 1999	RCT comparing interferon versus interferon and ribavirin regimen.
Portal 2003	RCT comparing different ribavirin plus interferon regimens.
Poynard 1999	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Poynard 2003	RCT comparing different ribavirin plus interferon regimens.
Puoti 2001	RCT comparing different ribavirin plus interferon regimens.
Qu 2012	Meta‐analysis of trials comparing interferon to no therapy and describing HCC outcome; not all trials in this meta‐analysis included retreated patients and one of the trials was probably not even randomized.
Reichard 1994	Observational study.
Rodriguez‐Torres 2011	Trial compares interferon lambda to interferon alfa in treatment naive individuals.
Rolachon 1997	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Romero‐Gomez 2012	Meta‐analysis of trials comparing interferon alfa2a to alfa2b; unclear if patients treatment naive or previously treated.
Rustgi 2005	RCT comparing different ribavirin plus interferon regimens.
Salmeron 1999	RCT comparing interferon versus interferon and ribavirin regimen.
Saracco 1994	Uncontrolled study.
Saracco 2001	RCT comparing different ribavirin plus interferon regimens.
Saracco 2002	RCT comparing different ribavirin plus interferon regimens.
Sarrazin 2007	RCT comparing different SCH 503034 plus interferon regimen.
Scotto 1996	RCT comparing interferon versus interferon and ribavirin regimen.
Scotto 1998	Previously included but moved because only RCTs comparing IFN to no treatment with clinical data now being considered.
Shiffman 2000	RCT comparing different ribavirin plus interferon regimens.
Singal 2010	Meta‐analysis.
Soza 2005	Trial of gamma interferon.
Sporea 2006	Quasi‐randomized trial comparing different ribavirin plus interferon regimens.
Steindl‐Munda 2003	RCT comparing different ribavirin plus interferon regimens.
Suzuki 2001	RCT including naive patients and patients who had received interferon previously.
Tassopoulos 2003	RCT comparing different ribavirin plus interferon regimens.
Toyota 2002	RCT comparing interferon versus interferon and ribavirin regimen.
Valla 1999	Randomized trial comparing interferon to no interferon, but unclear if patients previously treated or not; further information requested from Dr. Valla via email (dominique.valla@bjn.ap‐hop‐paris.fr) on 4/22/12. Received response on April 24, 2012 indicating that all of the patients in the trial were treatment‐naive, so trial excluded.
Wartelle 1997	Insufficient data for inclusion. The dose and duration of previous interferon therapy are not described.
Weiland 1993	Uncontrolled study.
Yao 1997	RCT comparing consensus interferon to alfa‐interferon; unclear if patients were previously treated or not.
Zeuzem 2000	Trial compared different regimens of interferon; no untreated control group.
Zeuzem 2005	RCT comparing different ribavirin plus interferon regimens.

RCT = randomized controlled trial.