Table 1

Characteristics of the trials included

Study, publication year, countries (No of centres)	Interventions	No of randomised patients	Inclusion criteria	Accrual period	Follow-up duration (months)	Sponsor
European SG,18 1998, Europe (32)	IFNβ-1b (Betaferon) 250 μg subcutaneously every other day	360	Age 18–55 years, EDSS 3.0–6.5 SPMS defined as deterioration independent of relapses, sustained for at least 6 months, following initial RR course, with or without superimposed exacerbations, with either at least two relapses or at least 1 point increase in EDSS over previous 2 years	September 1994–March 1998	36	Schering AG, Berlin, Germany
European SG,18 1998, Europe (32)	Placebo	358		September 1994–March 1998	36	Schering AG, Berlin, Germany
SPECTRIMS,19 2001, Europe, Canada and Australia (22)	IFNβ-1a (Rebif) 22 μg subcutaneously 3 times/week	209	Age 18–55 years; EDSS 3.0–6.5; pyramidal function score of at least 2. SPMS defined as deterioration for at least 6 months, following initial RR course, with or without superimposed exacerbations, with at least 1 point increase in EDSS over previous 2 years (or 0.5 points between EDSS score of 6.0 and 6.5)	Not reported	36	Serono International SA, Geneva, Switzerland
	IFNβ1a (Rebif) 44 μg subcutaneously, 3 times/week	204
	Placebo	205
IMPACT,20 2002, US (31), Canada (4), Europe (7)	IFNβ-1a (Avonex) 60 μg intramuscular injections weekly	217	Age 18–60 years, EDSS score 3.0–6.5 SPMS defined as deterioration over previous year; with or without superimposed exacerbations	March 1998–September 1998	24	Biogen Idec, Inc., Cambridge, MA, USA,
IMPACT,20 2002, US (31), Canada (4), Europe (7)	Placebo	219		March 1998–September 1998	24	Biogen Idec, Inc., Cambridge, MA, USA,
Nordic,21 2004, Denmark (4), Finland (6), Norway (12), Sweden (10)	IFNβ-1a (Rebif) 22 μg subcutaneously weekly	188	Age 18–65 years, EDSS <7.0 SPMS defined as deterioration for at least 6 months, following initial RR course, with or without superimposed exacerbations, with at least 1 point increase in EDSS over previous 4 years	Not reported	36	Serono International SA, Geneva, Switzerland
	Placebo	183		Not reported	36	Serono International SA, Geneva, Switzerland
North America SG,22 2004, USA (31), Canada (4)	IFNβ-1b (Betaferon) 250 μg subcutaneously every other day	317	Age 18–65 years, EDSS 3.0–6.5 History of MS of at least 2 years' duration. SPMS defined as deterioration sustained for at least 6 months, following at least one relapse, with at least 1 point increase in EDSS over previous 2 years.	August 1995–August 1999	36	Berlex Laboratories, Montville, NJ, USA
	IFNβ-1b (Betaferon) 160 μg/m² body surface area (mean administered dose 220 μg) every other day	314
	Placebo	308

EDSS, Expanded Disability Status Scale; IFNβ, interferon β; RR, relapsing remitting; SPMS, secondary progressive multiple sclerosis.