Table 2

Univariate regressions of the relationship between 2 year outcome measured in the original pivotal interferon β-1b study and the 16 year outcome for physical and cognitive function*

Physical outcome (logistic regression)Cognitive outcome (linear regression)
ORR2p ValueSlopeR2p Value
Baseline variables
 Baseline EDSS2.070.22<0.0001–1.120.12<0.0001
 MSSS at trial onset1.230.070.0004–0.250.020.09
 Baseline MRI T2 BOD (cm2)1.030.070.001–0.110.21<0.0001
 Duration of MS (y)1.070.050.003–0.150.050.004
 Third ventricular width (mm)1.180.040.011–0.940.21<0.0001
 Age at trial start1.030.01NS–0.190.00NS
 Age at MS onset0.980.01NS0.120.040.02
 Annual relapse rate prior to trial (2 years)1.110.00NS0.070.00NS
 Premorbid IQ0.990.00NS0.180.14<0.0001
 Gender0.910.00NS0.770.00NS
On-RCT variables
 Annual relapse rate1.820.12<0.0001–0.470.02NS
 Actual EDSS change—baseline to 2 years1.590.11<0.0001–0.320.01NS
 Categorical EDSS change (≥1 point)2.710.060.002–1.680.020.05
 Confirmed 1 point EDSS progression1.840.020.050.810.00NS
 Change, third ventricular width (mm)1.060.00NS–1.270.070.003
 50 μg treatment group during RCT0.740.01NS1.420.020.09
 250 μg treatment group during RCT1.070.01NS1.410.020.09
 Total IFNβ-1b exposure (years) (on LTF)0.980.00NS–0.080.01NS
 No of new T2 lesions0.960.01NS–0.100.01NS
 NAbs (≥20 NU/ml)0.830.00NS–0.490.00NS
 Change, MRI T2 BOD (cm2)1.010.00NS–0.010.01NS
  • * Physical outcome=either SPMS or EDSS=6; cognitive outcome=Cognitive Performance Index (see text).

  • NS=p>0.1.

  • Comparison versus placebo.

  • BOD, burden of disease; EDSS, Expanded Disability Status Scale score; IFNβ, interferon β; MS, multiple sclerosis; MSSS, Multiple Sclerosis Severity Score; NAbs, neutralising antibodies; RCT, randomised controlled trial; SPMS, secondary progressive multiple sclerosis.