Table 2. Factors in the MSSS Progression Slope During Secondary Progressive Multiple Sclerosisa.
| Variable | All patients (N = 1621) | Patients with superimposed relapse(s) (n = 661) | Patients with no relapse(s) during SPMS (n = 960) | |||
|---|---|---|---|---|---|---|
| β (95% CI) | P value | β (95% CI) | P value | β (95% CI) | P value | |
| Male sex | 0.024 (−0.004 to 0.053) | .09 | 0.012 (−0.026 to 0.051) | .52 | 0.035 (−0.007 to 0.077) | .10 |
| Age at MS onset, y | −0.001 (−0.002 to 0.000) | .11 | −0.003 (−0.005 to −0.001) | .003 | 0.001 (−0.001 to 0.003) | .42 |
| EDSS score/step at MS diagnosis | 0.001 (−0.009 to 0.012) | .75 | 0 (−0.015 to 0.014) | .97 | 0.003 (−0.012 to 0.018) | .68 |
| Relapse rate, No./y | ||||||
| Early RRMSb | 0.010 (−0.014 to 0.034) | .40 | 0.007 (−0.022 to 0.036) | .66 | 0.034 (−0.007 to 0.076) | .11 |
| SPMS | −0.029 (0.016 to 0.073) | .20 | 0.018 (−0.043 to 0.078) | .57 | NA | NA |
| Proportion of patients with early RRMS receiving DMT (per 25% increase) | ||||||
| Low efficacy | 0.006 (−0.004 to 0.016) | .26 | 0.006 (−0.007 to 0.020) | .35 | 0.004 (−0.012 to 0.019) | .64 |
| Medium efficacy | −0.046 (−0.104 to 0.013) | .12 | −0.115 (−0.213 to −0.017) | .02 | −0.015 (−0.089 to 0.059) | .68 |
| High efficacy | 0.008 (−0.025 to 0.041) | .64 | 0.028 (−0.020 to 0.076) | .25 | −0.019 (−0.066 to 0.028) | .43 |
| Proportion of patients with SPMS receiving DMT (per 25% increase) | ||||||
| Low efficacy | −0.015 (−0.025 to −0.005) | .003 | −0.025 (−0.039 to −0.012) | <.001 | −0.008 (−0.023 to 0.007) | .29 |
| Medium efficacy | −0.015 (−0.032 to 0.001) | .06 | −0.022 (−0.044 to 0.001) | .06 | −0.012 (−0.036 to 0.011) | .31 |
| High efficacy | −0.021 (−0.037 to −0.006) | .007 | −0.034 (−0.056 to −0.013) | .002 | −0.010 (−0.032 to 0.012) | .39 |
| Adjustment variables | ||||||
| Time from MS onset to diagnosis, y | 0.012 (0.009 to 0.015) | <.001 | 0.010 (0.007 to 0.015) | <.001 | 0.013 (0.009 to 0.016) | <.001 |
| Time from MS diagnosis to SPMS conversion, y | 0.013 (0.009 to 0.016) | <.001 | 0.011 (0.006 to 0.016) | <.001 | 0.014 (0.009 to 0.019) | <.001 |
| EDSS score/step at SPMS conversion | 0 (−0.015 to 0.014) | .99 | −0.003 (−0.023 to 0.017) | .77 | 0.001 (−0.020 to 0.024) | .86 |
| Follow-up duration during SPMS, y | 0.001 (−0.003 to 0.004) | .74 | −0.001 (−0.006 to 0.003) | .56 | 0.002 (−0.003 to 0.008) | .39 |
Abbreviations: DMT, disease-modifying therapy; EDSS, Expanded Disability Status Scale; MS, multiple sclerosis; MSSS, Multiple Sclerosis Severity Score; NA, not applicable; RRMS, relapsing-remitting multiple sclerosis; SPMS, secondary progressive multiple sclerosis.
a
Results of the multivariable linear mixed model for the entire cohort and 2 subgroups (dichotomized by the presence of any superimposed relapses during SPMS).
b
Early RRMS was defined as the first 4 years after MS diagnosis.