Low vitamin D level is associated with higher relapse rate in natalizumab treated MS patients

BackgroundPrevious research suggested a relationship between low vitamin D and relapse rate. We examined whether vitamin D levels were associated with: 1) MS severity and 2) recent MS relapse activity, in patients treated with natalizumab.MethodsAll patients (n = 118) were treated with natalizumab and were tested for vitamin D levels during the winter of 2009–10. Number of relapses during treatment with natalizumab was determined by retrospective chart review. MS severity was estimated with the Roxburgh's MS Severity Score (MSSS) at the time of the initial blood draw and 1 year preceding and following initial draws. Vitamin D levels of 50 nmol/L or greater were defined as normal.ResultsPatients with deficient vitamin D levels (DVD) totaled 45. Sixteen of the 26 patients with relapse in the year prior to the initial blood draw (4 patients had multiple relapses — all were in DVD) and 12 of 17 patients with relapse in the following year were in the DVD group. There was a significant difference between the normal vitamin D group (NVD) and DVD in MS relapse activity in the year prior (p = 0.005) and following blood draw (p = 0.006). There was no significant between group differences in MSSS at any time.ConclusionsNatalizumab treated patients with DVD were more likely to experience relapse and may experience more relapses than patients with NVD.