Demographic and clinical characteristics of the study subjects according to the MRI scanner changes between the index and postindex periodsa
| Index Variables | Total Patients with RRMS (n = 590) | Patients with RRMS with MRI Scanner Changes (n = 309) | Patients with RRMS without MRI Scanner Changes (n = 281) | P Valueb |
|---|---|---|---|---|
| Age at index in yr (median) (IQR) | 42 (36; 49) | 41 (35; 48) | 44 (37; 51) | .007 |
| Women (No.) (%) | 464 (78.6) | 247 (79.9) | 217 (77.2) | .422 |
| Race/ethnicity (No.) (%) | ||||
| Caucasian/white | 494 (83.7) | 252 (81.6) | 242 (86.1) | .319 |
| Non-Caucasian | 63 (10.7) | 37 (12.0) | 26 (9.3) | |
| Unknown | 33 (5.6) | 20 (6.5) | 13 (4.6) | |
| Body mass index at index (median) (IQR) | 26.6 (23.2–30.6) | 26.5 (23.3–30.4) | 26.6 (23–30.9) | .895 |
| Disease duration in yr (median) (IQR) | 8 (4; 13) | 7 (4; 12) | 8 (4; 13) | .148 |
| Number with relapse in 2 yr before index (No.) (%) | 236 (40.0) | 143 (46.3) | 93 (33.1) | .003 |
| EDSS at index (median) (IQR) | 2.0 (1.0–3.0) | 2.0 (1.0–3.0) | 2.5 (1.5–3.5) | .002 |
| Use of DMT 2 yr before index (No.) (%) | ||||
| Teriflunomide | 5 (0.9) | 3 (1) | 2 (0.7) | .749 |
| Glatiramer acetate | 175 (30.8) | 87 (28.9) | 88 (32.8) | .310 |
| Interferon-β | 317 (55.7) | 175 (58.1) | 142 (53) | .217 |
| Alemtuzumab | 1 (0.2) | 1 (0.3) | 0 (0) | .345 |
| Dimethyl fumarate | 38 (6.7) | 21 (7) | 17 (6.3) | .763 |
| No DMT | 94 (15.9) | 46 (14.9) | 48 (17.1) | .467 |
Note:—EDSS indicates Expanded Disability Status Scale; IQR, interquartile range; DMT, disease-modifying treatment.
↵a MRI changes include hardware/software/coil/protocol differences between the index and postindex.
↵b P values represent group comparisons of patients with MS with and without MRI changes during the follow-up derived with the Student t, χ2, and Mann-Whitney rank sum tests as appropriate.