Table 2.
PML Onset and Course
| S1P-RM (n = 20) | Natalizumab (n = 64) | p Value | |
| PML characteristics at onset | |||
| Presentation at PML onset, n (%) | 0.035a | ||
| Asymptomatic | 0 (0) | 6/31 (19.4) | |
| Acute | 6 (30) | 3/31 (9.7) | |
| Progressive | 14 (70) | 22/31 (71) | |
| Classification according to PML criteria, n (%) | <0.001a | ||
| Definite | 19 (95) | 30 (46.9) | |
| Probable | 0 (0) | 21 (32.8) | |
| Possible | 1 (5) | 13 (20.3) | |
| MRI characteristics at onset | |||
| Gd+ lesions (iPML), n (%) | 13 (65) | 25 (39.1) | 0.042a |
| Sub/supratentorial involvement, n (%) | 0.098a | ||
| Subtentorial | 3 (15) | 8 (12.5) | |
| Supratentorial | 11 (55) | 49 (76.6) | |
| Both | 6 (30) | 7 (10.9) | |
| Distribution of PML lesions, n (%) | 0.002a | ||
| Unilobar | 1 (5) | 21/63 (33.3) | |
| Multilobar | 3 (15) | 20/63 (31.7) | |
| Widespread | 16 (80) | 22/63 (34.9) | |
| JC virus load at PML onset | |||
| Copies/mL, median (IQR25-75) | 852 (106.5–4,923)c | 294 (29–3,000)d | 0.205b |
| JCV-negative patients, n (%) | 1 (5) | 2 (3.1) | 0.693a |
| Blood lymphocytes count at PML onset | |||
| Total, median (IQR25-75) | 365 (295–535)e | 3,875 (3,190–4,152.5)f | <0.001b |
| Time from PML first suspicion to diagnosis in days, median (IQR25-75) | 15.5 (3.3–88.5) | 26 (9.3–69.3) | 0.636b |
| PML course and treatment | |||
| Initial attitude | |||
| PML onset during immunosuppressive treatment, n (%) | 19 (95) | 58 (90.6) | 0.537a |
| Delay between PML onset and DMT interruption in days, median (IQR25-75) | 13 (2–42)g | 0 (0–14)h | 0.06b |
| Plasma exchanges, n (%) | 5 (25) | 51 (79.7) | <0.001a |
| Treatment at the acute phase | |||
| Corticosteroids, n (%) | 13 (65) | 52 (81.3) | 0.129a |
| Context in which corticosteroids were started, n (%) | < 0.001a | ||
| iPML/IRIS | 9 (69.2) | 47/47 (100) | |
| MS relapse | 2 (15.4) | 0/47 (0) | |
| Else | 2 (15.4) | 0/47 (0) | |
| Maraviroc, n (%) | 6 (30) | 13/63 (20.6) | 0.385a |
Abbreviations: iPML = inflammatory PML; IQR = interquartile range; IRIS = immune reconstitution inflammatory syndrome; NTZ = natalizumab; S1P-RM = sphingosine-1-phosphate receptor modulators.
a
Asymptotic Pearson χ2.
b
Student t test.
c
Three values are missing.
d
Five values are missing.
e
Two values are missing.
f
Fifty values are missing.
g
One value is missing.
h
Seven values are missing.