Characteristics of cases and controls
| Exposure | Relapsing-onset MS | Progressive-onset MS | Controls |
| N | 7520 | 540 | 11 386 |
| Females, n (%) | 5501 (73) | 321 (59) | 8278 (73) |
| Nordic | 6645 (88) | 490 (91) | 9974 (86) |
| Non-Nordic European | 501 (7) | 41 (8) | 875 (8) |
| Non-European | 374 (5) | 10 (2) | 767 (7) |
| Ever smoking, n (%) | 4108 (55) | 332 (61) | 5106 (45) |
| Current smoking, n (%) | 2670 (36) | 190 (35) | 2984 (26) |
| Past smoking, n (%) | 1438 (19) | 142 (26) | 2122 (19) |
| Cumulative dose of smoking, pack years (SD) | 7.6 (8.5) | 12.3 (11) | 7.2 (8.6) |
| Exclusive snuff users, n (%) | 316 (4.3) | 21 (4.0) | 604 (5.4) |
| No alcohol consumption, n (%) | 2009 (27) | 152 (28) | 3000 (26) |
| Low alcohol consumption, n (%) | 1438 (19) | 110 (20) | 2102 (18) |
| Moderate alcohol consumption, n (%) | 3156 (42) | 217 (40) | 4679 (41) |
| High alcohol consumption, n (%) | 917 (12) | 61 (11) | 1605 (14) |
| Normal weight, kg/m2 (SD) | 6200 (89) | 461 (86) | 9720 (89) |
| Overweight, n (%) | 772 (7.7) | 40 (11) | 969 (8.9) |
| Obesity, n (%) | 234 (3.1) | 16 (3.3) | 226 (2.1) |
| Mean sun exposure index (SD) | 6.1 (1.8) | 5.8 (1.7) | 6.4 (1.8) |
| Low sun exposure, n (%) | 1818 (25) | 156 (30) | 2127 (19) |
| Mean EBNA-1 antibody levels (SD) | 6821 (3079) | 6232 (3173) | 4894 (3245) |
| Median EBNA-1 antibody levels | 6838 | 6166 | 4915 |
| High EBNA-1 antibody levels | 3463 (78) | 280 (70) | 2718 (53) |
| DRB1*15:01 positive | 3411 (58) | 246 (56) | 1843 (28) |
| A*02:01 negative | 3371 (57) | 237 (54) | 2927 (45) |
| Age at disease onset (SD) | 32.9 (10.0) | 42.3 (11.0) |
EBNA-1, Epstein-Barr virus nuclear antigen-1; MS, multiple sclerosis.