Table 1.
Characteristics of study participants (cases and controls) enrolled in the Environmental risk factors In MS (EnvIMS) Study
| Participant characteristics | Cases (n = 2251) | Controls (n = 4028) |
|---|---|---|
| Country of residence, % (n) | ||
| Canada | 26.1 (587) | 24.3 (978) |
| Italy | 31.4 (707) | 33.1 (1333) |
| Norway | 42.5 (957) | 42.6 (1717) |
| Age at study (years), mean (SD, range) | 41.9 (10.7, 18–80) | 44.4 (11.5, 18–86) |
| MS disease duration (years) mean (SD, range) | 6.5 (2.8, 0–11) | n/a |
| Sex, % female (n) | 69.4 (1563) | 70.3 (2832) |
| Ethnicity (Canada and Norway only), % (n) | ||
| At least one parent is European | 94.0 (1451) | 93.0 (2507) |
| Both parents non-European | 3.2 (50) | 4.9 (132) |
| Missing | 2.8 (43) | 2.1 (56) |
| Participant education, % (n) | ||
| Less than high school | 12.0 (271) | 8.9 (357) |
| Completed high school | 29.5 (663) | 27.0 (1088) |
| Post-secondary education | 51.4 (1158) | 54.5 (2195) |
| Missing | 7.1 (159) | 9.6 (388) |
| Highest level of education of parents, % (n) | ||
| Less than high school | 52.1 (1172) | 54.5 (2195) |
| Completed high school | 19.1 (429) | 18.7 (755) |
| Post-secondary education | 20.0 (451) | 17.4 (700) |
| Missing | 8.8 (199) | 9.4 (378) |
| Number of siblings, % (n) | ||
| Only child | 5.0 (203) | 6.4 (143) |
| 1 | 28.3 (1139) | 30.0 (675) |
| 2 | 27.5 (1109) | 29.0 (652) |
| 3 | 16.4 (662) | 15.7 (353) |
| 4 | 8.8 (353) | 7.7 (173) |
| 5 | 5.1 (206) | 3.6 (80) |
| 6+ | 8.0 (324) | 6.1 (138) |
| Missing | 1.6 (37) | 0.8 (32) |
| Physical activity age 13–19 years, % (n) | ||
| Light and heavy physical activity | 84.3 (1897) | 85.3 (3441) |
| Light physical activity only | 8.4 (189) | 7.4 (296) |
| No physical activity | 2.8 (63) | 2.6 (103) |
| Missing | 4.5 (102) | 4.7 (188) |
| Mother smoked during childhood, % (n) | ||
| Yes | 44.6 (1004) | 41.2 (1660) |
| No | 52.2 (1175) | 56.3 (2266) |
| Missing | 3.2 (72) | 2.5 (102) |
| Father smoked during childhood, % (n) | ||
| Yes | 59.6 (1342) | 59.2 (2386) |
| No | 36.8 (829) | 37.9 (1525) |
| Missing | 3.6 (80) | 2.9 (117) |
| Body shape at age 5 years | ||
| Mean (SD, range) | 2.4 (1.5, 1–9) | 2.3 (1.5, 1–8) |
| Missing, % (n) | 7.3 (164) | 7, 1 (287) |
| Body shape at age 10 years | ||
| Mean (SD, range) | 2.6 (1.5, 1–9) | 2.4 (1.5, 1–9) |
| Missing, % (n) | 7.0 (158) | 6.5 (262) |
| Body shape at age 15 years | ||
| Mean (SD, range) | 2.9 (1.4, 1–9) | 2.7 (1.4, 1–8) |
| Missing, % (n) | 6.3 (142) | 6.0 (242) |
| Mononucleosis infection before age 15 years, % (n) | ||
| 0–5 years | 0.4 (10) | 0.2 (7) |
| 6–10 years | 1.4 (31) | 0.6 (25) |
| 11–15 years | 5.4 (121) | 2.2 (90) |
| Outdoor allergies before age 15 years, % (n) | ||
| 0–5 years | 2.2 (49) | 2.0 (79) |
| 6–10 years | 5.3 (119) | 4.6 (185) |
| 11–15 years | 8.3 (186) | 7.0 (280) |
| Indoor allergies before age 15 years, % (n) | ||
| 0–5 years | 1.9 (43) | 1.6 (64) |
| 6–10 years | 4.0 (89) | 3.3 (131) |
| 11–15 years | 5.5 (124) | 4.8 (192) |
| Autoimmune disease before age 15 years (not including MS), % (n) | ||
| 0–5 years | 1.0 (22) | 0.7 (27) |
| 6–10 years | 1.5 (34) | 1.3 (54) |
| 11–15 years | 2.0 (45) | 1.8 (74) |