Table 2.
Association between different types of smoking and primary progressive multiple sclerosis (PPMS)
| Variables | Control group [n (%)] | PPMS group [n (%)] | Adjusted OR * (95% CI), P | Adjusted OR ** (95% CI), P | |
|---|---|---|---|---|---|
| Waterpipe smoking | Never | 233 (79.3) | 126 (86.3) | 1 | 1 |
| Ever | 61 (20.7) | 20 (13.7) | 1.29 (0.68-2.43), 0.427 | 1.19 (0.62-2.26), 0.588 | |
| Current | 21 (7.2) | 3 (2.0) | 0.48 (0.12-1.90), 0.300 | 0.49 (0.12-1.87), 0.298 | |
| Past | 38 (13.0) | 17 (11.6) | 2.01 (0.98-4.10), 0.055 | 1.83 (0.89-3.77), 0.096 | |
| Waterpipe smoking, duration (year) |
Never | 233 (79.8) | 126 (86.3) | 1 | 1 |
| ≤ 10 | 40 (13.7) | 14 (9.6) | 1.76 (0.83-3.73), 0.138 | 1.55 (0.72-3.32), 0.255 | |
| > 10 | 19 (6.5) | 6 (4.1) | 0.92 (0.32-2.66), 0.879 | 0.95 (0.33-2.74), 0.926 | |
| Waterpipe smoking, cumulative amount (pipes), min per week |
Never | 233 (82.3) | 126 (90.0) | 1 | 1 |
| ≤ 60 | 35 (12.4) | 8 (5.7) | 0.81 (0.34-1.95), 0.647 | 0.75 (0.31-1.82), 0.529 | |
| > 60 | 15 (5.3) | 6 (4.3) | 1.78 (0.58-5.40), 0.305 | 1.46 (0.48-4.40), 0.502 | |
| Cigarette smoking | Never | 241 (82.0) | 97 (66.4) | 1 | 1 |
| Ever | 53 (18.0) | 49 (33.6) | 2.54 (1.48-4.37), 0.001 | 2.48 (1.44-4.27), 0.001 | |
| Current | 35 (11.9) | 24 (16.4) | 2.03 (1.02-4.06), 0.044 | 1.98 (0.98-3.97), 0.055 | |
| Past | 18 (6.1) | 25 (17.1) | 3.33 (1.58-7.03), 0.002 | 3.23 (1.54-6.79), 0.002 | |
| Cigarette smoking, duration (year) |
Never | 241 (82.0) | 97 (67.4) | 1 | 1 |
| ≤ 15 | 35 (11.9) | 20 (13.9) | 2.43 (1.21-4.87), 0.012 | 2.43 (1.21-4.86), 0,012 | |
| > 15 | 18 (6.1) | 27 (18.7) | 2.48 (1.16-5.28), 0.018 | 2.36 (1.11-5.03), 0.026 | |
| Cigarette smoking, cumulative amount (total pack-years) |
Never | 241 (82.0) | 97 (69.3) | 1 | 1 |
| ≤ 120 | 38 (13.0) | 21 (15.0) | 1.36 (0.67-2.75), 0.392 | 1.35 (0.66-2.72), 0.403 | |
| > 120 | 14 (4.8) | 22 (15.7) | 4.86 (2.12-11.2), 0.001 | 4.81 (2.09-11.07), 0.001 | |
| Passive smoking | Never | 143 (48.6) | 43 (29.4) | 1 | 1 |
| Ever | 151 (51.4) | 103 (70.6) | 2.03 (1.25-3.31), 0.004 | 2.20 (1.34-3.62), 0.002 | |
| Passive smoking, duration (year) |
Never | 143 (55.9) | 43 (34.7) | 1 | 1 |
| ≤ 10 | 22 (8.6) | 6 (4.8) | 0.74 (0.25-2.15), 0.582 | 0.75 (0.25-2.22), 0.615 | |
| 11-20 | 38 (14.8) | 26 (21.0) | 2.22 (1.10-4.49), 0.025 | 2.50 (1.22-5.10), 0.012 | |
| > 20 | 53 (20.7) | 49 (39.5) | 2.73 (1.49-5.01), 0.001 | 2.87 (1.56-5.30), 0.001 | |
| Passive smoking (age of exposure) |
Never | 175 (60.3) | 63 (43.1) | 1 | 1 |
| ≤ 19 years | 44 (15.2) | 20 (13.7) | 1.14 (0.56-2.32), 0.701 | 1.29 (0.63-2.66), 0.473 | |
| ≥ 20 years | 21 (7.2) | 9 (6.2) | 0.74 (0.29-1.88), 0.530 | 0.82 (0.32-2.09), 0.680 | |
| Throughout life | 50 (17.3) | 54 (37.0) | 2.96 (1.67-5.24), 0.001 | 3.01 (1.69-5.34), 0.001 | |
| Mother’s smoking in the perinatal period |
No | 284 (96.6) | 144 (98.6) | 1 | 1 |
| Yes | 10 (3.4) | 2 (1.4) | 0.31 (0.05-1.76), 0.190 | 0.35 (0.05-2.13), 0.258 | |
OR: Odds ratio; CI: Confidence interval; PPMS: Primary progressive multiple sclerosis
*
Adjusted for age,
**
Adjusted for age and Socioeconomic status (SES)