Table 2.
Odds ratios of the association between (a) any oral contraceptive pill exposure and subsequent multiple sclerosis, (b) combined oral contraceptive pill exposure and subsequent multiple sclerosis and (c) progesterone-only oral contraceptive exposure and subsequent multiple sclerosis.
| All | <2 years before diagnosis | 2-5 years before diagnosis | >5 years before diagnosis | |
|---|---|---|---|---|
| Any oral contraceptive pill exposure and subsequent multiple sclerosis | ||||
| Odds ratio (95% CI) for any OC from unadjusted model | 1.13 (0.95, 1.34) | 1.03 (0.70, 1.48) | 1.32 (0.97, 1.77) | 1.07 (0.86, 1.34) |
| Odds ratio (95% CI) for any OC from adjusted model a | 1.13 (0.94, 1.35) | 1.04 (0.70, 1.51) | 1.34 (0.98, 1.83) | 1.06 (0.84, 1.33) |
| Number of cases (% of N) | 891 (20.0%) | 715 (19.6%) | 739 (19.9%) | 793 (19.7%) |
| Number of cases with non-exposure (%) | 678 (76.1%) | 678 (94.8%) | 678 (91.7%) | 678 (85.5%) |
| Number of cases with OC exposure (%) | 213 (23.9%) | 37 (5.2%) | 61 (8.3%) | 115 (14.5%) |
| Number of controls (% of N) | 3564 (80.0%) | 2933 (80.4%) | 2976 (80.1%) | 3226 (80.3%) |
| Number of controls with non-exposure (%) | 2786 (78.2%) | 2786 (95.0%) | 2786 (93.6%) | 2786 (86.4%) |
| Number of controls with OC exposure (%) | 777 (21.8%) | 147 (5.0%) | 190 (6.4%) | 440 (13.6%) |
| Combined oral contraceptive pill exposure and subsequent multiple sclerosis | ||||
| Odds ratio (95% CI) for COCP from unadjusted model | 1.10 (0.91, 1.33) | 0.95 (0.59, 1.48) | 1.25 (0.85, 1.79) | 1.09 (0.85, 1.38) |
| Odds ratio (95% CI) for COCP from adjusted model a | 1.08 (0.88, 1.32) | 0.93 (0.57, 1.48) | 1.25 (0.84, 1.81) | 1.06 (0.83, 1.35) |
| Number of cases (% of N) | 891 (20.0%) | 757 (19.7%) | 773 (19.9%) | 829 (19.9%) |
| Number of cases with non-COCP (%) | 734 (82.4%) | 734 (97.0%) | 734 (95.0%) | 734 (88.5%) |
| Number of cases with COCP exposure (%) | 157 (17.6%) | 23 (3.0%) | 39 (5.0%) | 95 (11.5%) |
| Number of controls (% of N) | 3564 (80.0%) | 3081 (80.3%) | 3110 (80.1%) | 3337 (80.1%) |
| Number of controls with non-COCP (%) | 2983 (83.7%) | 2983 (96.8%) | 2983 (95.9%) | 2983 (89.4%) |
| Number of controls with COCP exposure (%) | 579 (16.2%) | 98 (3.2%) | 127 (4.1%) | 354 (10.6%) |
| Progesterone-only oral contraceptive exposure and subsequent multiple sclerosis | ||||
| Odds ratio (95% CI) for POP from unadjusted model | 1.12 (0.90, 1.39) | 1.35 (0.88, 2.02) | 1.19 (0.80, 1.72) | 0.98 (0.71, 1.33) |
| Odds ratio (95% CI) for POP from adjusted model a | 1.13 (0.90, 1.41) | 1.35 (0.87, 2.04) | 1.18 (0.79, 1.73) | 0.99 (0.71, 1.36) |
| Number of cases (% of N) | 891 (20.0%) | 804 (19.9%) | 809 (19.9%) | 824 (19.8%) |
| Number of cases with non-POP (%) | 773 (86.8%) | 773 (96.1%) | 773 (95.6%) | 773 (93.8%) |
| Number of cases with POP exposure (%) | 118 (13.2%) | 31 (3.9%) | 36 (4.4%) | 51 (6.2%) |
| Number of controls (% of N) | 3564 (80.0%) | 3230 (80.1%) | 3260 (80.1%) | 3348 (80.2%) |
| Number of controls with non-POP (%) | 3137 (88.0%) | 3137 (97.1%) | 3137 (96.2%) | 3137 (93.7%) |
| Number of controls with POP exposure (%) | 427 (12.0%) | 93 (2.9%) | 123 (3.8%) | 221 (6.3%) |
CI: confidence interval; OC: oral contraceptives; IMD: index of multiple deprivation; COCP: combined oral contraceptive pill; POP: progesterone-only pill.
a
Adjusted for age, ethnicity and IMD level.