Baseline characteristics for cases and controls in analyses of tramadol and seizure
| Characteristic | (a) Primary analysis* | (b) Secondary analysis* | ||
| No (%) of patients† | No (%) of patients† | |||
| Cases (n=96 753) | Ctrls‡ (n=888 540) | Cases (n=20 507) | Ctrls‡ (n=204 531) | |
| Age (years) | ||||
| <18 | 28 648 (29.6) | 284 988 (32.1) | 7204 (35.1) | 72 024 (35.2) |
| 18–29 | 5791 (6.0) | 57 926 (6.5) | 1517 (7.4) | 15 133 (7.4) |
| 30–39 | 8060 (8.3) | 80 416 (9.1) | 1797 (8.8) | 17 931 (8.8) |
| 40–49 | 11 972 (12.4) | 119 667 (13.5) | 2556 (12.5) | 25 593 (12.5) |
| 50–59 | 15 250 (15.8) | 152 985 (17.2) | 2865 (14.0) | 28 691 (14.0) |
| 60–64 | 4373 (4.5) | 42 830 (4.8) | 766 (3.7) | 7607 (3.7) |
| ≥65 | 22 659 (23.4) | 149 728 (16.9) | 3802 (18.5) | 37 552 (18.4) |
| Sex | ||||
| Women | 48 468 (50.1) | 448 537 (50.5) | 9366 (45.7) | 93 367 (45.6) |
| Men | 48 285 (49.9) | 440 003 (49.5) | 11 141 (54.3) | 111 164 (54.4) |
| Diagnoses§ | ||||
| Stroke | 5106 (5.3) | 18 155 (2.0) | 901 (4.4) | 4034 (2.0) |
| Cerebrovascular disease¶ | 3836 (4.0) | 10 541 (1.2) | 702 (3.4) | 2211 (1.1) |
| Previous brain injury | 955 (1.0) | 3284 (0.4) | 207 (1.0) | 787 (0.4) |
| Hypoxaemia | 550 (0.6) | 2481 (0.3) | 100 (0.5) | 559 (0.3) |
| Infection | 4201 (4.3) | 29 730 (3.3) | 856 (4.2) | 7121 (3.5) |
| Alzheimer’s disease | 1180 (1.2) | 3237 (0.4) | 301 (1.5) | 765 (0.4) |
| Depression | 4960 (5.1) | 23 088 (2.6) | 1070 (5.2) | 4781 (2.3) |
| Anxiety | 3273 (3.4) | 16 117 (1.8) | 659 (3.2) | 3429 (1.7) |
| Head injury | 3938 (4.1) | 18 919 (2.1) | 911 (4.4) | 4633 (2.3) |
| Malnutrition | 356 (0.4) | 1088 (0.1) | 77 (0.4) | 168 (0.1) |
| Diabetes | 11 968 (12.4) | 72 603 (8.2) | 2267 (11.1) | 15 442 (7.5) |
| Cancer | 16 354 (16.9) | 122 709 (13.8) | 2862 (14.0) | 26 459 (12.9) |
| Hospitalisations§ | ||||
| None | 85 648 (88.5) | 838 310 (94.3) | 18 247 (89.0) | 193 405 (94.6) |
| One | 8747 (9.0) | 43 044 (4.8) | 1745 (8.5) | 9650 (4.7) |
| Two | 1750 (1.8) | 5791 (0.7) | 362 (1.8) | 1191 (0.6) |
| Three or more | 608 (0.6) | 1395 (0.2) | 153 (0.7) | 285 (0.1) |
| Drug utilisation§ | ||||
| No of drugs, median (IQR) | 4 (1,8) | 4 (1,6) | 4 (1,7) | 3 (1,6) |
| Bupropion | 1924 (2.0) | 10 535 (1.2) | 437 (2.1) | 2058 (1.0) |
| Other antidepressant | 14 320 (14.8) | 75 005 (8.4) | 2798 (13.6) | 15 522 (7.6) |
| Anticholinergics | 4794 (5.0) | 29 900 (3.4) | 830 (4.0) | 6663 (3.3) |
*The primary analysis used a sensitive definition of seizure, while the secondary analysis used a more specific definition of seizure.
†Except where indicated.
‡Ctrls=controls.
§In year prior to cohort entry.
¶Cerebrovascular disease other than stroke.