Table 2.
Baseline characteristics of cases of acute myocardial infarction and matched controls*. Values are numbers (percentages) unless stated otherwise
| Characteristics | Cases (n=2229) | Controls (n=11 010) | Standardised difference† |
|---|---|---|---|
| Demographics | |||
| Mean (95% CI) age at index date | 80.6 (80.3 to 80.9) | 80.5 (80.4 to 80.7) | 0.01 |
| Male sex | 1129 (50.7) | 5578 (50.7) | 0 |
| Fifth of income: | |||
| Missing | 13 (0.6) | 49 (0.4) | 0.03 |
| 1 | 505 (22.7) | 2066 (18.8) | 0.1 |
| 2 | 445 (20.0) | 2282 (20.7) | 0.01 |
| 3 | 443 (19.9) | 2181 (19.8) | 0 |
| 4 | 442 (19.8) | 2241 (20.4) | 0.02 |
| 5 | 381 (17.1) | 2191 (19.9) | 0.07 |
| Rural residence | 401 (18.0) | 1584 (14.4) | 0.1 |
| Comorbidities | |||
| Mean (SD) No of unique drugs prescribed in previous year | 17.1 (8.5) | 12.1 (7.3) | 0.64 |
| Atrial fibrillation | 740 (33.2) | 2021 (18.4) | 0.37 |
| Coronary artery bypass grafting surgery | 61 (2.7) | 314 (2.9) | 0.01 |
| Cancer | 183 (8.2) | 613 (5.6) | 0.11 |
| Chronic renal insufficiency | 340 (15.3) | 418 (3.8) | 0.5 |
| Diabetes | 1098 (49.3) | 5374 (48.8) | 0.01 |
| Drugs used in previous year | |||
| Angiotensin converting enzyme inhibitors | 1284 (57.6) | 4571 (41.5) | 0.33 |
| Angiotensin receptor blockers | 616 (27.6) | 2584 (23.5) | 0.1 |
| Hydroxymethyl glutaryl coenzyme A reductase inhibitors (statins) | 1616 (72.5) | 5860 (53.2) | 0.39 |
| Clopidogrel | 832 (37.3) | 786 (7.1) | 0.98 |
| Warfarin | 397 (17.8) | 1403 (12.7) | 0.15 |
| Acetylsalicylic acid/dipyridamole | 52 (2.3) | 222 (2.0) | 0.02 |
| Hormone replacement therapy | 16 (0.7) | 82 (0.7) | 0 |
| Low molecular weight heparin | 28 (1.3) | 114 (1.0) | 0.02 |
| Diuretics | 1347 (60.4) | 5106 (46.4) | 0.28 |
| Diuretics, potassium sparing | 230 (10.3) | 784 (7.1) | 0.12 |
| Calcium channel blocker | 1090 (48.9) | 4104 (37.3) | 0.24 |
| History of outcome | |||
| Acute myocardial infarction | 181 (8.1) | 773 (7.0) | 0.04 |
All cells with values of 5 or less are reported as ≤5 for privacy reasons.
*Up to 5 controls were matched to each case on age (±1 year), sex, diabetes, and history of outcome.
†Difference between cases and controls divided by pooled standard deviation of two groups; standardised differences <0.1 indicate good balance between groups.