Table 1.
Demographic Characteristics and Illness History of the Participants at Randomization, According to Prespecified Subgroups and Trial Group.*
| Characteristic | Aspirin (N=9525) |
Placebo (N = 9589) |
|---|---|---|
| Age — no. (%)† | ||
| 65–73 yr | 4719 (49.5) | 4823 (50.3) |
| ≥74 yr | 4806 (50.5) | 4766 (49.7) |
| Female sex — no. (%) | 5373 (56.4) | 5410 (56.4) |
| Country — no. (%) | ||
| Australia | 8322 (87.4) | 8381 (87.4) |
| United States | 1203 (12.6) | 1208 (12.6) |
| Race or ethnic group — no.(%)‡ | ||
| White | ||
| Australia | 8169 (85.8) | 8193 (85.4) |
| United States | 539 (5.7) | 549 (5.7) |
| Black | 451 (4.7) | 450 (4.7) |
| Hispanic | 240 (2.5) | 248 (2.6) |
| Other | 126 (1.3) | 149 (1.6) |
| Body-mass index§ | 28.1±4.8 | 28.1±4.7 |
| Current smoking — no. (%) | 352 (3.7) | 383 (4.0) |
| Diabetes mellitus — no. (%)¶ | 1027 (10.8) | 1030 (10.7) |
| Hypertension — no. (%)∥ | 7065 (74.2) | 7148 (74.5) |
| Dyslipidemia — no. (%)** | 6159 (64.7) | 6308 (65.8) |
| Personal history of cancer — no. (%) | 1827 (19.2) | 1833 (19.1) |
| Previous regular aspirin use — no. (%)†† | 1053 (11.1) | 1041 (10.9) |
| Frailty — no. (%)‡‡ | ||
| Not frail | 5603 (58.8) | 5643 (58.8) |
| Prefrail | 3707 (38.9) | 3740 (39.0) |
| Frail | 215 (2.3) | 206 (2.1) |
Plus-minus values are means ±SD. There were no significant (P>0.05) differences between the two trial groups; all differences were less than 0.25 SD (if means were compared), and odds ratios were between 0.67 and 1.50 (if proportions were compared).
The subgroups for age were based on the median age of the participants overall (74 years).
Race and ethnic group were reported by the participants. Other race or ethnic group was defined as any category with less than 200 participants overall, which included Aboriginal or Torres Strait Islander (12 participants), Native American (6), multiple races or ethnic groups (64), Native Hawaiian or Pacific Islander (11), and those who indicated that they were not Hispanic but did not state another race or ethnic group (18).
The body-mass index is the weight in kilograms divided by the square of the height in meters.
The presence of diabetes was based on participants’ report of diabetes mellitus or a fasting glucose level of at least 126 mg per deciliter (≥7 mmol per liter) or receipt of treatment for diabetes.
Hypertension was defined by the receipt of treatment for high blood pressure or a blood pressure of more than 140/90 mm Hg at trial entry.
Dyslipidemia was defined by the receipt of cholesterol-lowering medication or as a serum cholesterol level of at least 212 mg per deciliter (≥5.5 mmol per liter) in Australia and at least 240 mg per deciliter (≥6.2 mmol per liter) in the United States or as a low-density lipoprotein level of more than 160 mg per deciliter (>4.1 mmol per liter).13,21
Previous regular aspirin use was defined according to participant-reported regular use of aspirin immediately before the first baseline visit, with a 1-month washout period before randomization.
Frailty was categorized on the basis of the adapted Fried frailty criteria, which included body weight, strength, exhaustion, walking speed, and physical activity (see the Supplementary Appendix).21 The category of prefrail included participants who met one or two criteria, and the category of frail included those who met three or more criteria.