Table 2. Characteristics of Black U.S. Army Soldiers Tested for Sickle Cell Trait Who Were on Active Duty between January 2011 and December 2014*.
| Characteristic | Sickle Cell Trait (N = 3564) | No Sickle Cell Trait (N = 44,380) |
|---|---|---|
| Male sex — no. (%) | 2488 (69.8) | 31,822 (71.7) |
| Age — yr | 30.7±7.8 | 30.5±7.6 |
| Military pay-grade category — no. (%) | ||
| Private, E1–E3 | 529 (14.8) | 6,238 (14.1) |
| Specialist or corporal, E4 | 1121 (31.5) | 13,389 (30.2) |
| Junior sergeant, E5–E6 | 1132 (31.8) | 14,039 (31.6) |
| Senior sergeant, E7–E9 | 424 (11.9) | 5,433 (12.2) |
| Warrant officer, W1–W5 | 73 (2.0) | 1,071 (2.4) |
| Junior officer, O1–O3 | 176 (4.9) | 2,896 (6.5) |
| Senior officer, O4–O10 | 109 (3.1) | 1,314 (3.0) |
| Health-related factors | ||
| BMI | 26.8±3.8 | 26.8±3.7 |
| APFT score ≥270 — no. (%)† | 620 (17.4) | 9,333 (21.0) |
| Tobacco use in previous 6 mo — no. (%) | 788 (22.1) | 9,909 (22.3) |
| Prescription medication in previous 2 mo — no. (%) | ||
| Statin | 43 (1.2) | 569 (1.3) |
| Antipsychotic agent | 29 (0.8) | 442 (1.0) |
| Stimulant | 9 (0.3) | 189 (0.4) |
| Exertional rhabdomyolysis — no. (%) | 42 (1.2) | 349 (0.8) |
| Death — no. (%) | ||
| Any cause | 7 (0.2) | 89 (0.2) |
| Battle-related | 1 (<0.1) | 13 (<0.1) |
| Non–battle-related | 6 (0.2) | 76 (0.2) |
*
Plus–minus values are means ±SD. The body-mass index (BMI) is the weight in kilograms divided by the square of the height in meters. All values that could vary over time were the values that were known for each participant in the last observed month before data censoring.
†
Scores on the Army Physical Fitness Test (APFT) range from 0 to 300, with higher scores indicating better physical performance. A minimum score of 180 is ordinarily required to pass. Soldiers who have a score of 90 or greater in each of the three fitness categories (push-ups, sit-ups, and cardiovascular endurance) are awarded recognition for high fitness.25