Table 1. Characteristics of the Study Cohort.
| Characteristic | No. (%) | Standardized mean differencea | |
|---|---|---|---|
| TBI history (n = 301 169) | No TBI history (n = 1 258 759) | ||
| Age at index date, y | |||
| 17-24 | 105 157 (34.9) | 354 645 (28.2) | 0.15 |
| 25-34 | 123 563 (41.0) | 474 689 (37.7) | 0.07 |
| 35-44 | 48 244 (16.0) | 238 370 (18.9) | −0.08 |
| 45-54 | 20 398 (6.8) | 153 261 (12.2) | −0.19 |
| 55-64 | 3455 (1.2) | 34 292 (2.7) | −0.11 |
| ≥65 | 352 (0.1) | 3502 (0.3) | −0.04 |
| Sex | 0.21 | ||
| Male | 265 217 (88.1) | 1 012 159 (80.4) | |
| Female | 35 898 (11.9) | 246 600 (19.6) | |
| Race and ethnicity | |||
| Asian/Pacific Islander | 23 789 (7.9) | 72 771 (5.8) | 0.08 |
| Hispanic Black | 1411 (0.5) | 6997 (0.6) | −0.01 |
| Hispanic | 29 184 (9.7) | 120 438 (9.6) | 0.004 |
| Native American | 6083 (2.0) | 20 669 (1.6) | 0.03 |
| Non-Hispanic | |||
| Black | 42 996 (14.3) | 224 996 (17.9) | −0.10 |
| White | 194 841 (64.7) | 789 136 (62.7) | 0.04 |
| Unknown | 2865 (1.0) | 23 752 (1.9) | −0.08 |
| Education | |||
| Less than high school | 4642 (1.5) | 17 576 (1.4) | 0.01 |
| High school | 229 522 (76.2) | 817 636 (65.0) | 0.25 |
| Some college | 33 960 (11.3) | 166 527 (13.2) | −0.06 |
| College graduate | 22 614 (7.5) | 154 619 (12.3) | −0.16 |
| Graduate school | 8631 (2.9) | 86 619 (6.9) | −0.19 |
| Unknown | 1794 (0.6) | 15 782 (1.3) | −0.07 |
| Service branch | |||
| Army | 176 663 (58.7) | 531 511 (42.2) | 0.33 |
| Air Force | 32 316 (10.7) | 274 165 (21.8) | −0.30 |
| Marines | 54 624 (18.1) | 180 255 (14.3) | 0.10 |
| Navy/Coast Guard | 37 419 (12.4) | 271 336 (21.6) | −0.25 |
| Other | 147 (0.1) | 1492 (0.1) | −0.02 |
| Component | |||
| Guard | 37 365 (12.4) | 132 574 (10.5) | 0.06 |
| Reserve | 102 389 (34.0) | 486 975 (38.7) | −0.10 |
| Active | 161 415 (53.6) | 639 240 (50.8) | 0.06 |
| Rank | |||
| Officer | 19 529 (6.5) | 177 001 (14.1) | −0.25 |
| Warrant | 2521 (0.8) | 15 859 (1.3) | −0.04 |
| Enlisted | 279 084 (92.7) | 1 065 761 (84.7) | 0.25 |
| Deployment history | |||
| +Combat and Deploy | 235 195 (78.1) | 783 481 (62.2) | 0.35 |
| +Combat/−Deploy | 8001 (2.7) | 68 697 (5.5) | −0.14 |
| −Combat/+Deploy | 12 413 (4.1) | 66 365 (5.3) | −0.05 |
| −Combat or Deploy | 45 560 (15.1) | 340 216 (27.0) | −0.29 |
| Smoking history | 173 318 (57.6) | 497 203 (39.5) | 0.37 |
| Substance use disorder | 47 616 (15.8) | 130 755 (10.4) | 0.16 |
| Obesity | 38 091 (12.7) | 157 393 (12.5) | 0.004 |
| Obstructive sleep apnea | 20 890 (6.9) | 68 519 (5.4) | 0.06 |
| Insomnia | 55 677 (18.5) | 98 978 (7.9) | 0.32 |
| PTSD | 82 543 (27.4) | 82 230 (6.5) | 0.58 |
| Depression | 74 704 (24.8) | 157 472 (12.5) | 0.32 |
| Anxiety | 60 558 (20.1) | 119 947 (9.5) | 0.30 |
| Hyperlipidemia | 37 598 (12.5) | 192 814 (15.3) | −0.08 |
| Kidney disease | 1047 (0.4) | 5282 (0.4) | −0.01 |
| Hypertension | 32 220 (10.7) | 142 694 (11.3) | −0.02 |
| Diabetes, types 1 and 2 | 4388 (1.5) | 25 481 (2.0) | −0.04 |
Abbreviations: PTSD, posttraumatic stress disorder; TBI, traumatic brain injury.
a
Standardized mean difference for 2 groups is defined as the difference in means (for a continuous variable) or proportions (1 category at a time for categorical variables) divided by pooled SD.