Cox proportional hazards models showing the risk of career-limiting medical conditions with demographic and military characteristics, injury status, mental health problems and persistent postconcussive symptoms
| Variable | Model 1* aHR (95% CI) | Model 2† aHR (95% CI) | Model 3‡ aHR (95% CI) | Model 4§ aHR (95% CI) |
|---|---|---|---|---|
| Age | ||||
| ≤24 | – | 1.00 | 1.00 | 1.00 |
| 25–34 | 1.33 (1.07 to 1.66) | 1.25 (1.00 to 1.55) | 1.24 (0.996 to 1.55) | |
| 35–44 | 1.81 (1.37 to 2.39) | 1.63 (1.23 to 2.15) | 1.57 (1.19 to 2.07) | |
| ≥45 | 2.88 (2.10 to 3.97) | 2.62 (1.90 to 3.62) | 2.48 (1.80 to 3.43) | |
| Sex | ||||
| Male | – | 1.00 | 1.00 | 1.00 |
| Female | 1.43 (1.17 to 1.76) | 1.14 (0.93 to 1.39) | 1.13 (0.92 to 1.39) | |
| Rank | ||||
| Officer | – | 1.00 | 1.00 | 1.00 |
| Senior NCM | 1.79 (1.38 to 2.32) | 1.60 (1.23 to 2.07) | 1.54 (1.19 to 2.00) | |
| Junior NCM | 2.55 (2.01 to 3.25) | 2.18 (1.72 to 2.78) | 2.09 (1.65 to 2.66) | |
| Component | ||||
| Reserve Force | – | 1.00 | 1.00 | 1.00 |
| Regular Force | 2.43 (1.90 to 3.11) | 2.21 (1.73 to 2.84) | 2.19 (1.71 to 2.81) | |
| Element | – | |||
| Land | 1.00 | 1.00 | 1.00 | |
| Sea | 1.04 (0.80 to 1.35) | 1.00 (0.77 to 1.30) | 1.01 (0.78 to 1.31) | |
| Air | 1.00 (0.83 to 1.21) | 1.07 (0.88 to 1.29) | 1.05 (0.87 to 1.27) | |
| Years of service | – | |||
| ≤5 | 1.00 | 1.00 | 1.00 | |
| 6–14 | 1.24 (1.03 to 1.49) | 1.13 (0.93 to 1.35) | 1.09 (0.90 to 1.31) | |
| ≥15 | 1.86 (1.40 to 2.47) | 1.64 (1.24 to 2.17) | 1.58 (1.19 to 2.09) | |
| Number of previous deployments | – | |||
| 0 | 1.00 | 1.00 | 1.00 | |
| 1 or 2 | 0.90 (0.78 to 1.05) | 0.96 (0.83 to 1.11) | 0.96 (0.83 to 1.11) | |
| ≥3 | 0.84 (0.68 to 1.03) | 0.90 (0.73 to 1.12) | 0.91 (0.74 to 1.12) | |
| Duration of last deployment (days) | – | |||
| ≤180 | 1.00 | 1.00 | 1.00 | |
| >181 | 0.94 (0.79 to 1.12) | 0.96 (0.81 to 1.14) | 0.97 (0.82 to 1.16) | |
| Combat exposure¶ | – | |||
| 1st tertile | 1.00 | 1.00 | 1.00 | |
| 2nd tertile | 1.44 (1.20 to 1.72) | 1.25 (1.05 to 1.50) | 1.23 (1.03 to 1.47) | |
| 3rd tertile | 2.06 (1.69 to 2.51) | 1.52 (1.24 to 1.85) | 1.49 (1.22 to 1.82) | |
| Injury status | ||||
| Uninjured | 1.00 | 1.00 | 1.00 | 1.00 |
| Non-MTBI injury | 2.05 (1.78 to 2.35) | 1.78 (1.54 to 2.05) | 1.56 (1.35 to 1.81) | 1.42 (1.22 to 1.65) |
| MTBI injury | 3.17 (2.64 to 3.81) | 2.67 (2.20 to 3.25) | 1.83 (1.49 to 2.24) | 1.65 (1.35 to 2.03) |
| Any mental disorder** | – | – | ||
| No | 1.00 | 1.00 | ||
| Yes | 2.70 (2.28 to 3.21) | 2.55 (2.15 to 3.02) | ||
| 3 or more PCS | – | – | ||
| No | 1.00 | 1.00 | ||
| Yes | 2.05 (1.72 to 2.44) | 1.87 (1.57 to 2.23) | ||
| Severe back or joint pain | – | – | – | |
| No | 1.00 | |||
| Yes | 1.63 (1.42 to 1.87) | |||
*Model 1: unadjusted.
†Model 2: Model 1 adjusted for sociodemographic and military characteristics.
‡Model 3: Model 2 adjusted for mental disorders and PCS.
§Model 4: Model 3 adjusted for severe back or joint pain (based on PHQ-15).
¶The following item cut-off was used for the combat exposure tertile categories: <3 items (1st tertile), 3–10 items (2nd tertile), more than 10 items (3rd tertile).
**Any mental disorder defined as any of the following: major depression (PHQ-2), PTSD (2-item PCL) or panic disorder.
MTBI, mild traumatic brain injury; NCM, non-commissioned member; PCS, postconcussive symptoms.