Table 3.
Adjusted hazard ratios for firearm and non-firearm suicide among Millennium Cohort Study participants (n = 195,257).
| Firearm suicide (n = 308) |
Non-firearm suicide (n = 156) |
Comparison of suicide methods |
||||||
|---|---|---|---|---|---|---|---|---|
| HR | 95% CI | p | HR | 95% CI | p | χ2 | p | |
| Demographic factors | ||||||||
| Age (5-year increments) | 0.85 | (0.78, 0.94) | 0.0010 | 0.90 | (0.80, 1.01) | 0.085 | 0.47 | 0.494 |
| Sex (ref: Female) | 3.69 | (2.59, 5.24) | <0.0001 | 1.94 | (1.30, 2.90) | 0.0011 | 5.56 | 0.018 |
| Panel (Ref: Panel 1, 2001–2003) | <0.0001 | 0.436 | ||||||
| Panel 2 (2004–2006) | 0.86 | (0.58, 1.29) | 0.96 | (0.58, 1.59) | 0.11 | 0.738 | ||
| Panel 3 (2007–2008) | 1.88 | (1.32, 2.67) | 0.94 | (0.56, 1.56) | 4.88 | 0.027 | ||
| Panel 4 (2011–2013) | 2.19 | (1.50, 3.19) | 1.43 | (0.84, 2.43) | 1.63 | 0.201 | ||
| Military characteristics | ||||||||
| Service branch (Ref: Air Force) | 0.0037 | 0.546 | ||||||
| Army | 1.10 | (0.82, 1.46) | 1.28 | (0.83, 1.95) | 0.34 | 0.562 | ||
| Navy/Coast Guard | 0.52 | (0.34, 0.80) | 1.00 | (0.58, 1.71) | 3.52 | 0.061 | ||
| Marine Corps | 0.99 | (0.66, 1.47) | 1.00 | (0.53, 1.90) | 0.00 | 0.976 | ||
| Deployment/combat experience (Ref: Deployed, no combat) | 0.149 | 0.027 | ||||||
| Not deployed | 1.30 | (0.88, 1.93) | 2.61 | (1.28, 5.30) | 2.80 | 0.094 | ||
| Deployed, combat | 1.05 | (0.72, 1.53) | 2.04 | (1.00, 4.13) | 2.61 | 0.106 | ||
| Deployed, combat unknown | 2.00 | (0.89, 4.94) | 4.18 | (1.28, 13.62) | 1.02 | 0.312 | ||
| Health behaviors and psychosocial factors | ||||||||
| Smoking status (Ref: Never smoked) | <0.0001 | 0.0002 | ||||||
| Previously smoked | 1.66 | (1.25, 2.21) | 2.14 | (1.45, 3.17) | 1.07 | 0.301 | ||
| Currently smokes | 1.97 | (1.50, 2.60) | 2.04 | (1.36, 3.05) | 0.02 | 0.895 | ||
| Alcohol-related problemsa | 1.47 | (1.12, 1.93) | 0.0050 | 1.56 | (1.07, 2.27) | 0.019 | 0.06 | 0.806 |
| Life stressorsb | 1.35 | (1.05, 1.72) | 0.017 | 1.50 | (1.06, 2.12) | 0.022 | 0.25 | 0.615 |
| Physical health factors | ||||||||
| BMI (Ref: Normal weight) | 0.022 | 0.0091 | ||||||
| Overweight (25.0, −29.99 kg/m2) | 0.82 | (0.64, 1.04) | 0.60 | (0.42, 0.85) | 2.09 | 0.149 | ||
| Obese (>30.0 kg/m2) | 0.56 | (0.36, 0.87) | 0.60 | (0.34, 1.05) | 0.04 | 0.848 | ||
| Mental health factors | ||||||||
| Probable depression (PHQ-8)c | 1.97 | (1.36, 2.87) | 0.0004 | 0.78 | (0.44, 1.40) | 0.407 | 6.86 | 0.0088 |
| History of major depression diagnosis | 1.69 | (1.20, 2.37) | 0.0024 | 2.75 | (1.81, 4.18) | <0.0001 | 3.16 | 0.075 |
| History of bipolar diagnosis | 0.91 | (0.39, 2.12) | 0.831 | 3.40 | (1.76, 6.55) | 0.0003 | 5.81 | 0.016 |
PHQ, Patient Health Questionnaire.
Note. Variables were manually removed from the model until all variables had p < 0.05 in at least one suicide method model for comparison purposes. Model selection process dropped variables in the following order: Risky drinking, service component, paygrade, social support, multiple somatic symptoms, bodily pain, history of PTSD diagnosis, probable anxiety, education, race and ethnicity, marital status, sleep duration, and probable PTSD.
Endorsement of 1 or more item on the PHQ alcohol items.
Endorsed one of more of the following: disabling illness/injury, divorce/separation, major financial problems, violent assault, sexual harassment, sexual assault.
Assessed using the PHQ depression items.