Suicide and all-cause mortality in Swedish deployed military veterans: A population-based matched cohort study.

Objective To investigate suicide and mortality risk
in deployed military veterans versus non-deployed
comparators who had gone through military conscription
testing.
Design Population-based matched cohort study.
Setting Sweden.
Participants Participants were identified from the Military
Service Conscription Register and deployment status from
the Swedish Military Information Personnel Register. Of
1.9million conscripts, 21 721 had deployed at some time
between 1990 and 2013 (deployed military veterans).
Non-deployed comparators were matched to deployed
military veterans in two ways: (1) by cognitive ability,
psychological assessment, mental health, body mass
index, sex, birth-year and conscription-year (carefully
matched), with further adjustment for exercise capacity
and suicide attempt history; and (2) by sex, birth-year and
conscription-year (age- and sex-matched).
Main outcome Suicide retrieved from the Swedish
National Patient and Causes of Death Register until 31
December 2013.
Results During a median follow-up of 12 years, 39 and
211 deaths by suicide occurred in deployed military
veterans (n=21 627) and carefully matched non-deployed
comparators (n=107 284), respectively (15 vs 16/100
000 person-years; adjusted HR (aHR) 1.07; 95%CI 0.75
to 1.52; p=0.72) and 329 in age- and sex-matched
non-deployed comparators (n=108 140; 25/100 000
person-years; aHR 0.59; 95%CI 0.42 to 0.82; p=0.002).
There were 284 and 1444 deaths by suicide or attempted
suicides in deployed military veterans and carefully
matched non-deployed comparators, respectively (109 vs
112; aHR 0.99; 95%CI 0.88 to 1.13; p=0.93) and 2061
in age- and sex-matched non-deployed comparators
(158; aHR 0.69; 95%CI 0.61 to 0.79; p<0.001). The
corresponding figures for all-cause mortality for carefully
matched non-deployed comparators were 159 and 820
(61 vs 63/100 000 person-years; aHR 0.97; 95%CI 0.82
to 1.15; p=0.71) and 1289 for age- and sex-matched nondeployed
comparators (98/100 000 person-years; aHR
0.62; 95%CI 0.52 to 0.73; p<0.001).
Conclusion Deployed military veterans had similar
suicide and mortality risk as non-deployed comparators
after accounting for psychological, psychiatric and physical
factors. Studies of mental health in deployed veterans
need to adjust for more factors than age and sex for
comparisons to be meaningful.