JAMA 2013;310(5):496-506
A cohort study published in JAMA tried to
answer the question what are the risk factors for suicide in the US military.
This is a hot topic as the rate of suicide has increased in US military
personnel from about 11/100,000 people in 2005 to about 18/100,000 so that now
deaths from suicide outnumber deaths from combat.
What the authors did was to gather together
three cohorts in 2000, 2003 and 2006. Importantly they included reservists as
well as full time members of the military (reservists make up about 30% of the
US army which is relatively high compared to other countries). Participants
were asked to complete a baseline questionnaire and then a questionnaire every
three years. About a third of people approached agreed to take part in the
study and they were more likely to be women, younger and college educated than
the typical US military population.
Death, the main outcome, was assessed from
the National Death Index and the Department of Defense Medical Mortality
Registry. The authors were particularly interested in whether deployment and
combat experience were linked to suicide, having gathered information about
this from records and surveys. The
questionnaires completed by the participants assessed various other factors
such as stressful life events; post-traumatic stress disorder; depression and
drinking (although they didn’t ask about other drug use which seems a
significant omission).
What they found in the 151,000 participants
is that 83 people died as a result of suicide between 2001 and 2008 which gives
a crude rate of 11.73 (95% confidence interval 9.21-14.26) per 100,000. What is
more important is not the crude rate (as the authors didn’t set out to
establish what the “true” rate was in the US military) but the risk factors
associated with suicides. They found that suicide was highest in those with
bipolar disorder, depression and alcohol problems. There was no link with
deployment or combat exposure – in fact those who were not deployed had higher crude
rates of suicide than those deployed once.
One way of expressing risk is to report the
population attributable risk which tells you how much the rate of a disorder
would reduce if you got rid of the risk factor.
(This is useful as it takes into account how common the risk factor is and how much it increases the risk – if
a risk factor is rare then from a population perspective how much it increases
your risk is relatively unimportant). In
this study the population attributable risk for alcohol related problems was
18%, depression 11% and bipolar disorder 5%.
So in this population, as in most risk
factor studies, it was the usual suspects of depression and substance use that
was associated with suicide. There are some caveats here though. In this study
there were only 83 suicides so there were wide confidence interval intervals in
the hazard ratios. There is also the possibility of the healthy deployment
issue – those personnel who were unwell or had substance abuse problems may
have been less likely to have been deployed or see combat. The study also only covers only 2005 to 2008
when the increase in suicides was beginning. It will be interesting to see if
later data supports these initial conclusions.
However, the study does beg the question of
whether there was something “depressogenic” about being in the US military. The
population of the US military is generally younger than other high income
country armies and deployment when it occurs is longer than other countries
with shorter breaks “at home”. Personal testimony from serving and recently
retired soldiers also contributes to a view that invading and occupying small
defenceless countries far away from the US can affect morale. However, this
argument also applies to armies from other countries such as Canada and the UK
where there has not been such an increase in military suicides.
Another argument to explain these findings
is that the response to mental illness in the military is problematic. We know
from the civilian population that identifying and responding to depression in
primary care is one of the best ways of reducing suicides. As the authors note
mental health problems in the military increase risk of suicide – just as in
civilian life- but the response is often different with a much greater
reluctance to divulge mental health problems.
This might explain why alcohol abuse – often used to self-medicate
psychiatric disorders - was the most important risk factor in this study.
No comments:
Post a Comment