Combat Hazards Include New-Onset CHD in US Military

March 19, 2014

SAN DIEGO, CA — Participating in combat during wartime, more familiarly associated with posttraumatic stress disorder (PTSD), can independently raise the risk of new coronary heart disease (CHD), suggests a study of US military men and women deployed in Iraq and Afghanistan from 2001 to 2008[1]. The finding applied to new CHD whether self-diagnosed or formally diagnosed by a physician.

But a diagnosis of PTSD didn't by itself necessarily predict new CHD in the analysis, which instead suggests that PTSD may be part of a mechanism by which combat raises the risk, according to the authors, led by Dr Nancy F Crum-Cianflone (Naval Health Research Center, San Diego, CA).

"These findings suggest that young military personnel who experienced combat during the recent conflicts may have a heightened risk for the development of CHD," the group writes, noting also that new cases of CHD among personnel in active service and veterans were "uncommon," at a rate of about 1%.

The group prospectively looked at 60 025 current and former members of all US service branches, participants in the Millennium Cohort Study , from 2001 to 2008 for self-reported cases of new CHD; they also looked at a subgroup of 23 794 on active service with International Classification of Diseases (ICD) codes indicating CHD in their electronic medical records.

New CHD was self-reported by 627 members of the overall cohort over a mean follow-up of 5.6 years. Among personnel deployed to Iraq and Afghanistan, those who experienced combat, compared with those who didn't, had a fully adjusted (including for PTSD) odds ratio (OR) for new self-reported CHD of 1.63 (95% CI 1.11–2.40); it was 1.93 (95% CI 1.31–2.84) for having an ICD code for new-onset CHD.

Personnel found to have PTSD at screening conducted at baseline or one of the two follow-ups had an OR for self-reported new CHD of 1.66 (95% CI 1.10–2.50) when partially adjusted for covariates, including deployment status, demographics, pay grade, service branch, body-mass index, smoking and drinking history, fitness level, diabetes, and hypertension. However, further adjustment for depression and anxiety attenuated the OR to a nonsignificant level: 1.27 (95% CI 0.76–2.12). At neither level of adjustment was PTSD significantly associated with a CHD diagnosis code.

"The findings raise interesting questions about the pathophysiological links between combat, PTSD, and cardiovascular disease," according to Dr Rachel Lampert (Yale University School of Medicine, New Haven, CT) in an accompanying editorial[2], "[and] suggest that combat experience should be considered a risk factor for CHD." The study's large size and prospective, longitudinal design with adjustment for covariates "strongly support the definitive nature of the results."

The analysis suggests that combat experience is a stronger influence on new CHD risk than PTSD, she writes, and the relationship of the two risk factors is likely to be complex. "While PTSD did not explain the entire impact of combat on cardiovascular risk, it does appear to have at least some mediating role."

Lampert observed that "psychological stress increases sympathetic and decreases vagal activity, and ongoing stressors have longer-term effects on the body through the wear and tear of recurrent sympathetic activation." The physiologic damage from combat experience may be enough to induce CHD in some people; for others, "the amplification and repetition of this response due to PTSD may mediate some of the effects of the initial combat-related stress."

Neither the study's authors nor Lampert disclosed any conflicts of interest.


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