By Annette M. Boyle
SEATTLE – While combat has long been known to increase the risk of musculoskeletal injuries, post-traumatic stress disorder (PTSD), other mental health issues and traumatic brain injury, another serious condition has now been added to the list: coronary heart disease.
Even in the absence of physical injury, combat triggers stress responses, which can lead to the development of PTSD. Those same factors also might contribute to the development of coronary heart disease (CHD).
“There are a number of potential biological phenomena associated with stress that may increase risk of CHD, such as increased sympatho-adrenal activity, higher blood pressure, increased coronary vasoconstriction and enhanced platelet aggregation,” explained Edward J. Boyko, MD, staff physician at the VA Puget Sound and a professor in the Department of Medicine at the University of Washington in Seattle.
For a recent study, Boyko was joined by other VA researchers based in Seattle and Durham, NC, as well as researchers from the Naval Health Research Center in San Diego and Walter Reed National Military Medical Center, in reviewing the cases of 60,025 current and former servicemembers, all participants in the Millennium Cohort Study from 2001 to 2008. The study team focused on self-reported cases of new CHD, while also including 23,794 servicemembers on active duty who had a diagnosis of CHD in their medical records. 1
When the researchers compared individuals deployed to Iraq and Afghanistan who experienced combat to those who did not, they found a 63% increase in CHD among those who self-reported the disease. Individuals who reported combat experience had nearly twice the odds of having a diagnosis code for new-onset CHD vs. deployed servicemembers who never saw battle. New CHD was self-reported by 627 members of the overall cohort over a mean follow-up of 5.6 years.
In their report, which appeared in the journal Circulation, the researchers identified no association between CHD and deployment, even considering length of deployment and total days of deployment, instead concluding, “Exposure to combat appears to be a more profound stressor associated with mental and physical conditions than deployment alone or the number of cumulative days deployed.”
Active duty servicemembers newly diagnosed with CHD were more likely to be male, older, married, obese and current smokers. They more frequently reported no or little drinking and were more likely to have depression and hypertension.
New cases of CHD occurred at a rate of about 1% in the veterans and active duty servicemembers in the study, but the results suggests that, over the longer term, “young military personnel who experienced combat during the recent conflicts may have a heightened risk for the development of CHD,” noted the authors.
Relationship With PTSD
The researchers also analyzed whether PTSD increased the risk of developing coronary heart disease, noting, “Prior studies have suggested that combat exposure has an indirect effect on physical health outcomes mediated through PTSD, with PTSD having a direct effect.”
The researchers said they wanted to better understand the role of specific deployment experiences and PTSD on the incidence of newly reported CHD soon after deployment.
“We thought it more likely that there would be a PTSD association, based on previous research, but other studies had not looked prospectively at the data,” Boyko said.
Initial analyses indicated a relation possibly existed between the two conditions. Those who had PTSD at the baseline screening or in one of two follow-ups had a 66% increase in risk of self-reported new-onset CHD after adjustment for deployment status, demographics, pay grade, service branch, body-mass index, smoking, drinking history, fitness level, diabetes and hypertension.
Adjusting for depression and anxiety, however, erased any significant correlation in the self-reporting group.
Among those with diagnostic codes indicating CHD, there was no correlation with PTSD in any of the multivariable models, even without adjusting for anxiety and depression. The authors noted, however, that “the lack of an association when the medical records were used may have been influenced by reduced power as a result of the smaller study population and potential under-diagnosis of CHD in the medical records.”
“There is considerable overlap between PTSD, anxiety and depression. Our results would suggest that PTSD is a marker for other mental health conditions associated with coronary heart disease rather than PTSD itself,” Boyko told U.S. Medicine.
In support of that hypothesis, the researchers found depression was significantly associated with higher risk of medically diagnosed PTSD. Among those with PTSD, 57% also had depression and 38% met the criteria for anxiety.
The authors observed that “the magnitude of the associations between combat experiences and CHD was attenuated when PTSD and other covariates were added to the models, which suggests that these factors could be part of the causal pathway (e.g., PTSD or covariates such as depression may play a role in the association of combat deployment and CHD).
In an accompanying editorial, Rachel Lampert, MD, professor at the Yale University School of Medicine in New Haven, CT, wrote that up to 20% of returning veterans from recent conflicts meet diagnostic criteria for PTSD and many more meet the diagnostic criteria for any psychological disorder. “These mental health problems stem directly from combat with a dose-response relationship — the more firefights the soldiers had experienced, the higher the rate of PTSD and depression,” she noted.2
“The findings raise interesting questions about the pathophysiological links between combat, PTSD, and cardiovascular disease,” Lampert added.
Although she agreed that combat should be considered a risk factor in CHD, and that the study’s large size, prospective design and adjustments for covariates support the definitive nature of its results, Lampert did not fully discount the role of PTSD, suggesting, “While PTSD did not explain the entire impact of combat on cardiovascular risk, it does appear to have at least some mediating role.”
1 Crum-Cianflone N, Bagnell M, Schaller D, et al. Impact of combat deployment and post-traumatic stress disorder on new-onset coronary heart disease among us active duty and reserve forces. Circulation. 2014 May 6;129(18):1813-20.
2 Lampert R. Veterans of combat: still at risk when the battle is over. Circulation. 2014 May 6;129(18):1797-8
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