Issue: March 2016
December 14, 2015
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Combat injury severity linked to elevated risk for hypertension, CAD, diabetes, CKD

Issue: March 2016
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A retrospective study of U.S. veterans of combat operations in Iraq and Afghanistan showed that the more severe a veteran’s combat injury, the greater the risk for development of hypertension, CAD, diabetes and chronic kidney disease.

Ian J. Stewart, MD, from David Grant Medical Center, Travis Air Force Base, California, and colleagues conducted a retrospective cohort study of 3,845 service members critically injured in Iraq or Afghanistan for whom there were complete data between Feb. 1, 2002, and Feb. 1, 2011, to determine a relationship between markers of injury severity (expressed via an injury severity score) and onset of hypertension, CAD, diabetes and chronic kidney disease (CKD). Patients with any of those conditions before their injury were excluded.

“I have seen firsthand that our soldiers, sailors, airmen and marines get the finest trauma and follow-up care. However, the long-term consequences of their injuries are not known,” Stewart told Cardiology Today. “I wanted to find out if combat injury was associated with the subsequent development of medical problems.”

Median follow-up — during which there were 45 deaths, 551 new cases of hypertension, 55 new cases of CAD, 84 new cases of diabetes and 47 new cases of CKD — ranged from 1.1 years to 2.8 years in those who died or developed a chronic disease, and it was 4.3 years for those who developed no diseases.

Kidney injury a factor

Stewart and colleagues found that patients who developed at least one of the outcomes were older, had a higher average injury severity score and were more likely to have acute kidney injury than those who did not.

Those who died or had long-term disabilities had greater rates of head/neck and chest injuries and lower rates of extremity injuries than those who did not, they found.

After adjustment for age, race, mean arterial BP, heart rate, burn injury and acute kidney injury, they determined that, independent of the risk for mortality, each five-point increase in injury severity score was associated with a 6% increase in risk for hypertension (HR = 1.06; 95% CI, 1.02-1.09), a 13% increase in risk for CAD (HR = 1.13; 95% CI, 1.03-1.25), a 13% increase in risk for diabetes (HR = 1.13; 95% CI, 1.04-1.23) and a 15% increase in risk for CKD (HR = 1.15; 95% CI, 1.04-1.27).

In addition, acute kidney injury was associated with increased risk for developing hypertension (HR = 1.66; 95% CI, 1.28-2.14) and CKD (HR = 4.79; 95% CI, 2.53-9.08), according to the researchers.

“There are a variety of possible reasons why combat injury could be associated with these outcomes,” Stewart said in an interview. “Firstly, an episode of trauma results in a brisk inflammatory response. It’s possible that this inflammation is the reason we observed trauma to be associated with all these outcomes. It is also possible that post-traumatic stress disorder (PTSD) is playing a role. We know that PTSD increases markers of inflammation and this might increase the risk for chronic disease development. PTSD is also associated with weight gain and substance abuse, both of which might also play a role. Lastly, it’s important to realize that prior to injury, most of these patients were young men in peak physical condition. After they were wounded, they spent a long time in the hospital and in rehabilitation. Many of them also had amputations. Therefore, it will be much harder for them to stay in shape physically compared to before their injury. These prolonged functional limitations may play a role in the long-term risk for hypertension, diabetes, CAD and CKD.”

Age was a predictor of hypertension (HR = 1.05; 95% CI, 1.04-1.07), CAD (HR = 1.07; 95% CI, 1.03-1.11) and diabetes (HR = 1.08; 95% CI, 1.05-1.11), whereas blacks were more likely than whites to develop hypertension (HR = 1.69; 95% CI, 1.26-2.27), they found.

Much higher rates

“When compared with historical data, the rates of [hypertension], CAD and [diabetes] are much higher than would be expected,” Stewart and colleagues wrote. “For example, the incidence rates of [hypertension], CAD and [diabetes] for the most severely injured patients were twofold to fourfold higher than published rates for the overall U.S. military population. These findings could have profound implications for both those wounded in combat and for federal health systems.”

Stewart told Cardiology Today that “if these findings can be replicated, this study suggests that the adverse consequences of being injured are not limited to the initial recovery phase. The implication is that service members who sustained a combat injury might suffer CV consequences for decades to come. This would lead to decreased quality and quantity of life as well as increased health care costs.”– by Erik Swain

For more information:

Maj. Ian J. Stewart, MD, can be reached at David Grant Medical Center, Clinical Investigation Facility, 101 Bodin Circle, Travis AFB, CA 94535; email: ian.stewart@us.af.mil

Disclosure: The researchers report no relevant financial disclosures.