JOINT BASE SAN ANTONIO-FORT SAM HOUSTON, Texas —
Researchers at Brooke Army Medical Center, Walter Reed National Military Medical Center, and Fort Belvoir Community Hospital recently completed the largest prospective study of redeploying military personnel with chronic respiratory symptoms.
This study was initiated to determine the types of pulmonary disease associated with chronic deployment-related respiratory symptoms and to serve as the basis for future evaluations.
The Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures, or STAMPEDE III, led by Dr. Michael J. Morris, BAMC pulmonary/critical care physician, is the third iteration of deployment-related studies. Similar studies, STAMPEDE I and STAMPEDE II, were completed in 2014 and 2019 respectively.
“Military deployments since 2003 are unique because of the number of areas our service members have deployed to and different types of particulate matter to which they were exposed,” Morris said. “This prospective study, which has been ongoing for the seven years, represents the largest and most comprehensive clinical evaluation of military personnel with deployment-related respiratory symptoms.”
STAMPEDE III enrolled 450 active duty and retired military personnel who were deployed for a minimum of six months in Southwest Asia (Iraq, Afghanistan, Kuwait or Qatar) who noted chronic respiratory symptoms, primarily shortness of breath or decreased exercise tolerance, after being deployed.
All participants underwent a standardized evaluation consisting of pulmonary function testing; CT scan of the chest; methacholine challenge testing (also known as a bronchoprovocation test); laryngoscopy (to examine the larynx), cardiopulmonary exercise testing, and fiberoptic bronchoscopy.
Three hundred eighty of the participants completed the standardized protocol. The primary investigators in this study reviewed all available clinical data provided to determine the clinical diagnosis.
“We put these study participants through a more formal evaluation process,” Morris said. “There have been no other studies like this, where we systematically investigated service members who deployed to these areas. We were looking to see if anyone had asthma, interstitial lung disease, constrictive bronchiolitis, or other pulmonary disorders that we could associate with deployment.”
According to the American Lung Association, interstitial lung disease is an umbrella term for a large group of disorders that cause scarring (fibrosis) of the lungs. The scarring causes stiffness in the lungs which makes it difficult to breathe.
Participants were classified into seven major categories to include: asthma, airway hyper-responsiveness, undiagnosed exertional dyspnea (shortness of breath during exercise), airway disorders (both upper and large airway), obstructive lung disease (including emphysema, bronchiectasis and chronic obstructive pulmonary disease), diffuse lung disease (widespread interstitial or small airway disorders such as pneumonitis or bronchiolitis), and nonspecific pulmonary function testing.
“We found very similar results to what we found in STAMPEDE I,” Morris said. STAMPEDE I was a much smaller study of 50 service members with acute symptoms within 6 months of returning from deployment. Nearly 40 percent of these individuals had no specific pulmonary findings.
“In the largest group of STAMPEDE III, about 30 percent, despite all the testing we did, we didn’t find any specific abnormalities,” Morris said. “They were short of breath, and they couldn’t exercise as well, but we couldn’t find anything specific. Another 20 percent had asthma, which was not surprising considering asthma is the most common lung disease we diagnose in a population this age.
“These were all people with new symptoms, not people who were previously diagnosed with asthma,” Morris added. “However, there is no way to determine whether the asthma started while they were deployed or was aggravated by deployment, but they clearly had symptoms when they returned from deployment.”
A smaller percentage of the participants showed signs of airway and laryngeal disorders, and only six patients were identified with interstitial or diffuse lung diseases.
“There were a few patients with diffuse lung diseases, so we are not saying nobody develops these,” Morris said. “But there are very few and this matches up with our clinical experience. The findings go along with what you would find in the typical military population.”
Based on the study findings, Morris believes that military personnel should be evaluated the same way the general population is evaluated and the use of lung biopsies should be very limited.
“We shouldn’t be doing anything outside our normal standard of care, to be looking for unusual diseases first,” he said. “We don’t have evidence from this study that anything unusual is occurring. However, it is important to document their symptoms, their relationship to deployment, and ensure a complete and accurate diagnosis is made.”
Morris also noted that smoking, age, body weight, allergies and other factors such as sleep apnea and reflux play a key role in the respiratory health of military members.
“The bottom line is there is very limited evidence that deployment causes significant lung disease in a large number of our deployers,” Morris said. “It definitely can cause symptoms, but we are not seeing a big influx of service members with severe respiratory issues or lung diseases. They still need to be evaluated and our responsibility to each service member is to provide a timely and accurate evaluation.”
To see the full study, either visit https://journal.chestnet.org/article/S0012-3692(20)30156-2/abstract or https://pubmed.ncbi.nlm.nih.gov/32017933/.