Deployment exposures contribute to abnormal lung function in veterans
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Key takeaways:
- Deployment-related distal lung disease was frequently reported among veterans.
- Lung function following deployment differs based both on type of respiratory disease and intensity of deployment exposures.
Following military deployment, veterans who served in Southwest Asia and Afghanistan had poorer lung function if they experienced more intense inhalation exposures, according to results published in Respiratory Medicine.
Additionally, FEV1/FVC ratio fell annually at a significant rate among veterans with deployment-related distal lung disease, according to researchers.
“These findings provide insight into which symptomatic veterans may be at risk for accelerated declines in lung function after deployment,” Lauren M. Zell-Baran, PhD, MPH, assistant professor of epidemiology at National Jewish Health, and Cecile S. Rose, MD, MPH, professor of medicine and occupational pulmonologist at National Jewish Health, told Healio in a statement.
“Identifying those with both large and small airways disease, as well as those with more intense deployment exposures, is key for prioritizing clinical follow-up and medical surveillance,” they continued.
In this study, Zell-Baran, Rose and colleagues analyzed 219 veterans (mean age, 40 years; 88% men) previously deployed to Southwest Asia and Afghanistan and evaluated for occupational lung disease to see how lung function differs based on exposures and deployment-related respiratory disease diagnoses.
Considering the entire cohort, total median deployment length was 18 months. Most of these individuals had been deployed to Iraq (41%) or both Iraq and Afghanistan (31%). Deployment to Afghanistan only was less common (19%).
When asked about deployment exposures, 95% of veterans reported experiencing high-intensity exposure (more than weekly) to diesel exhaust, and 78% experienced high-intensity exposure to burn pits. A smaller proportion of veterans reported high-intensity exposure to sandstorms (19%) and combat generated dust (16%).
Despite these exposures, researchers observed normal spirometry on average following deployment. Small percentages of veterans had an obstructive (8%) or a restrictive pattern on spirometry (5%) at their initial evaluation following deployment.
Most veterans (n = 192) had spirometry data from at least two pulmonary function tests, whereas the remainder (n = 27) had data from just one test.
Deployment-related distal lung disease (DDLD) involving the small airways was a frequent diagnosis in this study population (41%), followed by a combination of DDLD and deployment-related asthma (24%), deployment-related asthma alone (13%), and other deployment-related respiratory diseases (22%), such as rhinitis and/or sinusitis (n = 11) and respiratory symptoms only (n = 27).
Five years after first deployment, researchers found the lowest estimated mean spirometry measurements among veterans with both DDLD and deployment-related asthma compared with the three other deployment-related respiratory disease types.
According to researchers, having a combination of DDLD and deployment-related asthma was linked to reduced FEV1 (vs. all disease groups), FVC (vs. deployment-related asthma alone or other deployment-related respiratory diseases), FEV1/FVC ratio (vs. DDLD alone) and diffusing capacity of the lungs for carbon monoxide (DLCO; vs. deployment-related asthma alone).
In a linear mixed model that accounted for several variables (age, sex, height, weight, family history of lung disease and smoking), lung function in the DDLD alone group fell each year (FEV1/FVC, –0.2% per year), according to researchers. This decline was not found to be significant among those with both diseases, deployment-related asthma alone or other deployment-related respiratory diseases but trended in the same direction.
“Initially, we were surprised by the variability in annual declines in lung function measurements among all diagnosis groups,” Zell-Baran told Healio. “These differences may be explained in part by availability of treatment options for those with asthma compared to those with deployment-related distal lung disease such as bronchiolitis. Additionally, because pre-deployment lung function measurements are not obtained on most military personnel, our findings may underestimate lung function changes had pre-deployment data been available.”
When looking at lung function in relation to deployment exposures, researchers observed that this measure was more abnormal/lower with greater intensity inhalational exposure.
Grouped by exposure intensity, veterans with medium/high inhalational exposure vs. low exposure had several worse measures of lung function: FEV1, FVC, FEV1/FVC and forced expiratory flow between 25% and 75% of vital capacity (FEF25-75).
“Asking patients about their inhalational exposures during deployment can inform risk of lung function decline and should be incorporated into the clinical care of veterans,” Rose said.
Lastly, when estimated at 5 years since deployment, active-duty veterans (n = 173) had worse FVC and total lung capacity than veterans in the reserves (n = 26). Between military contractors and active-duty veterans, researchers observed reduced DLCO in the contractor group.
As time passed, FEV1, FVC and FEF25-75 stayed stable or increased for active-duty veterans and veterans in the reserves, whereas these measures declined for contractors.
“As we and others continue to monitor the lung health of veterans following deployment, additional findings and insights are likely to emerge,” Zell-Baran said. “Along with changes in lung function, systematic monitoring of respiratory symptoms, quality of life and the occurrence of longer latency diseases will be important. Future research also should be designed to answer questions about both pharmacologic and nonpharmacologic interventions that can improve lung function and quality of life for these patients.”