Predicting Who Is Likely to Face Future Lung Issues
In 2008, Airman 1st Class Zachary Auxilly donned protective gear as he prepared to fight a blaze in Balad, Iraq. here New-onset respiratory symptoms, including cough, dyspnea on exertion, and chest tightness or wheezing in veterans, are associated with deployment to Southwest Asia . U.S. Air Force Photo by Senior Airman Jason Epley
EAST ORANGE, NJ — Despite having seemingly normal lung function tests, many veterans with a history of deployment still experience significant respiratory symptoms and limitations. For these veterans, pulmonary function testing, specifically a test that measures how much oxygen moves from the lungs to the bloodstream when a person inhales, could help predict who might be at risk for future lung problems, according to a recent study.
The study published in the Annals of the American Thoracic Society evaluated the clinical utility of pulmonary function testing parameters among deployment-exposed veterans with preserved spirometry and examined associations with baseline respiratory symptoms, functional limitations, healthcare utilization and longitudinal trajectories. The analysis used the largest national sample of veterans of the Southwest Asia Theater of Military Operations with available pulmonary function testing data, the researchers reported.1
Study authors are affiliated with VA New Jersey Healthcare System in East Orange, NJ, and the San Francisco VA Healthcare System.
More than 4.5 million U.S. servicemembers have deployed to the Southwest Asia Theater of Military Operations since 1990 and most experienced environmental exposures (smoke from burn pits and oil well fires, dust and sand and regional air pollution) and military exposures (combat, weapons, and blast overpressure) during their service.
New-onset respiratory symptoms, including cough, dyspnea on exertion and chest tightness or wheezing, are associated with deployment to the Southwest Asia Theater of Military Operations. Commonly used parameters on pulmonary function tests are typically reported to be within the normal range for most deployed, however, which is known as deployment-exposed veterans with preserved spirometry. More studies are needed to understand the relationship between normal-range pulmonary function testing parameters and long-term outcomes, the investigators pointed out.
“The motivation for this study stemmed from our clinical experience at the Airborne Hazards and Burn Pits Center of Excellence through our Post-Deployment Cardiopulmonary Evaluation Network, where we evaluate veterans with respiratory symptoms,” Michael J. Falvo, PhD, co-director of the Airborne Hazards and Burn Pits Center of Excellence, War Related Illness and Injury Study Center at the VA New Jersey Healthcare System.
“These veterans often had lung function results within normal limits but were noted to have reduced diffusion (isolated low DLCO [diffusing capacity for carbon monoxide]). The clinical evolution of this isolated reduced DLCO over time among these veterans was previously unknown, as there hadn’t been substantial long-term studies into this deployed veteran population. Since pulmonary function testing is the most widely used clinical test to assess lung disease, it is important that clinicians are made aware of changes that can indicate potential adverse outcomes,” Falvo told U.S. Medicine.
In this study, the investigators identified veterans in the VA Airborne Hazards and Open Burn Pit Registry who received healthcare in the VA and had at least one pulmonary function test after the end of their initial deployment (1990 to 2019) and before completion of the registry self-assessment questionnaire (2014 to 2024). The environmental health registry is open to U.S. veterans and servicemembers who were deployed to Southwest Asia Theater of Military Operations or Egypt starting Aug. 2, 1990, or Afghanistan, Djibouti, Syria or Uzbekistan starting Sept. 11, 2001, through Aug. 31, 2021.
The researchers defined deployment-exposed veterans with preserved spirometry as having no airflow obstruction (forced expiratory volume in 1 second-to-forced vital capacity ratio greater than or equal to lower-limit-of-normal or LLN) or restriction (total lung capacity greater than or equal to LLN). They assessed the predictive value of pulmonary function testing parameters for key outcomes using adjusted mixed-effects regression and machine learning. They also examined the longitudinal trajectories of the pulmonary function testing patterns for deployment-exposed veterans with preserved spirometry using statistical analyses. For longitudinal analyses, the authors adjusted for covariates including age, sex, height, weight and smoking status at the follow-up time.
60% Have Breathing Problems
“Of the veterans in the study who were deployed to Southeast Asia, approximately 60% often experience breathing problems, even if their basic lung function tests appear normal,” Anays M. Sotolongo, MD, co-director of the Airborne Hazards and Burn Pits Center of Excellence, War Related Illness and Injury Study Center, VA New Jersey Health Care System, told U.S. Medicine. “This population of veterans is referred to as deployment-exposed veterans with preserved spirometry. Among all pulmonary function test parameters, a reduced diffusing capacity for carbon monoxide (DLCO) was the strongest predictor of future adverse outcomes, including the risk of respiratory symptoms, functional limitations and greater healthcare utilization.”
DLCO, which indicates how well the lungs move oxygen into the blood, can show problems that others miss, Mehrdad Arjomandi, MD, an investigator at San Francisco VA Healthcare System, pointed out to U.S. Medicine.
“A low DLCO turned out to be the best predictor that a veteran would have ongoing or worsening breathing symptoms, trouble with physical activities and more medical visits or hospital care for lung issues,” Arjomandi said. “Over time, veterans with a low DLCO were more likely to develop restrictive lung diseases (where the lungs can’t fully expand), like interstitial lung disease.”
Among the 3,814 eligible veterans with complete data, the study found that 68% reported respiratory symptoms, but most had preserved spirometry (49% were deployment-exposed veterans with preserved spirometry). This was followed by obstructive (28%), restrictive (21%) and mixed (2%) pulmonary function testing patterns. The 1,879 deployment-exposed veterans with preserved spirometry were 37 years-old (plus or minus 10 years), 86% male, 15% current and 19% former smoker, and 64% had a modified Medical Research Council or mMRC score greater than or equal to 1, according to study authors.
Several pulmonary function testing parameters were linked to outcomes, but diffusing capacity (DLCO) was the strongest predictor, showing significant relationships with many outcomes (odds ratios ranging from 0.46 to 0.89, all p<0.05). Among the 289 deployment-exposed veterans with preserved spirometry with follow-up pulmonary function testing 6 years later (plus or minus 4 years), those with baseline isolated reduction in DLCO (less than LLN) were more likely to develop restrictive impairments compared to those with normal DLCO (33% vs.19%, p=0.048), the investigators reported.
The authors concluded that while many deployed veterans with “normal” lung function still experience significant respiratory symptoms and limitations, the DLCO test stands out as the most helpful tool for predicting who might be at risk for future lung issues among these veterans.
“Detecting a reduced DLCO can prompt closer monitoring and potentially quicker referrals for advanced diagnostics or specialty care,” Falvo said. “We advocate for healthcare professionals to provide comprehensive, symptom-driven evaluations rather than relying solely on initial ‘normal’ test results. These evaluations should include measurement of DLCO. We also recommend that symptomatic veterans with an isolated reduction in DLCO be followed more closely over time.”
Limitations of the study include the sample consisted of veterans who voluntarily enrolled in the registry, were receiving care within VA, and had a pulmonary function test performed at a VAMC that was stored as structured data, so the results might not be generalizable to the broader population of deployed Southwest Asia Theater of Military Operations who don’t meet these criteria, the authors explained.
- Zeng S, Jani NC, Sotolongo AM, Luo G, Arjomandi M, Falvo MJ. Clinical Utility of Pulmonary Function Testing in Assessing Longitudinal Outcomes of Deployed Veterans with Preserved Spirometry. Ann Am Thorac Soc. 2025 Jun 12. doi: 10.1513/AnnalsATS.202411-1205OC. Epub ahead of print. PMID: 40505146.
