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A6078 - Longitudinal Analysis of Spirometry in Symptomatic Military Deployers Returning from Iraq and Afghanistan
Author Block: L. Zell-Baran1, S. D. Krefft2, M. Strand2, J. Wolff1, E. Gottschall2, C. Rose2; 1National Jewish Health, Denver, CO, United States, 2University of Colorado Anschutz Medical Campus, Aurora, CO, United States; National Jewish Health, Denver, CO, United States.
Rationale: Many military personnel deployed to Southwest Asia, primarily Iraq and Afghanistan, since 09/11/2001 report exposure to respiratory hazards including burn pit combustion products, diesel emissions, combat dusts, and sandstorms. Some have returned with exertional respiratory symptoms and have undergone serial pulmonary function testing (PFT). Whether symptomatic deployers suffer accelerated declines in lung function following last deployment is unknown. We examined longitudinal changes in forced expiratory volume - one second (FEV1) in symptomatic post-9/11 deployers undergoing clinical evaluation. Methods: We analyzed changes in FEV1 from 71 post-9/11 deployers who had at least two high quality spirometry tests at least three months apart. We developed a mixed linear model and assessed changes over time considering deployment duration and frequency, as well as individual variability (including gender, race, height, weight and age). Model fit was evaluated using a likelihood ratio test. Deployment duration and frequency were collected via questionnaire, and PFT data were obtained from medical records with IRB approval. Results: The majority (89%) were male with a mean age of 40.42 years [standard deviation (SD) 9.89]. None reported current cigarette smoking, 31% reported past smoking, and 69% reported never smoking. Deployers had between two and eight qualifying PFTs, with between 0.25 and 4.68 years (median 0.96) of follow-up. Latency of symptom onset averaged 3.63 years (SD 3.18) after first deployment. Time between last deployment and first PFT ranged from -0.73 to 13.36 years (median 2.86). Deployers had 2.01 (SD 1.34) deployments on average with 18.45 (SD 16.66) total months deployed. Overall mean FEV1 did not decline over time but modestly increased at a rate of 87.6 ml/year. During follow-up, 29 (41%) deployers had modest declines in FEV1; two had significant FEV1 declines exceeding 15%. We saw a clear, but non-statistically significant, relationship between FEV1 decline and higher exposure (based on deployment duration and frequency). Conclusions: Following last deployment, most symptomatic military personnel in our clinic population had no decline in FEV1. A few had substantial longitudinal FEV1 declines. Study limitations include the short follow-up time, small sample size, and lack of pre-deployment lung function testing for comparison. Future directions include assessment of additional PFT parameters (lung volumes, diffusion capacity, exercise variables), diagnosis and treatment effects, and deployment location and timing. Specific exposures (burn pits, diesel emissions, etc.) or exposure events may play a role in longitudinal lung function and also will be investigated.