Respiratory Symptoms among Military Personnel Deployed to Iraq/Afghanistan
Abstract & Commentary
By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley Medical Center; Clinical Professor, Stanford University School of Medicine, Section Editor, HIV, is Associate Editor for Infectious Disease Alert.
Synopsis: Data from the large prospective Millenium Cohort Study were examined with respect to respiratory symptoms, chronic bronchitis/emphysema, and asthma. Personnel deploying to Iraq or Afghanistan had higher rates of newly reported respiratory symptoms than non-deployers. This was seen only in Army and Marine Corps members who participated in land-based deployments.
Source: Smith B, et al. Newly reported respiratory symptoms and conditions among military personnel deployed to Iraq and Afghanistan: A prospective population-based study. Am J Epidemiology. 2009;(epub 22 Oct): 1-9.
In this study, 77,047 participants from the U.S. Department of Defense prospective Millenium Cohort Study were enrolled in 2001; 55,021 underwent follow-up screening in 2004-2006. New-onset respiratory symptoms were defined as persistent or recurring cough or dyspnea reported at follow-up, with no previous report at baseline. Chronic bronchitis, emphysema, and asthma were defined as member-reported physician diagnoses. Multivariate analyses were conducted on the cohort. For deployed vs. non-deployed U.S. Army personnel, an unadjusted odds ratio (OR) of 1.79 for development of new-onset respiratory symptoms was observed. After adjustment for deployment status, sex, birth year, marital status, race/ethnicity, education, smoking status, service branch, service component, military rank, and occupation, the adjusted odds ratio (AOR) remained 1.73. For Marine Corps personnel, the OR and AOR were 1.51 and 1.49, respectively. For Air Force and Navy/Coast Guard personnel, no significant association between deployment and respiratory symptoms was seen. No significant relationship between deployment and the diagnosis of chronic bronchitis/emphysema or asthma was seen in Army, Air Force, Navy/Coast Guard, or Marine Corps personnel.
Concern has been raised about possible increased rates of respiratory illnesses in military members during and following deployments to Iraq and Afghanistan. This large, prospective cohort study seems to confirm a signal supporting these previously anecdotal reports. Further analysis of the data show that specific exposure, rather than deployment, in general, is associated with new-onset respiratory symptoms. This is supported by the fact that elevated odds of developing respiratory symptoms were associated with land-based, rather than sea-based, deployment. A trend toward a dose-response effect was seen with longer deployments, typically performed by Army troops (often 12-15 months "boots on the ground"), being more commonly associated with new-onset respiratory symptoms.
My own anecdotal experience with four deployments to Iraq and one to Afghanistan since 2003 suggests that environmental exposure is likely multifactorial, with frequent exposure to dust (which is like fine talcum powder in Iraq) being the largest contributing factor. During sand storms, the daylight turns to a weird, dark orange glow, with visibility reduced to just a few meters, and these conditions can persist for days at a time. Concern has also recently been raised by the Air Force Times about the environmental effects of burn pits, particularly at the large Joint Base at Balad (about 80 km north of Baghdad), but the preliminary information I've read elsewhere in the lay press suggests that this is likely not a significant exposure contributing to respiratory illness. Speaking with Iraqi doctors and parents of children since 2006, I've also come away with the impression that they are seeing more frequent and prolonged respiratory symptoms in civilians in Iraq (especially children) as well. This may be related to the prolonged drought Iraq has experienced over the last several years due to decreased rainfall and to desertification from the diversion of water by Turkey from the Tigris and Euphrates Rivers and by Saddam Hussein's draining of the marshes in southern Iraq during the 1990s.
While this study strongly suggests that a "signal" is present that links deployment to Southwest Asia and new-onset respiratory symptoms, more work needs to be done. This would include more detailed evaluations and characterization of the illnesses in individual service members, additional teasing out of the survey data, and environmental assessment studies conducted in Iraq and Afghanistan.