MILITARY MEDICINE, 179, 5;540, 2014
A Retrospective Cohort Study of Military Deployment and Postdeployment Medical Encounters for Respiratory Conditions Joseph H. Abraham, ScD*; Angie Eick-Cost, PhDf; Leslie L Clark, PhDf; Zheng Hu, MSf; Coleen P. Baird, MD, MPH*; COL Robert DeFraites, MC USA (Ret.)t; COL Steven K. Tobler, MC USAf; CPT Erin E. Riohards, MS USAf; Jessica M. Sharkey, MPH*; COL Robert J. Lipnick, (Ret.) MS USAf; CAPT Sharon L. Ludwig, MC USCGf ABSTRACT Deployed military personnel are exposed to inhalational hazards that may increase their risk of chronic lung conditions. This evaluation assessed associations between Operation Iraqi Freedom (OIF) deployment and postdeployment medical encounters for respiratory symptoms and medical conditions. This retrospective cohort study was conducted among military personnel who, between January 2005 and June 2007, were deployed to either of two locations with bum pits in Iraq, or to either of two locations without bum pits in Kuwait. Incidence rate ratios (IRRs) were estimated using two nondeployed reference groups. Rates atnong personnel deployed to bum pit locations were also compared directly to those among personnel deployed to locations without bum pits. Significantly elevated rates of encounters for respiratory symptoms (IRR = 1.25; 95% confidence interval [CI]; 1.20-1.30) and asthma (IRR = 1.54; 95% CI; 1.33-1.78) were observed among the formerly deployed personnel relative to U.S.-stationed personnel. Personnel deployed to bum pit locations did not have significantly elevated rates for any of the outcomes relative to personnel deployed to locations without bum pits. These results are consistent with the hypothesis that OIF deployment is associated with subsequent risk of respiratory conditions. Elevated medical encounter rates were not uniquely associated with bum pits.
INTRODUCTION Since 2001, more than 2 million U.S. military personnel have been deployed to southwest Asia.'"^ Deployments typically last between 6 and 12 months, and vary in length by military branch and mission requirements. During deployment, personnel are exposed to inhalation hazards originating from local and regional sources, including the desert environment, unregulated regional industry, vehicles, diesel-powered generators and other machinery, and waste fires.'*"' Ambient air quality in areas of southwest Asia hosting large numbers of U.S. troops has been characterized. Ambient paniculate matter (PM) levels are routinely elevated in Iraq and Kuwait.'*"'' An assessment at 15 deployment locations found the main particulate pollutants to be geological dust, heavy metal condensates, and smoke from bum pits.'' Bum pits have been used to dispose of solid waste during Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). A burn pit is "an area, not containing a commercially manufactured incinerator or other equipment specifically *U.S. Army Public Health Command, 5158 Blackbawk Road Aberdeen Proving Ground, MD, 21010. tArmed Forces Health Surveillance Center, 11800 Tech Road Silver Spring, MD, 20910. ^Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road Bethesda, MD 20814. The views expressed herein are the views of the author(s) and do not reflect the official policy of the Department of the Army, the Department of Defense, or the U.S. Government. doi; 10.7205/MILMED-D-13-00443
540
designed and manufactured for burning of solid waste, designated for the purpose of disposing of solid waste by buming in the outdoor air at a location with more than 100 attached or assigned personnel and that is in place longer than 90 days." Bum pit emissions, including PM, volatile organic compounds, and polycyclic aromatic hydrocarbons, likely vary because of heterogeneity in the trash stream and use of accelerants.^ Personnel activity pattems, distance from the bum pit site, and meteorological conditions additionally influence bum pit emissions exposures. Bum pit emissions exposures have been implicated as a cause of chronic respiratory illnesses,'°~''' but no study has identified an association between bum pit emissions exposure and postdeployment chronic lung conditions. Among a case series of 38 Soldiers diagnosed with constrictive bronchiolitis, 63% reported exposure to bum pits, although a larger proportion of these patients (86%) reported dust storm exposure.'° Increased frequency of respiratory symptoms and illness during and after deployment, relative to those experienced before deployment, has been reported among OEF- and OIF-deployed military personnel.''*"'^ However, among Millennium Cohort Study (MCS) participants, potential bum pit emissions exposure was not associated with newly reported chronic bronchitis, emphysema, or asthma." We conducted a retrospective cohort study to evaluate associations between deployment to military base camps in Iraq and Kuwait and the development of postdeployment symptoms involving the respiratory system (respiratory symptoms), asthma, and chronic obstructive pulmonary disease (COPD) and allied conditions.
MILITARY MEDICINE, Vol. 179, May 2014
Military Deployment and Respiratory Health
METHODS To conduct this investigation, we merged pre-existing personnel demographic and location data maintained at the Defense Manpower Data Center with diagnostic and discharge records for ambulatory medical encounters and hospitalizations maintained in the Defense Medical Surveillance System. Using these data, we estimated incidence rates of asthma, COPD and allied conditions, and respiratory symptoms among personnel who had been deployed to specific locations in southwest Asia (including locations with and without bum pits), or who were stationed in the United States or the Republic of Korea.
Study Population and Study Design Active component U.S. military personnel were eligible for inclusion in the exposure groups on the basis of documented deployment for at least 31 days between January 2005 and June 2007 to Joint Base Balad (JBB), or Camps Taji, Buehring, or Arifjan. The Iraqi locations (JBB and Taji) were selected to represent deployment locations with bum pits; the Kuwaiti locations (Buehring and Arifjan) were selected because they have environmental conditions similar to those at JBB and Taji, but lack bum pits. We identified a primary reference group consisting of active component Service Members stationed in the United States who had not been deployed in support of OIF or OEF as of April 15, 2006, and who were deemed fit for deployment, as evidenced by having a documented OIF or OEF deployment after June 2007. Personnel deployed before April 15, 2006 were excluded from the U.S.-stationed group. Because no Navy personnel and only a few Marines (
A Retrospective Cohort Study of Military Deployment and Postdeployment Medical Encounters for Respiratory Conditions Joseph H. Abraham, ScD*; Angie Eick-Cost, PhDf; Leslie L Clark, PhDf; Zheng Hu, MSf; Coleen P. Baird, MD, MPH*; COL Robert DeFraites, MC USA (Ret.)t; COL Steven K. Tobler, MC USAf; CPT Erin E. Riohards, MS USAf; Jessica M. Sharkey, MPH*; COL Robert J. Lipnick, (Ret.) MS USAf; CAPT Sharon L. Ludwig, MC USCGf ABSTRACT Deployed military personnel are exposed to inhalational hazards that may increase their risk of chronic lung conditions. This evaluation assessed associations between Operation Iraqi Freedom (OIF) deployment and postdeployment medical encounters for respiratory symptoms and medical conditions. This retrospective cohort study was conducted among military personnel who, between January 2005 and June 2007, were deployed to either of two locations with bum pits in Iraq, or to either of two locations without bum pits in Kuwait. Incidence rate ratios (IRRs) were estimated using two nondeployed reference groups. Rates atnong personnel deployed to bum pit locations were also compared directly to those among personnel deployed to locations without bum pits. Significantly elevated rates of encounters for respiratory symptoms (IRR = 1.25; 95% confidence interval [CI]; 1.20-1.30) and asthma (IRR = 1.54; 95% CI; 1.33-1.78) were observed among the formerly deployed personnel relative to U.S.-stationed personnel. Personnel deployed to bum pit locations did not have significantly elevated rates for any of the outcomes relative to personnel deployed to locations without bum pits. These results are consistent with the hypothesis that OIF deployment is associated with subsequent risk of respiratory conditions. Elevated medical encounter rates were not uniquely associated with bum pits.
INTRODUCTION Since 2001, more than 2 million U.S. military personnel have been deployed to southwest Asia.'"^ Deployments typically last between 6 and 12 months, and vary in length by military branch and mission requirements. During deployment, personnel are exposed to inhalation hazards originating from local and regional sources, including the desert environment, unregulated regional industry, vehicles, diesel-powered generators and other machinery, and waste fires.'*"' Ambient air quality in areas of southwest Asia hosting large numbers of U.S. troops has been characterized. Ambient paniculate matter (PM) levels are routinely elevated in Iraq and Kuwait.'*"'' An assessment at 15 deployment locations found the main particulate pollutants to be geological dust, heavy metal condensates, and smoke from bum pits.'' Bum pits have been used to dispose of solid waste during Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). A burn pit is "an area, not containing a commercially manufactured incinerator or other equipment specifically *U.S. Army Public Health Command, 5158 Blackbawk Road Aberdeen Proving Ground, MD, 21010. tArmed Forces Health Surveillance Center, 11800 Tech Road Silver Spring, MD, 20910. ^Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road Bethesda, MD 20814. The views expressed herein are the views of the author(s) and do not reflect the official policy of the Department of the Army, the Department of Defense, or the U.S. Government. doi; 10.7205/MILMED-D-13-00443
540
designed and manufactured for burning of solid waste, designated for the purpose of disposing of solid waste by buming in the outdoor air at a location with more than 100 attached or assigned personnel and that is in place longer than 90 days." Bum pit emissions, including PM, volatile organic compounds, and polycyclic aromatic hydrocarbons, likely vary because of heterogeneity in the trash stream and use of accelerants.^ Personnel activity pattems, distance from the bum pit site, and meteorological conditions additionally influence bum pit emissions exposures. Bum pit emissions exposures have been implicated as a cause of chronic respiratory illnesses,'°~''' but no study has identified an association between bum pit emissions exposure and postdeployment chronic lung conditions. Among a case series of 38 Soldiers diagnosed with constrictive bronchiolitis, 63% reported exposure to bum pits, although a larger proportion of these patients (86%) reported dust storm exposure.'° Increased frequency of respiratory symptoms and illness during and after deployment, relative to those experienced before deployment, has been reported among OEF- and OIF-deployed military personnel.''*"'^ However, among Millennium Cohort Study (MCS) participants, potential bum pit emissions exposure was not associated with newly reported chronic bronchitis, emphysema, or asthma." We conducted a retrospective cohort study to evaluate associations between deployment to military base camps in Iraq and Kuwait and the development of postdeployment symptoms involving the respiratory system (respiratory symptoms), asthma, and chronic obstructive pulmonary disease (COPD) and allied conditions.
MILITARY MEDICINE, Vol. 179, May 2014
Military Deployment and Respiratory Health
METHODS To conduct this investigation, we merged pre-existing personnel demographic and location data maintained at the Defense Manpower Data Center with diagnostic and discharge records for ambulatory medical encounters and hospitalizations maintained in the Defense Medical Surveillance System. Using these data, we estimated incidence rates of asthma, COPD and allied conditions, and respiratory symptoms among personnel who had been deployed to specific locations in southwest Asia (including locations with and without bum pits), or who were stationed in the United States or the Republic of Korea.
Study Population and Study Design Active component U.S. military personnel were eligible for inclusion in the exposure groups on the basis of documented deployment for at least 31 days between January 2005 and June 2007 to Joint Base Balad (JBB), or Camps Taji, Buehring, or Arifjan. The Iraqi locations (JBB and Taji) were selected to represent deployment locations with bum pits; the Kuwaiti locations (Buehring and Arifjan) were selected because they have environmental conditions similar to those at JBB and Taji, but lack bum pits. We identified a primary reference group consisting of active component Service Members stationed in the United States who had not been deployed in support of OIF or OEF as of April 15, 2006, and who were deemed fit for deployment, as evidenced by having a documented OIF or OEF deployment after June 2007. Personnel deployed before April 15, 2006 were excluded from the U.S.-stationed group. Because no Navy personnel and only a few Marines (
