Discussion
The AHOBPR was established in response to mounting concerns that service members and veterans were experiencing adverse health effects that might be attributable to deployment-related exposures. Nearly half of all patients currently enrolled in the AHOBPR report dyspnea, and about one-third have decreased exercise tolerance and/or cough. Of those who completed the questionnaire and the subsequent in-person and generalized AHOBPR examination, our interim analysis showed that about half were assigned a respiratory diagnosis. Yet for many veterans, their breathing symptoms remained unexplained or did not respond to treatment.
While the AHOBPR and related examinations address the needs of many veterans, others may require more comprehensive examination. The PDCEN attends to the latter by providing more detailed and comprehensive clinical evaluations of veterans with deployment-related respiratory health concerns and seeks to learn from these evaluations by analyzing data obtained from veterans across sites. As such, the PDCEN hopes not only to improve the health of individual veterans, but also create standard practices for both VA and non-VA community evaluation of veterans exposed to respiratory hazards during deployment.
One of the major challenges in the field of postdeployment respiratory health is the lack of clear universal language or case definitions that encompass the veteran’s clinical concerns. In an influential case series published in 2011, 38 (77%) of 49 soldiers with history of airborne hazard exposure and unexplained exercise intolerance were reported to have histopathology consistent with constrictive bronchiolitis on surgical lung biopsy.14 Subsequent publications have described other histopathologic features in deployed military personnel, including granulomatous inflammation, interstitial lung disease, emphysema, and pleuritis.12-14 Reconciling these findings from surgical lung biopsy with the clinical presentation and noninvasive studies has proved difficult. Therefore, several groups of investigators have proposed terms, including postdeployment respiratory syndrome, deployment-related distal lung disease, and Iraq/Afghanistan War lung injury to describe the increased respiratory symptoms and variety of histopathologic and imaging findings in this population.9,12,22 At present, there remains a lack of consensus on terminology and case definitions as well as the role of military environmental exposures in exacerbating and/or causing these conditions. As HCPs, it is important to appreciate and acknowledge that the ambiguity and controversy pertaining to terminology, causation, and service connections are a common source of frustration experienced by veterans, which are increasingly reflected among reports in popular media and lay press.
A second and related challenge in the field of postdeployment respiratory health that contributes to veteran and HCP frustration is that many of the aforementioned abnormalities described on surgical lung biopsy are not readily identifiable on noninvasive tests, including traditional interpretation of pulmonary function tests or chest CT imaging.12-14,22 Thus, underlying conditions could be overlooked and veterans’ concerns and symptoms may be dismissed or misattributed to other comorbid conditions. While surgical lung biopsies may offer diagnostic clarity in identifying lung disease, there are significant procedural risks of surgical and anesthetic complications. Furthermore, a definitive diagnosis does not necessarily guarantee a clear treatment plan. For example, there are no current therapies approved by the US Food and Drug Administration for the treatment of constrictive bronchiolitis.
Research efforts are underway, including within the PDCEN, to evaluate a more sensitive and noninvasive assessment of the small airways that may even reduce or eliminate the need for surgical lung biopsy. In contrast to traditional pulmonary function testing, which is helpful for evaluation of the larger airways, forced oscillation technique can be used noninvasively, using pressure oscillations to evaluate for diseases of the smaller airways and has been used in the veteran population and in those exposed to dust from the World Trade Center disaster.23-25 Multiple breath washout technique provides a lung clearance index that is determined by the number of lung turnovers it takes to clear the lungs of an inert gas (eg, sulfur hexafluoride, nitrogen). Elevated lung clearance index values suggest ventilation heterogeneity and have been shown to be higher among deployed veterans with dyspnea.26,27 Finally, advanced CT analytic techniques may help identify functional small airways disease and are higher in deployed service members with constrictive bronchiolitis on surgical lung biopsy.28 These innovative noninvasive techniques are experimental but promising, especially as part of a broader evaluation of small airways disease.
AHOBPR clinical evaluations represent an initial step to better understand postdeployment health conditions available to all AHOBPR participants. The PDCEN clinical evaluation extends the AHOBPR evaluation by providing specialty care for certain veterans requiring more comprehensive evaluation while systematically collecting and analyzing clinical data to advance the field. The VA is committed to leveraging these data and all available expertise to provide a clear description of the spectrum of disease in this population and improve our ability to diagnose, follow, and treat respiratory health conditions occurring after deployment to Southwest Asia and Afghanistan.