In the past, for diverse reasons that may include under diagnosis and environmental factors, asthma appeared to be uncommon. As such, Armed forces could afford the luxury of turning away asthmatic recruits, who were otherwise relatively few in number. However, high rates of asthma in many countries present significant challenges to recruitment policy. Indeed, with adult prevalence rates as high as 14-16% in Australia and the United Kingdom (1), and rising trends in many other nations, there is a need to formulate a strategy to address this problem. The demand for manpower has to be accompanied by systems to screen for unsuitable candidates. The reality is that there have been, there are, and there will continue to be asthmatics in the military.
Historically, there has often been a blanket policy of excluding asthmatics altogether. In some nations, even a vague history of childhood asthma would exclude a potential enlistee. This is despite the evidence that two-thirds of childhood asthmatics will be relatively asymptomatic in adulthood (2). One problem is that great weight is placed on the history given by the enlistee, which is not always accurate. Given the uncertainty, there is a role for a structured screening program with the aim of differentiating asthmatics from non-asthmatics, identifying high-risk asthmatics, and possibly selecting well-controlled asthmatics who can perform their roles safely and adequately.
There is published evidence regarding employment of asthmatics and the use of a screening process in enlistment. In a British Army study, the introduction of structured screening led to a reduction in rate of discharge from 50 per year in 1985 to 34 per year in 1994 (3). An U.S. Marine Corp and Navy (USMC/USN) cohort study showed similar findings (4). In both studies, the screening process comprised several layers: a detailed history, physical examination, spirometrie test (including bronchoprovocation test) and exercise challenge testing.
In contrast, attrition rates were higher when structured screening was not utilized (5, 6). The authors of two British Army studies concluded that between 68% and 80% of recruits could have been identified prior to enlistment if a screening exercise test had been done (5,6).
It seems plausible that some well-controlled asthmatics can function well, especially in vocations that do not demand a high level of physical fitness. So, how do asthmatics perform after enlistment? Case control studies suggest that asthma-related discharges were not significantly higher compared to the general recruit pool, provided risk- stratification was in place. With effect from 1995, the U.S. Department of Defense disqualified individuals who had a history of asthma from entering the military. However, exceptions were made in order to enlarge the potential pool of recruits. Some individuals were allowed to enter active duty after being granted waivers (7). Waivers were granted if individuals had been asymptomatic since the age of 12 years, had successful participation in high school athletics (without asthma symptoms) and were highly motivated. The rate of all-cause discharge at 3 years for asthmatics was 22.0%. This was in fact lower than that of the control group (24.6%), though this was not statistically significant.
Although asthma-related discharges or hospitalizations were higher in the cases compared to the controls (4.3% vs. 0.3%), the differences were not felt to be major. Indeed, the discharges generally occurred early in the enlistee's military career, and most of the discharges were within the first 100 days after commencement of basic training. In the British Army, asthma led to an estimated 29 discharges /100,000 total personnel per year, which works out to be just 1 in 3400 servicemen per year (5).
Review of the literature on Exercise-induced bronchoconstriction (EIB) is contradictory. Overall, EIB prevalence is as high as 29% in personnel with a history of childhood asthma (8). In a British Army retrospective study, EIB was a significant problem. Sixty percent of asthmatic servicemen attending the Army Chest Centre had experienced exercise induced symptoms and subsequently failed fitness tests (9). Several factors could account for the British Army finding. Firstly, assessment of potential recruits might have been inadequate. Secondly, this group was studied in the 1980s when aggressive use of preventer inhalers was not the norm. However, a prospective U.S. Army study had very different conclusion. Exercise induced bronchoconstriction did not hinder physical performance during basic training. They also found that peak oxygen uptake levels in subjects with EIB at the beginning and at the end of training were neither clinically nor statistically different from those of unaffected subjects (10).
Recruiting asthmatics raises safety issues. Although mortality appears low, it is of prime concern. Deaths from asthma were uncommon at the USMCA/USN recruit training centre at San Diego. They reported 0.23 asthma deaths per year (11). Data from the British Army was similar, and it was found to be 0.25 deaths per year (5). The Israeli Army which comprises of both conscripts and volunteers reported 0.43 deaths per year amongst their entire strength (12). However these studies should be interpreted with caution, as important factors were not reflected in these retrospective series. First of all, ascribing the cause of death as asthma is difficult even with an autopsy. Secondly, sudden fatal asthma is not common, as symptoms develop over days (13). Yet, it is not known if these deaths occurred in only moderate-to-severe asthmatics, and whether management was optimal, and lastly, if remoteness was an obstacle to medical attention. Thirdly, these studies give us a snapshot of management and mortality rates of asthma two to three decades ago. With better asthma stratification, medication and management, mortality has been in decline in developed healthcare systems (1).
Finally, what is the effect of environmental hazards on asthmatics? There is very little data on this aspect. Two studies of the 1991 Gulf War have shown an association between oil fire smoke and dust storm exposure with respiratory symptoms, but a causal association could not be established (14,15).
In conclusion, we believe that mild asthmatics (and those with mild EIB) can serve in the Armed Forces. However, a structured pre-enlistment screening process should be put in place. This must be capable of identifying high-risk individuals who should be excluded. It also has to stratify risk in milder asthmatics. In addition, Armed Forces should devote resources to educate and monitor asthmatics, as well as optimize treatment after enlistment. Management should incorporate treatment in accordance with the latest guidelines, in which the use of preventer medication such as inhaled corticosteroids is the cornerstone. As for EIB, a Cochrane meta-analysis suggests that regular inhaled corticosteroids for at least 4 weeks are effective in achieving control (16).
Asthma in the Armed Forces is difficult, complex but important aspect of military medicine. There are still many unanswered questions. We need to know which screening tests are most effective. We also have to establish that treatment according to guidelines is as effective in military personnel as it is in the general population. Lastly, what are the effects of environmental and occupational exposure amongst military asthmatics? These issues merit greater attention. We appeal for, and eagerly await further high quality studies.
© 2008 Association of Military Surgeons of the United States Provided by ProQuest LLC. All Rights Reserved.
Source: Military Medicine