THE HEALTH EFFECTS OF MILITARY SERVICE: EVIDENCE FROM THE VIETNAM DRAFT

I. INTRODUCTION The impact of military service on long-term health is reemerging as a vital policy question as the United States conducts major military operations in Iraq and Afghanistan. Health professionals have raised concerns that significant numbers of the veterans of these conflicts are experiencing psychological and physical health problems. The Department of Veterans Affairs estimates that anywhere from 12 to 20% of servicemen returning from Iraq suffer from posttraumatic stress disorder, which the medical literature suggests can have a long-term adverse effect on an individual's health. In the 2005 fiscal year, the Department of Veterans Affairs spent about 32 billion dollars on medical care for veterans: a substantial liability for the American taxpayer. Thus, understanding the long-term health impacts of military service is important both for allocating treatment resources and for correctly estimating the cost of waging these two wars. Comparing the health of veterans with that of nonveterans may not give us credible estimates of the effect of military service. People voluntarily enlisting in the military differ in their observable characteristics from those who do not. These observable differences between veterans and nonveterans leave us concerned that cross-sectional estimates of the long-term health consequences of military service will be biased by systematic differences in the unobservable characteristics of the two groups. For this reason, we use the draft lottery implemented during the Vietnam War as an instrument for military service. The draft lottery required randomly selected men born between 1944 and 1952 to report for possible induction into the military. We use confidential versions of the 19742004 National Health Interview Surveys (NHIS) (1) to examine the impact of military service on veterans' health. We focus on the 67,608 men who were born between 1950 and 1952 because, as we document, this is the cohort most affected by the Vietnam draft lottery. We begin with a cross-sectional comparison of veterans and nonveterans, which reveals that veterans are in systematically worse health than nonveterans and that these health disparities increase with age. These estimates probably overstate the causal effect of military service because veterans differ systematically from nonveterans on dimensions such as education that are strongly associated with adverse health. When we correct for this problem using draft status to instrument for military service, we find that despite a very strong first-stage relationship between draft eligibility and military service, the 2-stage least squares (2SLS) estimates of the impact of military service on health are fairly imprecise. For most of the outcomes, we examine the confidence intervals from the 2SLS regressions containing both zero and the point estimate from the cross-sectional regression. This paper makes two contributions to the literature. First, unlike the cross-sectional literature on the impact of military service on health, the instrumental variables approach used in this paper provides unbiased estimates. Second, this paper documents that though the Vietnam lottery very significantly increased military service, it led to only a modest increase in combat exposure. (2) In the following section, we discuss the existing literature on veterans' health and on the impact of the Vietnam Era Draft. In Section III, we describe our primary data source, the NHIS. In Section IV, we discuss the research methodology and some of the issues that complicate the use of draft eligibility as an instrument. Section V discusses our results, and Section VI concludes. II. PREVIOUS LITERATURE There is a significant literature documenting the disproportionate prevalence of health problems among military veterans. Hoge et al. (2004) find that mental health problems are common in veterans who served in Iraq and Afghanistan. …