Hearst N, Newman T B, Hulley S B
N Engl J Med. 1986 Mar 6;314(10):620-4. doi: 10.1056/NEJM198603063141005.
To study the effect of military service during the Vietnam era on subsequent mortality, we analyzed a randomized natural experiment, the military draft lottery of 1970 to 1972. Between 1974 and 1983, there were 14,145 deaths among California and Pennsylvania men whose dates of birth were in the years for which the draft lottery was held. The group of men with birth dates that made them eligible for the draft had a higher mortality rate than the group with birth dates that exempted them from the draft: suicide was increased by 13 percent (P = 0.005 by two-tailed test), death from motor-vehicle accidents by 8 percent (P = 0.03), and total mortality by 4 percent (P = 0.03). Only 26 percent of the men who were eligible for the draft actually entered the military. If military service (rather than draft eligibility) was the actual risk factor, suicide and death from motor-vehicle accidents would have to have been increased by 86 percent and 53 percent among men who served in the military, to produce the increased risk that we observed among all draft-eligible men. A separate analysis that compared the causes of death in veterans and nonveterans yielded similar estimates: veterans were 65 percent and 49 percent more likely to die from suicide and motor-vehicle accidents, respectively. We conclude that the most likely explanation for these findings is that military service during the Vietnam War caused an increase in subsequent deaths from suicide and motor-vehicle accidents.
为研究越南战争时期服兵役对后续死亡率的影响，我们分析了一项随机自然实验，即1970年至1972年的征兵抽签。1974年至1983年期间，加利福尼亚州和宾夕法尼亚州出生日期在征兵抽签年份的男性中有14145人死亡。出生日期使他们有资格应征入伍的男性群体的死亡率高于出生日期使他们免服兵役的男性群体：自杀率增加了13%（双侧检验P = 0.005），机动车事故死亡率增加了8%（P = 0.03），总死亡率增加了4%（P = 0.03）。只有26%有资格应征入伍的男性实际进入了军队。如果服兵役（而非应征资格）是真正的风险因素，那么在服兵役的男性中，自杀率和机动车事故死亡率将不得不分别增加86%和53%，才能产生我们在所有有应征资格的男性中观察到的风险增加。一项比较退伍军人和非退伍军人死因的单独分析得出了类似的估计结果：退伍军人死于自杀和机动车事故的可能性分别高出65%和49%。我们得出结论，对这些发现最有可能的解释是，越南战争期间的服兵役导致了后续自杀和机动车事故死亡人数的增加。
