Military draftees who served during the Vietnam war era are as much as 86 percent more likely to die by suicide than their peers who did not serve and as much as 53 percent more likely to die in motor vehicle accidents, a major study reports today.

"We are looking at an expression, a final tragic expression, of the very serious long-term effects that this experience of being in Vietnam had," said Dr. Norman Hearst of the University of California at San Francisco, who coauthored the study published in the New England Journal of Medicine.

While other studies have indicated a high death rate among Vietnam veterans, the California researchers said their research appears to be first to establish a cause-and-effect relationship between military service and subsequent deaths from suicide and motor vehicle accidents.

"They are just as much casualties of the Vietnam war as those who died on the battlefield," Hearst said.

The researchers made their conclusions after examining death records between 1974 and 1983 of 14,145 California and Pennsylvania men involved in the lottery system that determined draftees from 1970 to 1972.

They found that motor vehicle accidents and suicides were slightly higher among those eligible for the draft, with greater increases among those who actually served. Only about one-fourth of those eligible served.

The increased risk of such deaths for individuals is small, but the longterm impact may be great, given the large numbers of people who served during the war, the study said.

While the greatest difference in traffic deaths occurred in the first few years after veterans returned home, the study found that the increased suicide rate has not leveled off.

The study suggests that 1,250 deaths nationwide among those drafted in the early 1970s may be connected to military service during Vietnam as may be "tens of thousands of additional deaths" among draftees earlier in the war, Hearst said.

About 8 million Americans saw military service during the Vietnam era, including about 4 million in Indochina. About 800,000 were in combat. There were nearly 50,000 U.S. battle deaths, according to the Defense Department.

The study did not distinguish between those involved in the Vietnam war and those who served in the military elsewhere during that era.

Hearst said the findings show that those who served during the Vietnam era are "clearly identified" as being at long-term higher risk of dying. "We owe it to these people to do everything we can to help them," he said. The researchers also warned that future decision-makers who may force young men to undergo military service should take into account long-term consequences.

Many Vietnam veterans have reported delayed psychological and physical effects attributed by experts to "posttraumatic stress disorder." Several studies found higher rates of drug and alcohol abuse, depression, marital problems, aggressive behavior, arrests and a higher death rate among this group. Some critics have suggested, however, that the problems may have reflected differences among those who served rather than effects of war.

Hearst said his study scientifically validates the stress disorder seen in Vietnam veterans by taking advantage of a "very large randomized natural experiment" -- use of the lottery system based solely on birth dates.

Because those who would or would not be drafted by lottery were so similar, except for draft status, subsequent differences in their death rates were attributed to the fact that some were drafted.

The study does not pinpoint specific causes of the increased death rates. But Hearst and his colleagues cited social and economic difficulties of returning to civilian life, increased susceptibility to mental illness and physical handicaps as possible factors.

Driving while intoxicated may have contributed to the traffic deaths, while veterans' greater familiarity with firearms might have increased the likelihood that they would commit suicide with a gun, the reseachers said.

An editorial in the journal by New York physician Lawrence Kolb called the study an "ingenious" confirmation of chronic impairment suffered by Vietnam veterans. He urged doctors to pay added attention to symptoms that may indicate continuing problems.