FRIDAY, April 17 (HealthDay News) -- About half of those who commit suicide have been diagnosed with a mental disorder.

But fewer than 10 percent of their death certificates list mental disorder as a contributing factor, a new study shows.

Incomplete death certificates make it more difficult for health-care policymakers to create prevention strategies, said lead researcher Ian Rockett, a professor of epidemiology and associate chairman of the West Virginia University Department of Community Medicine.

"Death certificates are vital to an understanding of suicide, because they provide frontline data in terms of suicide surveillance," Rockett said. "We need detailed and accurate information to help get our high suicide rates down. … We can't track this when reporting is casual, sloppy or nonexistent."

The study was published in the online British medical journal BMC Psychiatry.

Suicide is the 11th leading cause of death in the United States, according to the National Institute of Mental Heath. Estimates are that 25 people attempt suicide for every one who carries out the act. Suicide outranks homicide as a cause of death.

Incomplete death certificates were the most common among blacks and Hispanics, the study found.

Researchers analyzed data from more than 140,000 death certificates listing suicide from 1999 to 2003 that were released by the National Center for Health Statistics.

They found blacks and Hispanics are much less likely to have depression or other health problems recorded on their death certificates. The gap is largest among males, with white males twice as likely as their minority counterparts to have health problems at the time of their death listed.

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