The findings of a new study raise questions about the previously reported link between a new class of antidepressant drugs and an increased risk of suicide. Specifically, the suicide rates in the United States have decreased since the introduction of fluoxetine (Prozac) and other antidepressants in the same class, researchers from the University of California Los Angeles report.

They estimate that more than 30,000 lives have been saved since this new class of antidepressants - selective serotonin reuptake inhibitors (SSRIs) - was introduced.

“Our findings certainly suggest that the introduction of SSRIs has contributed to reduction of suicide rates in the United States,” Dr. Julio Licinio, who is now at the University of Miami, and colleagues commented in a statement. “However, the findings do not preclude the possibility of increased risk of suicide among small populations of individuals,” they added.

The U.S. Food and Drug Administration introduced “black box warnings” on the most popular SSRIs in 2004 after studies in the United States and Britain suggested the drugs might increase the risk of suicide in children and adults.

“Although the current issue concerning antidepressants and suicidality requires further examination, we believe that many more lives have been saved than lost since the advent of these drugs,” the researchers write in their study, published in the Public Library of Science Medicine journal. The effect appears to be strongest among women.

Using data from the Centers for Disease Control and Prevention and the US Census Bureau, Licinio’s team found that the suicide rate did not change in the 15 years before Prozac was introduced in 1988. After this point, the rates declined steadily in the next 14 years, as the number of SSRI prescriptions rose.

Compared with data collected before 1988, the investigators found that there were 33,600 fewer suicides in the period from 1988 to 2002.

The suicide rates ranged from 12.2 to 13.7 per 100,000 people until 1988, and then gradually declined to a low of 10.4 per 100,000 in 2000, Licinio’s team reported. The number of prescriptions written for fluoxetine rose from about 2.5 million in 1988 to more than 33 million in 2002.

“Much of the psychiatric community fears that the absence of treatment may prove more harmful to depressed individuals than the effects of the drugs themselves,” Licinio team noted. “Most people who commit suicide suffer from untreated depression.”

SOURCE: PLoS Medicine, June 2006.