AARHUS, Denmark, July 3 -- Epilepsy was associated with a three-fold increase in risk for suicide and the risk was even greater in patients with psychiatric conditions who were newly diagnosed with the neurologic disorder.
During the six months following diagnosis of epilepsy in a patient with a history of psychiatric disease there was a 29-fold increase in risk of suicide (OR 29.2, 95% CI 16.4-51.9, P <0.0001), according to findings published online today by Lancet Neurology.
Even among those with longstanding epilepsy, psychiatric comorbidity was associated with a significantly higher risk of suicide (RR 13.7, 95% CI 11.8-16.0 P <0.0001).
Jakob Christensen, M.D., of Aarhus University Hospital, and colleagues based their findings on an analysis of death certificates of 21,169 suicides and 423,128 controls.
They found 492 individuals with epilepsy who committed suicide (2.32%) versus 3,140 (0.74%) of the controls for a rate ratio of 3.17 (95% CI 2.88-3.50 P <0.0001).
The suicide cases were culled from the Cause of Death Register in Denmark and represented suicides from 1981 through 1997. Each suicide was matched by sex, birth year, and calendar date of death to a maximum of 20 controls.
When persons with a history of psychiatric disorders were eliminated and the data adjusted for socioeconomic confounders, epilepsy remained significantly associated with suicide (RR 1.99, 95% CI 1.71-2.32 P <0.0001).
Michael R. Sperling, M.D., professor of neurology and director of the Jefferson Comprehensive Epilepsy Center in Philadelphia, said the Danish study was "frankly confirmatory of an extensive literature known for many decades." Dr. Sperling was not involved in the study.
Persons with epilepsy, Dr. Sperling said, "are also more likely to experience depression and, particularly when the seizures are uncontrolled, suicides are significantly higher."
But epilepsy is associated with higher all-cause mortality, he said, and although suicide is more common among persons with epilepsy, it is "number five or six on the list [of leading causes of death], not number one."
The most common cause of death associated with epilepsy, said Dr. Sperling, is "unexplained death in epilepsy, which is responsible for 15% to 50% of the excess deaths in these patients. Typically, these patients are found dead in their beds with no apparent cause of death."
Cardiovascular mortality and cancer mortality is also higher among persons with epilepsy, according to Dr. Sperling.
Noting that Christensen et al reported that the risk of suicide was greatest during the six months following an epilepsy diagnosis (overall RR 5.35, 95% CI 3.43-8.33, P <0.0001), Dr. Sperling noted that that may raise more questions than it answers.
"The trouble is that epilepsy is a comorbidity. Why does someone have a recent diagnosis of epilepsy? Recent brain injury, stroke, a brain tumor, so it is always more than just epilepsy," Dr. Sperling said. Any one of those comorbidities could trigger depression that could be a factor in suicide, he said.
On a positive note, Dr. Christensen wrote that "the risk of suicide declined with the duration of epilepsy, which is in keeping with previous studies."
Moreover, the high risk observed within six months of diagnosis, decreased by 12 months. "Improvement in epilepsy care, introduction of new drugs with fewer side-effects, and reduced use of barbiturates are possible explanations for this declining time-trend," he wrote.
The study was funded by the Research Institute of Aarhus University Hospital, the Stanley Research Institute, and the Danish Medical Research Council. Drs. Christensen and Sperling reported no conflict of interest. Primary source: The Lancet NeurologySource reference: Christensen, J "Epilepsy and risk of suicide: a population-based case-control study" Lancet Neurology Published Online July 3, 2007 DOI:10.1016/S1474-4422(07)70175-8
