Stimulants used to treat children with attention deficit hyperactivity disorder may cause an increased number of visits to emergency rooms or doctor's offices for cardiac symptoms but deaths or serious heart complications are rare, according to an article in the December issue of Pediatrics.

"Treatment decisions are always a risk-benefit assessment for doctors," said Almut Winterstein, PhD, an assistant professor of pharmacy health care administration at the University of Florida's College of Pharmacy. "We know about the benefits of central nervous system stimulants. There are a lot of advantages to the patient - improved concentration, the improved ability to interact socially - but the risks have been very poorly defined."

Winterstein, a pharmacoepidemiologist, led a team of researchers in pharmacy, pediatric medicine and psychiatry at the University of Florida who analyzed records from 55,000 patients age 3 to 20 years who were undergoing treatment between 1994 and 2004.

The study, which sought to assess the effects of these drugs on the risk for heart disease, relied on the Florida Medicaid database of more than 2 million youth, cross-matched with vital statistics records - the first study of this magnitude in safety research related to the disorder.

Children who used central nervous system stimulants were 20 percent more likely to visit an emergency clinic or doctor's office with cardiac-related symptoms, such as a racing heartbeat, than children who had never used or had discontinued such treatment.

However, the rates of death or hospital admission for serious heart conditions were no different than the national rates among the general population, although the total number of events was too small to allow definite conclusions.

"Methylphenidate and dextroamphetamine have been carefully studied for cardiovascular side effects in children for periods up to three years in extended clinical trials, and the reports indicate minor blood pressure and heart rate changes - which the authors deem clinically insignificant," Daniel Safer, MD, an associate professor in psychiatry and pediatrics at Johns Hopkins University School of Medicine.

In 2006, the U.S. Food and Drug Administration's Drug Safety and Risk Management Advisory Committee recommended a black-box warning regarding the drugs' cardiovascular risks be added to the package insert. However, the FDA's Pediatric Advisory Committee disagreed, saying there was strong scientific evidence the drugs were beneficial, whereas data regarding risks indicated cardiac effects were often mild and could be treated by adjusting the dose or timing of medication.

The current findings raise several important issues that warrant further investigation, Winterstein said. Critical concerns include stimulant safety in populations with cardiac risk factors and in those who use the drugs for several years. The current study found that more than 25 percent of stimulant users also used antidepressant or antipsychotic drugs, which are known to affect the heart and blood pressure as well.

In Safer's practice, most parents whose children were diagnosed with the disorder and prescribed stimulants have been satisfied with the treatment effects.

"In fact," he added, "more parents than previously are requesting such treatment if their child is having serious problems in school."