Rockville, MD - The Food and Drug Administration (FDA) and the Agency for Healthcare Research and Quality (AHRQ) announced they will collaborate on "the most comprehensive study to date" of potential cardiovascular risks associated with the prescription medications used to treat attention deficit/hyperactivity disorder (ADHD) [1].

The study will examine clinical data on about 500 000 children and adults who have taken medications used in ADHD, looking specifically for cardiovascular risks, including MI and stroke.

"Because medications used to treat ADHD can increase heart rate and blood pressure, there are concerns about the drugs' potential to increase cardiac risks," a statement from the FDA notes. "It is also thought that these risks may be different for adults and children, but more evidence is needed about the long-term effects of using ADHD medications."

The planned analysis follows an FDA-sponsored preliminary study that compiled information from large healthcare databases on prescription drug use, inpatient care, outpatient treatment, and health outcomes including death, the statement says. From this work, researchers identified people who took ADHD drugs over a seven-year period ending in 2005.

The study will be coordinated by Vanderbilt University researchers, with principal investigator Dr William D. Cooper, on contract through AHRQ's Effective Health Care Program, and data analysis will be performed at Vanderbilt, Kaiser Permanente of California, the HMO Research Network, and i3 Drug Safety, as well as the FDA and AHRQ.

The analysis will focus on all drugs currently marketed for ADHD and look at risks associated with the drugs as a whole and grouped by class. The results are expected in about two years.

"Case reports have described adverse cardiovascular events in adult and pediatric patients with certain underlying risk factors who receive drug treatment for ADHD, but it is unknown whether or not these events are causally related to treatment," said Dr Gerald Dal Pan, director of the FDA's Office of Surveillance and Epidemiology. "The goal of the study is to develop better information on this question."

"This study highlights one of AHRQ's most important missions: to collect and analyze scientific evidence that will help patients, policymakers, and clinicians make the best possible decisions," said AHRQ director Carolyn M Clancy in the statement.

According to the National Institute of Mental Health, ADHD affects approximately 3% to 5% of school-aged children and about 4% of adults.

Use of ADHD drugs has increased in recent years among both children and adults, the statement added. "A recent AHRQ analysis of medication expenditures found three ADHD drugs—Concerta (methylphenidate hydrochloride [ALZA/McNeil Pediatrics]), Strattera (atomoxetine HCL [Eli Lilly]), and Adderall (mixed salts of a single-entity amphetamine product [Shire US])—ranked among the top five drug prescribed for children ages 17 years and younger," the statement notes, with an estimated $1.3 billion spent in 2004. Adult use is also thought to be increasing.

In February 2007, the FDA directed manufacturers of all drug products approved for ADHD to develop patient medication guides to alert patients to possible adverse cardiovascular and psychiatric events related to treatment. The move came after an FDA review of case reports of serious cardiovascular events including sudden death in subjects with underlying heart problems or defects and reports of stroke and MI in adults with certain risk factors.

They also noted a slight increased risk (about one per 1000) of drug-related psychiatric adverse events such as hearing voices, becoming suspicious for no reason, or becoming manic, even in patients without a previous psychiatric history.