Young and middle-aged adults who are prescribed ADHD (attention deficit/hyperactivity disorder) drugs do not have a higher chance of developing serious cardiovascular events, such as sudden cardiac death, heart attack or stroke, researchers from Kaiser Permanente Northern California, Oakland, reported in JAMA (Journal of the American Medical Association).
The authors explained that there had been concerns regarding the cardiovascular consequences of taking ADHD medications. This is because they can raise the patient's heart rate and blood pressure.
However, this latest study, involving 150,359 adults with ADHD, found no higher risk of having a cardiovascular event in people taking ADHD medications compared to those who don't. All the adults were young to middle-aged.
The findings of this study are being published ahead of schedule because of their public health importance.
The authors explained:
"Between 2001 and 2010, use of medications labeled for treatment of ADHD increased even more rapidly in adults than in children. According to a 2006 U.S. Food and Drug Administration (FDA) advisory committee briefing on the safety of ADHD medications, more than 1.5 million U.S. adults were taking stimulants in 2005, and adults received approximately 32 percent of all issued prescriptions.
Placebo-controlled studies in children and adults indicate that stimulants and atomoxetine [a medication used to treat ADHD] elevate systolic blood pressure levels by approximately 2 to 5 mm Hg and diastolic blood pressure levels by 1 to 3 mm Hg and also lead to increases in heart rate. Although these effects would be expected to slightly increase risk for myocardial infarction [MI; heart attack], sudden cardiac death (SCD), and stroke, clinical trials have not been large enough to assess risk of these events."
Laurel A. Habel, Ph.D., and team set out to determine whether taking ADHD medications during adulthood might be linked to a higher risk of stroke, heart attack or sudden cardiac death (SCD). They gathered data from four computerized health records at four different sites - the earliest site started in 1986, they all ended in 2005. They also used data from a 2007 survey.
All the study participants were aged from 25 to 64 years, who had been taking various ADHD medications which included amphetamine, atomoxetine, or methylphenidate. They matched each ADHD medication user to two non-users in each study site, by sex, birth date, and calendar year. In total, including users and non-users, the study looked at 443,198 individuals.
They reported a total of 1,357 heart attacks, 296 sudden cardiac deaths, and 575 strokes during follow-up.
After examining the data and analyzing them, they found no statistically significant difference in risk between the users and non-users of ADHD medications for the three serious cardiovascular events.
The researchers wrote:
"We also found little support for an increased risk for any specific medication or with longer duration of current use. Results were similar when users were restricted to new users. Rate ratios did not appear to be influenced by prior cardiovascular disease or by prior non-ADHD psychiatric conditions. They also were similar across age groups.
As expected, event rates were substantially higher in the Medicaid population; however, the rate ratio for current use was similar to that in other sites."
Risk of cardiovascular events were no different for one-off, medium and short term users, during their period of taking their medications and for periods over 12 months after discontinuing. There was a similar or very slightly increased risk in new users compared to non-users.
The authors emphasized that they could not rule out a modest rise in serious cardiovascular events, because of some limitations in the study, which did not have full information on a number of factors which could have influenced the results, as well as other factors associated with ADHD drug usage.
Accompanying Editorial in the same journalPhilip Shaw, M.D., Ph.D., who used to work at the NIMH (National Institute of Mental Health) and is now with the Human Genome Research Institute, said the study's findings have raised a number of clinically important issues:
"First, the findings support the final decision by the FDA in 2006 not to place a black box warning of serious cardiovascular events on ADHD medications for all children and adults but to pursue further research. The findings, however, do not directly inform the current black box warning for psychostimulants, which is confined to patients with structural heart lesions.
The study focused on very rare events, which prevented examination of specific subgroups such as individuals with cardiac disease. Joint care by cardiologists and other physicians remains necessary for these individuals.
In addition, the study provides no evidence to support routine obtaining of electrocardiograms before starting treatment, certainly insofar as this recommendation was driven by concerns about serious cardiovascular events."
Written by Christian Nordqvist