No link between ADHD meds, increased CV events

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There appears to be no differences in cardiovascular (CV) events among children and teens taking attention-deficit hyperactivity disorder medications and those not taking the medications, results from a large observational study indicate.

“For kids who will benefit from ADHD treatment, the potential risk of a [CV] event should not dissuade parents or caregivers from giving a child or adolescent these drugs,” study researcher Sean Hennessy, PharmD, PhD, an associate professor of epidemiology at the University of Pennsylvania School of Medicine in Philadelphia, said in a press release.

ADHD medications are known to increase systolic and diastolic BP, according to background information in the article, and case reports of sudden death among children and adolescents taking these medications have raised concern about increased risk for CV events. However, previous clinical trials have yielded mixed results.

To further investigate, Hennessey and colleagues assessed the risk for sudden death, myocardial infarction and stroke among a cohort of 241,417 patients aged 3 to 17 years who were prescribed ADHD medications and compared incident rates to 965,668 patients of the same age and gender who were not on the medications.  

Study data were taken from two administrative databases — a Medicaid database and a HealthCore Integrated Research Database — and included children who had a prescription for an ADHD medication, including amphetamine, atomoxetine, or methylphenidate. Results were published online ahead of the June Pediatrics issue.

There were 71 hospital and 212 emergency department claims for sudden death or ventricular arrhythmia, during the follow up period.

Among both ADHD medication users and nonusers, there were 142 hospital claims for stroke and 25 hospital claims for MI. Only about half of these events could be validated from medical records, according to the researchers.

They found that rates of validated cases of sudden death or ventricular arrhythmia were similar between both groups (0.06 vs. 0.04 per 10,000 person-years; HR 1.60, 95% CI: 0.19 to 13.60). Results from a previously published study indicated an incidence rate of 0.33 per 10,000 individuals ages 1 to 20 per year for sudden death and ventricular arrhythmia.

“If we assume that the positive predictive value in the unavailable records in our study was the same as those for whom records were obtained, the incidence rate of sudden death or ventricular arrhythmia in our study would have been 0.21 to 0.28 per 10,000 person-years in nonusers, which is very similar to these previous findings," the researchers wrote.

Furthermore, ADHD medication users also had lower all-cause mortality rates compared with nonusers (1.79 versus 3.00 per 10,000 person-years; HR 0.76, 95% CI 0.52 to 1.12), the researchers reported.

Because no incidents of myocardial infarction or stroke occurred in participants prescribed ADHD medication, the researchers were unable to rule out relative increases in the rate of these events with the medication. Only 11 cases of MI and stroke occurred in the non-medication group, indicating a “very low” overall CV incidence rate.

Low retrieval rates of medical records may have reduced the study's statistical power, the researchers warned and added that there was also potential for residual confounding.

Schelleman H. Pediatrics. 2011; 127: 1102-1110.

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