Increased Cardiac Death or Decreased Motor Vehicle Accidents?

To the Editor: It was with great interest that we read the article by Madelyn S. Gould, Ph.D., M.P.H., et al. (1), published in the September 2009 issue of the Journal. In a case-control study, the authors arrived at the conclusion that there may be an association between the use of prescribed stimulants and an increased risk of sudden cardiac death. The comparison they used to establish this association was a group of youths who perished in motor vehicle accidents. The authors justified this decision by citing evidence that stimulant users were not likely to be overrepresented within this group.

In finding a higher percentage of stimulant users in the cardiac death group compared with the percentage of stimulant users in the motor vehicle victim group, Dr. Gould et al. made the interpretation that stimulants are likely to increase the risk of cardiac death. However, there is an alternative interpretation that deserves consideration and that, perhaps, has more support in the recent literature. There is a burgeoning interest among clinicians and researchers regarding the effect of attention deficit hyperactivity disorder (ADHD) on driving behavior. The evidence is strong that ADHD is associated with an increased risk of motor vehicle accidents (2) and that stimulants significantly attenuate this risk (2, 3). Thus, it may not be that stimulants were overrepresented in the cardiac death group. It may just appear so because they actually lower the risk of motor vehicle accidents in adolescents and young adults with ADHD and therefore were underrepresented in the comparator group.

This study has attracted significant media attention and has already affected our clinical practice in the short time since its publication. We hope that it will not result in hasty conclusions, driving (quite literally) patients toward the risks of untreated ADHD out of a possibly unfounded fear of treatment. In our view, the tiny risk of cardiac complications from stimulant treatment of a high-risk condition such as ADHD is more than outweighed by the benefits accrued in fewer motor vehicle accidents.