Cardiac Safety of Methylphenidate Versus Amphetamine Salts in the Treatment of ADHD

Abstract

Safety concerns about central nervous system stimulants for the treatment of attention-deficit/hyperactivity disorder (ADHD) include adverse cardiac effects. This study aimed to compare the risk for cardiac events in users of methylphenidate and amphetamine salts. A retrospective cohort design using claims data from the Florida Medicaid fee-for-service program representing a total of 2131953 children and adolescents was used. The analysis included all beneficiaries who were between 3 and 20 years of age, enrolled between July 1994 and June 2004, had at least 1 physician diagnosis of ADHD and were newly started on methylphenidate or amphetamine salts. Each month of follow-up was classified according to stimulant use into current use or former use. We defined cardiac events as first emergency department (ED) visit for cardiac disease or symptoms. Risk between current users of methylphenidate versus amphetamine salts and former users of drugs in these categories was compared by using a time-dependent Cox proportional hazard model that adjusted for differences in gender; race; age; year of the index date; disability; congenital anomalies; history of circulatory disease; history of hospital admission; and use of antidepressants, antipsychotics, and bronchodilators. A total of 456 youth visited the ED for cardiac reasons during 52783 years of follow-up. After adjustment for differences in covariates, the risk for cardiac ED visits was similar among current users of methylphenidate or amphetamines. Periods of former use had a similar risk between youth with an exposure history to methylphenidate or amphetamine. Exposure to methylphenidate and amphetamines salts showed similar risk for cardiac ED visits. Additional population-based studies that address manifestation of serious heart disease, especially after long-term use, dosage comparisons, and interactions with preexisting cardiac risk factors are needed to inform psychiatric treatment decisions.