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ADHD medication and cardiovascular risk

In ADHD, ADHD Adult, ADHD child/adolescent, ADHD stimulant treatment, Medication, Psychiatry, Psychopharmacology on Wednesday, 26 September 2012 at 07:20

i believe many people may hold some misconceptions related to stimulant medication in treating ADHD.  in fact, i have a personal story related to that.  a friend of mine needed to go to the emergency room for a cut that needed stitches.  while in triage, the nurse took her blood pressure and it was quite elevated.  the nurse questioned her about her bp and asked if she was diagnosed with high blood pressure (this person is an avid athlete and has never had issues with high bp).  once the nurse saw on her intake form that she took 10mg. of adderall a day for adult ADHD, she told my friend that that medicine was “toxic” and the she needed to stop it “right away” and go to her doctor immediately for a cardiac assessment.  she repeatedly stated that the adderall she was taking was going to do her harm and she MUST stop taking it right away!  my friend was somewhat startled at the nurse’s vehement opinions regarding the adderall.  what i do know is that, when i am hurt or in a tense situation (i.e. the emergency room and in pain), my blood pressure might temporarily go up.  i also know that i DO NOT have high blood pressure.  no mention of being anxious or in pain was made in relation to my friend’s high bp at that time.  on a side note, once my friend was out of the ER and we had gone to the pharmacy to get a prescription, she took it again and it was well within the normal range, showing she was just anxious/worried/in pain and her higher bp was a residual effect of that.  but…this does illustrate that there are times people believe that something is fact because of popular opinion, their own biases, etc., even when the literature may not support their belief/s.  so, in light of that, i wanted to share a post on stimulant medication and cardiovascular risk.  as you can see, it is not as clear-cut as our opinionated nurse thought it was.

ADHD Medications in Adults Yield Mixed Cardiovascular Risk Results

Deborah Brauser & Hien T. Nghiem, MD

In the United States, roughly 1.5 million adults use medications for attention-deficit/hyperactivity disorder (ADHD). These medications include amphetamines, atomoxetine, and methylphenidate. ADHD medications are known to increase both blood pressure (< 5 mm Hg) and heart rate (< 7 bpm). Given these effects, there are concerns regarding serious cardiovascular events related to taking ADHD medications.

The aim of this study by Hennessy and colleagues was to determine whether use of methylphenidate in adults is associated with elevated rates of serious cardiovascular events compared with rates in nonusers.

Study Synopsis and Perspective

Although adults prescribed the ADHD medication methylphenidate may be at increased risk for adverse cardiovascular events, this association may not be causal, new research suggests.

In a cohort study of almost 220,000 individuals, new users of methylphenidate had almost twice the risk for sudden death or ventricular arrhythmia than age-matched control participants had. They also had a significantly higher risk for all-cause death.

However, the medication dosage “was inversely associated with risk,” meaning it lacked a dose-response relationship, report the investigators.

“We were surprised by the risk findings. But the inverse associations leads us to be somewhat skeptical,” coinvestigator Sean Hennessy, PharmD, PhD, associate professor of epidemiology and pharmacology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, told Medscape Medical News.

“Ordinarily, if a drug increases the risk of adverse outcomes, that increase is going to be dose-dependent. We didn’t see that, and in fact, found an inverse relationship for death and other outcomes,” he explained.

Dr. Hennessy said that this could be due to “frail, elderly patients who have other things going on” and who are prescribed low-dose methylphenidate.

“Maybe baseline differences in those patients that aren’t captured in the medical claims data are responsible for the elevated risk of adverse outcomes we were seeing rather than it being a causal effect of the methylphenidate itself,” he opined.

“So I would say to wait for these findings to be replicated and clarified in other research before they are acted on clinically.”

The study is published in the February issue of the American Journal of Psychiatry.

Mixed Findings

According to the investigators, methylphenidate and other ADHD medications are used by almost 1.5 million adults in the United States — even though these medications have been shown to raise blood pressure and heart rate.

“Given these effects, case reports of sudden death, stroke, and myocardial infarction have led to regulatory and public concern about the cardiovascular safety of these drugs,” write the researchers.

However, in May 2011, and reported by Medscape Medical News at that time, the same group of researchers published a study in Pediatrics that showed no increased risk for cardiovascular events in children treated with ADHD medications.

In addition, researchers from Kaiser Permanente Northern California published a study in December 2011 in the Journal of the American Medical Association that examined risks in adults younger than age 65 years who were taking methylphenidate, amphetamine, atomoxetine, or pemoline.

The combined group of ADHD medication users showed no increased risk for serious cardiovascular events, including myocardial infarction, sudden cardiac death, or stroke, compared with the group of nonusers.

For this analysis, investigators examined records from Medicaid and commercial databases, representing 19 states, for adults in a broader age range. Included were 43,999 new users of methylphenidate and 175,955 individuals who did not use methylphenidate, amphetamines, or atomoxetine (for both groups, 55.4% were women).

In each group, 67.3% of the participants were between the ages of 18 and 47 years, 23.2% were between the ages of 48 and 64 years, and 9.5% were aged 65 years or older.

Primary cardiac events assessed included sudden death or ventricular arrhythmia, myocardial infarction, stroke, and a combination of stroke/myocardial infarction. All-cause death was a secondary measure.

Unexpected Results

Results showed that the adjusted hazard ratio (HR) for sudden death/ventricular arrhythmia for the methylphenidate users compared with the nonusers was 1.84 (95% confidence interval [CI], 1.33 – 2.55). For all-cause death, the HR was 1.74 (95% CI, 1.60 – 1.89).

Adjusted HRs for myocardial infarction and stroke (alone or in combination) were not statistically different between the 2 treatment groups.

For the participants who experienced a cardiovascular event, the median treatment dosage was 20 mg/day. No significant association was found for sudden death/ventricular arrhythmia between the patients who took more or less than 20 mg/day of methylphenidate.

“However, there were unexpected inverse associations” between high methylphenidate dosage and stroke, myocardial infarction, stroke/myocardial infarction, and all-cause death compared with low dosage, report the researchers. They add that this lack of a dose-response association discredits a causal relationship.

“Furthermore, the inverse relationships…may suggest that lower dosages were prescribed to the frailest patients, who might have had a greater risk of all-cause death and sudden death — that is, the results may have been affected by unmeasured confounding,” write the investigators.

Other limitations cited included the fact that the study was not randomized and that administrative databases do not include potential confounders such as smoking, blood pressure, substance use, and exercise use/nonuse.

Dr. Hennessy reported that the investigators also assessed cardiovascular risks in their study participants who were also taking amphetamines or atomoxetine. They will be publishing those results soon.

Findings “Generally Reassuring”

Christopher J. Kratochvil, MD, from the University of Nebraska Medical Center in Omaha, writes in an accompanying editorial that this and other studies are “generally reassuring and demonstrate movement in the right direction, with systematic retrospective analyses better informing us of issues related to cardiovascular safety with ADHD pharmacotherapy.”

“While gaps persist in the methodical and comprehensive assessments of the safety of ADHD medications, these studies add valuable information to our already large repository of safety and efficacy data…and better inform the risk-benefit analysis of their use,” writes Dr. Kratochvil, who was not involved with this research.

He adds that establishing a “robust” national electronic health records system containing detailed data elements will also offer considerable help to clinicians.

These large and more accessible databases “will allow us to improve our identification and understanding of rare but serious adverse effects and better address these questions of public health significance,” he concludes.

The study was funded through a sponsored research agreement with Shire Development, Inc., and by a Clinical and Translational Science Award from the National Institutes of Health. The study authors all receive salary support from Shire through their employers. All financial disclosures for the study authors and Dr. Kratochvil are listed in the original article.

Am J Psychiatry. 2012;169:112-114;178-185. Abstract, Editorial

Study Highlights

■This study was a nonrandomized cohort study of new users of methylphenidate based on administrative data from a 5-state Medicaid database (1999-2003) and a 14-state commercial insurance database (2001-2006).

■All new methylphenidate users with at least 180 days of prior enrollment were identified.

■Users were matched on data source, state, sex, and age to as many as 4 comparison participants who did not use methylphenidate, amphetamines, or atomoxetine.

■A total of 43,999 new methylphenidate users were identified and were matched to 175,955 nonusers.

■The main outcome measures were (1) sudden death or ventricular arrhythmia; (2) stroke; (3) myocardial infarction; and (4) a composite endpoint of stroke or myocardial infarction.

■Secondary outcomes included all-cause death and nonsuicide death.

■Results demonstrated that the age-standardized incidence rate per 1000 person-years of sudden death or ventricular arrhythmia was 2.17 (95% CI, 1.63 – 2.83) in methylphenidate users and 0.98 (95% CI, 0.89 – 1.08) in nonusers, for an adjusted HR of 1.84 (95% CI, 1.33 – 2.55).

■Dosage was inversely associated with the risks for stroke, myocardial infarction, stroke/myocardial infarction, and all-cause death.

■Adjusted HRs for stroke, myocardial infarction, and the composite endpoint of stroke or myocardial infarction did not differ statistically from one another.

■For the secondary outcome of all-cause death, methylphenidate demonstrated a positive association (adjusted HR, 1.74; 95% CI, 1.60 – 1.89). Nonsuicide deaths were nearly identical.

■Limitations of this study include the potential for unmeasured confounders (ie, smoking, blood pressure, nonprescribed aspirin use, substance misuse, and level of physical activity) because the study was not randomized.

Clinical Implications

■ADHD medications raise blood pressure by less than 5 mm Hg and heart rate by less than 7 bpm.

■Although initiation of methylphenidate was associated with a 1.8-fold increase in the risk for sudden death or ventricular arrhythmia, the lack of a dose-response relationship suggests that this association may not be a causal one.

Retrieved from: http://www.medscape.org/viewarticle/759069

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