Mixed Messages on ADHD Drugs Side Effects
Last week, an FDA advisory committee voted to recommend adding ‘black box’ safety warnings to ADHD drugs. This week, the director of the FDA’s division of psychiatry products says it would be unusual for the agency to issue a ‘black box’ warning based on such thin evidence. A second FDA committee, which focuses on pediatrics, will consider the drugs’ safety next month.
Twenty-five people died suddenly and another 54 suffered serious cardiovascular problems after taking drugs to treat attention deficit hyperactivity disorder between 1999 and 2003, according to a report from the US government’s Food and Drug Administration (“FDA Reports on Deaths from ADHD Drugs”). Last week, an FDA advisory committee voted to recommend adding ‘black box’ safety warnings to ADHD drugs.
Now, however, it appears the FDA is back-pedalling on the issue, with the director of the agency’s division of psychiatry products saying it would be unusual for the agency to issue a ‘black box’ warning based on such thin evidence.
In fact, in an article carried by APA’s PsycPort, he claims that the reported number of sudden deaths in patients taking stimulants is actually lower than the figure that experts would expect to see among people who aren’t taking the drugs.
Hold on! Last week, the only question appeared to be whether ADHD drugs were in fact responsible for causing serious cardiovascular problems (including 25 deaths); now, the question appears to be whether those cardiovascular problems are actually occurring at a lower incidence than one would expect among those not taking the drugs. I would hope it’s unlikely that everyone just forgot to normalize the original data relative to those not taking ADHD drugs.
This is basic statistics! Either the incidence of sudden deaths is significantly higher for patients taking ADHD drugs, or it is lower, or the difference is not statistically significant. In the absence of some comparison to the expected number of cardiac events across a relevant population not taking ADHD medications, the absolute number of cardiovascular problems or deaths among those who are taking the medications is statistically meaningless.
There only seem to me to be two possibilities here: either the original advisory committee deliberations were significantly ill-informed about the data, or the agency’s director of psychiatry products is ill-informed. How can they both be well-informed, if they apparently disagree about whether use of the medications is even correlated with a higher incidence of cardiac events, quite apart from the real question of whether the medications are actually causal contributors to that higher incidence?
ADHD sufferers and their families would probably like some clear and specific guidance from the agency on this issue, not statistical obfuscation.
