In a followup study to a highly publicized 2008 report that demonstrated that antidepressant drug trials were selectively published, exaggerating the drugs’ effectiveness, researchers at Oregon Health & Science University (OHSU) found similar concerns exist, though to a somewhat lesser extent, with antipsychotic drugs.
The researchers reached these conclusions by reviewing 24 FDA-registered premarketing trials for eight second-generation antipsychotics: aripiprazole (Abilify), iloperidone (Fanapt), olanzapine (Zyprexa), paliperidone (Invega), quetiapine (Seroquel), risperidone (Risperdal), risperidone long-acting injection (Consta), and ziprasidone (Geodon). They then compared the results in the FDA’s review documents to the results presented in medical journals.
The researchers found that four premarketing trials submitted to the FDA — which yielded unflattering results — remained unpublished. Three showed the new antipsychotic drugs had no significant advantage over a placebo. In the fourth, the drug was superior to a placebo, but it was significantly inferior to a much less expensive competing drug, the researchers note.
In the published trials, there was some evidence that the journal articles over-emphasized efficacy of the new drug, the researchers noted. For example, an FDA review revealed that one of the newer drugs, iloperidone (Fanapt), was statistically inferior to three different competing drugs, but this information was not mentioned in the corresponding journal articles, the OHSU researchers found.
On the other hand, when the researchers used meta-analysis to combine trial data and compare all eight drugs to a placebo, they found that publication bias had little impact on the drugs’ overall apparent efficacy. This stood in contrast to the researchers’ previous study on antidepressants, for which publication bias had a much more substantial impact.
“When you compare between drug classes and use FDA data, it’s clear that, overall, antipsychotics are more effective than antidepressants. But when you rely on the data in medical journals, the difference between these two drug classes is obscured,” said Erick Turner, M.D., an assistant professor in the Department of Psychiatry and the Department of Pharmacology in the OHSU School of Medicine. “Publication bias can blur distinctions between effective and ineffective drugs. With further studies investigating publication bias in other drug classes, a more accurate evidence base can emerge.”