"The post hoc analyses were exploratory and, as such, carry concerns about spurious findings from multiple comparisons," they wrote. "Thus, the results should be interpreted as preliminary."
"Dosages of the medications in the double-blind condition may have advantaged some medications (e.g., olanzapine(Drug information on olanzapine)) and not others (e.g., quetiapine and ziprasidone(Drug information on ziprasidone))," they added.
It is not surprising, Dr. Tamminga and colleagues said, that many patients were already on a drug that suited them better than others, so that switching worsened their condition.
Primary source: American Journal of Psychiatry
Source reference: Essock SM et al. "Effectiveness of Switching Antipsychotic Medications." Am J Psychiatry 2006; 163:2090-2095.