Extended placebo-controlled clinical trials in schizophrenia research pose an ethical challenge. This study examines factors that have implications for the design and duration of placebo-controlled acute efficacy trials: Does early response discriminate active drug (AD) from placebo, and are the early differences sustained over time? A post hoc pooled analysis of 2 randomized 6-week double-blind clinical trials was performed comparing patients with schizophrenia treated with placebo or low-dose olanzapine (1 mg/d; placebo/low dose [PBO] group, n = 170) to patients treated with a 10- to 20-mg/d dose of haloperidol or medium- to high-dose olanzapine (7.5 to 17.5 mg/d; AD group, n = 252). Mixed-model repeated-measure analysis tested for group differences. Power analysis was undertaken to compare study designs with shorter durations. At 2 weeks, the mean reduction in the Brief Psychiatric Rating Scale total score was significantly greater for the AD group (-10.1) compared with the PBO group (-4.1; P < 0.001); this difference was sustained until the study ended (6 weeks). A higher proportion of early treatment responders were observed for the AD group (52%) compared with the PBO group (29%; P < 0.001). Early nonresponse to placebo or drug was predictive of subsequent nonresponse (negative predictive value: PBO = 95%, AD = 84%). Power analysis indicates that the placebo-drug differences are robust at 2 weeks. Treatment responders from the AD and the PBO groups followed a similar response path. Early response to antipsychotic treatment discriminated AD from placebo. Reducing placebo-controlled clinical trials from 6 weeks to 2 to 4 weeks was found to be a viable option for efficacy identification in acutely ill patients.
The number-needed-to-treat (NNT) or the number-needed-to-harm (NNH) analysis was performed on olanzapine and comparators for all known controlled clinical studies of olanzapine for bipolar maintenance treatment or relapse prevention to assess safety and efficacy. Studies compared olanzapine (n = 225) and placebo (n = 136) for 12 months, olanzapine (n = 217) and lithium (n = 214) for 12 months, and olanzapine plus lithium or valproate (n = 72) and placebo plus lithium or valproate (n = 64) for 18 months. For prevention of all-cause treatment discontinuation, the NNT was 7 to 8. For 9 of 11 efficacy and disposition measures examined, beneficial outcomes were more common with olanzapine than placebo. Beneficial outcomes were more common with olanzapine than lithium for 7 measures and more common for olanzapine plus lithium or valproate than placebo plus lithium or valproate for 1 measure. The NNHs of 5 to 8 for a weight gain of 7% or higher and 10 to 11 for the increase in body mass index category to overweight or obese during maintenance treatment indicated that these outcomes were more common for olanzapine or olanzapine plus mood stabilizers than for the comparators. All efficacy and disposition measures showing significant differences between groups for 12 to 18 months have NNTs favoring olanzapine or olanzapine plus lithium or valproate over placebo, lithium, or placebo plus lithium or valproate. However, the NNHs favor these comparators for avoidance of weight gain and of increase in body mass index category to overweight or obese. Clinicians should consider these and other potential benefits and risks in using maintenance treatments for patients with a bipolar disorder.
To better understand sexual dysfunction in patients with schizophrenia and its associations with prolactin and reproductive hormones.
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