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Acta Psychiatr Scand. 2019 Feb;139(2):108-116. doi: 10.1111/acps.12960. Epub 2018 Sep 9.

Placebo effects in adult and adolescent patients with schizophrenia: combined analysis of nine RCTs.

Author information

1
Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan.
2
Department of Psychiatry, Psychotherapy and Psychosomatics, Medical University Innsbruck, Innsbruck, Austria.
3
Department of Neuropsychiatry and Clinical Ethics, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
4
Department of Neuropsychiatry, Graduate School of Medicine, Hirosaki University, Hirosaki, Japan.
5
Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, ON, Canada.

Abstract

OBJECTIVE:

To examine characteristics of placebo responders and seek optimal criteria of early improvement with placebo for predicting subsequent placebo response in patients with schizophrenia.

METHOD:

Data of 672 patients with schizophrenia randomized to placebo in nine double-blind antipsychotic trials were analyzed. Multiple logistic regression analyses were conducted to examine associations between placebo response at week 6 (i.e., a ≥ 25% reduction in the Positive and Negative Syndrome Scale [PANSS] score) and gender, age, study locations, baseline PANSS total or Marder 5-Factor scores, and per cent PANSS score reduction at week 1. Predictive power of improvement at week 1 for subsequent response was investigated; sensitivity and specificity of incremental 5% cutoff points between 5% and 25% reduction in the PANSS total score at week 1 were calculated.

RESULTS:

Per cent PANSS total score reduction at week 1 and lower PANSS Marder disorganized thought scores at baseline were significantly associated with subsequent placebo response. A 10% reduction in a per-protocol analysis or a 15% reduction in last-observation-carried-forward analysis in the PANSS total score at week 1 showed the highest predictive power.

CONCLUSION:

These findings are informative to identify potential placebo responders at the earliest opportunity for optimal trial design for schizophrenia.

KEYWORDS:

antipsychotic agents; placebo effect; placebos; schizophrenia

PMID:
30198163
DOI:
10.1111/acps.12960

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