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Impact of psychotic relapse definitions in assessing drug efficacy and costs: comparison of quetiapine XR, olanzapine and paliperidone ER

Research output: Contribution to journalConference paper

Martin Knapp, Julie Locklear, Krister Jarbrink

Original languageEnglish
Pages (from-to)1593 - 1603
Number of pages11
JournalCurrent Medical Research and Opinion
Volume25
Issue number7
DOIs
Publication statusPublished - Jul 2009
Event161st Annual Meeting of the American-Psychiatric-Association - Washington, DC
Duration: 3 May 20088 May 2008

King's Authors

Abstract

Objective: The objective of this study was to illustrate the implications of using standardised psychotic relapse definitions by comparing published clinical trial relapse and drop-out rates for patients with schizophrenia. Methods: Relapse definitions from three published placebo-controlled clinical trials were standardised to facilitate pair-wise retrospective comparison of relapse outcomes in patients with schizophrenia receiving extended-release quetiapine fumarate (quetiapine XR), paliperidone extended release (paliperidone ER) and olanzapine. Relapse definitions were based on changes in the Positive and Negative Syndrome Scale score, Clinical Global Impression-Severity score and predefined Brief Psychiatric Rating Scale positive items. Economic implications of relapse outcomes were also calculated. A limitation of this study is that this was not a head-to-head comparison. In addition, patient-level data were lacking for the paliperidone ER and olanzapine studies. Results: When the relapse definition from the paliperidone study was applied to the quetiapine XR clinical trial data, 14 quetiapine XR patients (15%) relapsed compared with 23 (22%) in the paliperidone ER study. According to the olanzapine relapse definition, three quetiapine XR patients (3.2%) experienced a relapse compared with nine patients (4.0%) in the olanzapine study. An illustrative calculation of potential economic impact associated with these standardised relapse rates implied incremental expenditures ranging from 74.8 pound million to 373.9 pound million (2006) pound for paliperidone ER versus quetiapine XR treatment and no material difference with olanzapine. Conclusion: The results show that the definition of relapse has a significant impact on relapse outcomes, and associated economic implications, and that relative drug efficacy can only be considered when results are based on standardised relapse criteria.

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