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

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 million to £373.9 million (£2006) 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.

Key words: :

• Health economics
• Paliperidone XR
• Quetiapine XR
• Schizophrenia

Transparency

Declaration of funding

This study and the publication of this article were supported by AstraZeneca Pharmaceuticals LP.

Declaration of financial/other relationships

J.L. and K.J. are employees of AstraZeneca and have share options in the company. M.K. has disclosed grants from AstraZeneca, Bristol Myers Squibb and Eli Lilly and consultancy fees from Eli Lilly.

All peer reviewers receive honoraria from CMRO for their review work. Peer Reviewer 1 has disclosed that he/she is a full-time employee of a private, for-profit consultancy. Peer Reviewer 2 has disclosed that he/she has no relevant financial relationships.

Acknowledgements

The authors thank Dr Kate Davenport-Slater from Complete Medical Communications who provided editing assistance, funded by AstraZeneca.

Notes

* Presented in part at the American Psychiatric Association (APA) annual meeting in Washington, DC, USA, May 3–8, 2008