Impact of psychotic relapse definitions in assessing drug efficacy and costs: comparison of quetiapine XR, olanzapine and paliperidone ER.
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 pound sterling to 373.9 million pound sterling (2006 pound sterling) for paliperidone ER versus quetiapine XR treatment and no material difference with olanzapine.


CONCLUSIONS
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.
Knapp
Martin
M
Personal Social Services Research Unit, LSE Health & Social Care, London School of Economics, UK. M.Knapp@lse.ac.uk
Locklear
Julie
J
Järbrink
Krister
K
D000328:Adult; D014150:Antipsychotic Agents / Q000191:economics* / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000191:economics / Q000627:therapeutic use; D015415:Biomarkers / Q000032:analysis; D018849:Controlled Clinical Trials as Topic; D003692:Delayed-Action Preparations / Q000627:therapeutic use; D003987:Dibenzothiazepines / Q000191:economics / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007555:Isoxazoles / Q000008:administration & dosage / Q000191:economics / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D000077152:Olanzapine; D000068882:Paliperidone Palmitate; D010919:Placebos; D011618:Psychotic Disorders / Q000175:diagnosis / Q000188:drug therapy* / Q000191:economics; D011743:Pyrimidines / Q000008:administration & dosage / Q000191:economics / Q000627:therapeutic use; D000069348:Quetiapine Fumarate; D012008:Recurrence; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
D014150:Antipsychotic Agents; D015415:Biomarkers; D003692:Delayed-Action Preparations; D003987:Dibenzothiazepines; D007555:Isoxazoles; D010919:Placebos; D011743:Pyrimidines; D001569:Benzodiazepines; D000069348:Quetiapine Fumarate; D000077152:Olanzapine; D000068882:Paliperidone Palmitate