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Pharmacoeconomic assessment of olanzapine in the treatment of refractory schizophrenia based on a pilot clinical study |
Sacristan J A, Gomez J C, Martin J, Garcia-Bernardo E, Peralta V, Alvarez E, Gurpegui M |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology The use of the antipsychotic drug olanzapine as a treatmentof refractory schizophrenia.
Economic study type Cost-effectiveness analysis.
Study population 25 patients with treatment refractory schizophrenia and with psychotic symptoms with a score of 24points on the Brief Psychiatric Rating Scale, at least moderately ill on the Clinical Global Impression Severity, with prominent positive symptoms, and not resistant to clozapine.
Setting Hospital. The economic analysis was conducted in Madrid, Spain.
Dates to which data relate The dates for the collection of effectiveness and resource data were not stated. 1995 prices were used.
Source of effectiveness data Effectiveness data were collected from a single study.
Link between effectiveness and cost data Costing was undertaken, in two stages, on the same patient sample as that used in the effectiveness analysis. Costs and resources for the six month period prior to the beginning of the pilot study were collected retrospectively whilst costs and resources used during the study were collected prospectively.
Study sample 25 patients were included in the study. Power calculations were not used to determine sample size. The mean age of patients was 32.32 years (SD 9.32) and 18 (72%) were male. 18 (72%)patients had been diagnosed with paranoid schizophrenia, 4 (16%) with disorganised schizophrenia, with the remaining three being undifferentiated. The number of patients excluded from the study was not stated.
Study design This was a multi-centre before-and-after study. The length of follow up was to the end of the six month treatment period. There was a loss to follow up of 12 patients (48%): 1 discontinued because of a depressive event, 2 discontinued because of a lack of compliance and the remainder because of a lack of efficacy.
Analysis of effectiveness The analysis of the clinical study was based on intention to treat. The primary health outcome used in the analysis was changes in psychopathological ratings as measured by the Spanish version of the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impression (CGI) Severity Scale and the Patient Global Impression of Improvement.
Effectiveness results Patients had significant improvements on all the clinical rating scales after both 6 weeks and 6 months of treatment. The Brief Psychiatric Rating Scale rating decreased by a mean of 15.24 (SD 21.81), total PANSS scores decreased by a mean of 25.56 (SD 36.70), and similarly PANSS positive decreased by 5.52 (SD 9.47), PANSS negative by 7.28 (SD 10.25), PANSS general by 12.76 (SD 19.45) and CGI severity by 1.44 (SD 1.53).
Clinical conclusions The authors concluded that olanzapine may be effective in the treatment of some patients with schizophrenia who did not respond to conventional antipsychotic treatment in addition to treating patients with schizophrenia which responds to conventional treatment.
Measure of benefits used in the economic analysis The authors produced no single measure of benefit within the economic evaluation.
Direct costs Direct total medical costs in the two 6 month periods were identified. Specifically these costs included hospital visits, olanzapine costs, other medication costs, partial/complete hospitalisation and diagnostic procedures. Hospital costs were derived from a recent Spanish study on the costs of schizophrenia. The costs of olanzapine were based on actual doses received. Costs specific to the study protocol were not included and instead were estimated based on a minimal standard care (three medical visits and two laboratory tests.) These direct costs were estimated from the perspective of the hospital and 1995 prices were used. Resource quantities were not reported separately.
Indirect Costs The amount of informal caring time of relatives was also estimated based on interviews with patients and caregivers. No methods were stated either for the accurate measurement of caregiver time or the methods by which this time would be valued.
Sensitivity analysis No sensitivity analysis was performed.
Estimated benefits used in the economic analysis Cost results The mean direct costs per patient in the two periods, before and during treatment respectively were Pta884,098 (+/- 889,482) and Pta850,974 (+/- 760,580). This difference was not statistically significant. When these mean costs per patient were adjusted to take account of the 3 patients for whom resource utilisation data were not available, the respective costs for the two periods were Pta945,767 and Pta906,845. These differences were again not significant. More caregiver days were required in the period before treatment than during treatment, 98 (+/- 84) and 63 (+/- 78) days respectively, although this was not statistically significant.
Synthesis of costs and benefits Authors' conclusions The authors concluded, from the pilot study, that olanzapine may be an effective treatment for some patients with refractory schizophrenia and that the use of this treatment may not lead to an increase in treatment costs compared with those prior to treatment with olanzapine. Cost effectiveness analyses to compare olanzapine with other antipsychotics need to be conducted to find support for these results.
CRD COMMENTARY - Selection of comparators No comparator treatment was used by the authors in the pilot study, although other antipsychotic drugs for the treatment of refractory schizophrenia are available.
Validity of estimate of measure of benefit The estimate of benefit was based on a small patient sample size. The results of the effectiveness analysis are therefore open to doubt and, as the authors note, patient improvement may have been due to other factors or to increased care and attention in this study.
Validity of estimate of costs Adequate information was provided on the source and nature of the direct care costs. Although the study collected information on informal caregiver inputs no costs for this time have been reported in the paper and the methods used to identify time have not been described in sufficient detail, although the authors admit that there was difficulty in obtaining this information. In addition other costs to society, such as those of the patients, have not been included.
Other issues The clinical and cost data in this study may not be generalisable to other countries. The conclusions made by the authors were suggestive of, and rightly recognised the need for, comparative economic evaluations comparing different antipsychotic treatments for which clinical studies are currently being conducted.
Implications of the study There is a need for well designed clinical and economic evaluations to compare the costs and benefits of different antipsychotic treatments for refractory schizophrenia.
Source of funding Funded by Eli Lilly and Company.
Bibliographic details Sacristan J A, Gomez J C, Martin J, Garcia-Bernardo E, Peralta V, Alvarez E, Gurpegui M. Pharmacoeconomic assessment of olanzapine in the treatment of refractory schizophrenia based on a pilot clinical study. Clinical Drug Investigation 1998; 15(1): 29-35 Indexing Status Subject indexing assigned by CRD MeSH Antipsychotic Agents; Cost-Benefit Analysis; Humans; Schizophrenia AccessionNumber 21998000356 Date bibliographic record published 28/02/1999 Date abstract record published 28/02/1999 |
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