Introduction: The necessary evidence of new therapies of clinical interest extends beyond clinical trials in a less controlled population and closer to clinical practice justified since several years the need of conducting observational, noninterventional studies. Observational studies must include epidemiological (quantitative observational) data to define prevalence and natural history of the target conditions. Moreover, pharmacological interventions in "naturalistic" patients populations, selected by clinicians as per clinical judgment within the scope of the target disease will allow to generate data to complement clinical trials. Clinical trials designed to show robust data on efficacy and tolerability particularly during registration trials must be complemented by robust observational research to confirm and better describe clinical effectiveness in the target population. A noninterventional, observational trial is a study where the medicinal product(s) is (are) prescribed in the usual manner in accordance with the terms of the marketing authorization. The assignment of the patient to a particular therapeutic strategy is not decided in advance by a trial protocol but falls within current practice and the prescription of the medicine is clearly separated from the decision to include the patient in the study. No additional diagnosis or monitoring procedures shall be applied to the patients and epidemiological methods shall be used for the analysis of collected data. Olanzapine is a new antipsychotic therapy registered in Europe for the treatment of schizophrenia since 1996.
Aims of the study: The primary objective of this observational research was to study the evolution of the olanzapine dosage under naturalistic settings. Secondary objectives included patients characteristics, severity of disease, therapeutic evolution and coprescriptions, in a patient's cohort, suffering from schizophrenia, adult patients, diagnosis based on ICD-10; patients were followed during a total of 12 months.
Design of the study: The cohort study was conducted in France. Between the period of June 2000 and February 2001, 407 psychiatrics randomized to participate in the study had consolidated the patient's cohort.
Results: A total of 1810 patients were included, 1093 (60, 4%) male, 717 (39, 6%) females. Age was recorded for a total of 1802 (99, 6%) patients, mean age was 37.8 years as per inclusion criteria and patients consent according to current regulations. Patients entered in the cohort as per clinicians decision underwent a treatment with olanzapine during an outpatient's consultation or at hospitalization. More than two thirds of the patients were followed up during 12 months after onset of this treatment. Clinical outcome was assessed at three, six, nine and 12 months following cohort inclusion using the following tools: CGI, PANSS, Calgary and GAF; as per CGI 78% of the patients cohort were severely ill, the mean PANSS score was 94.1. At second month of treatment clinicians were requested to very well document any changes in olanzapine dosage as well as reasons for the dosage modifications and potential coprescriptions.
Discussion: The daily mean dosage of olanzapine was 9.5mg at initiation of treatment, 10.5mg after one month and 11.2mg after 12 months of follow-up. The increase of the dosage after one month was associated with factors such as younger age, schizophrenia diagnosis and severity of the symptoms as measured by CGI and PANSS scores evolution, low initial dosage and hospitalization at treatment initiation. Within the 1810 participants included in the cohort, 1383 (76.5%) received a coprescrition of a psychotropic, for example, 811 (44.8%) a benzodiazepine, 506 (28.0%) an antidepressant. Among the patients cohort that were followed during 12 months, all the clinical and patient-functioning indicators progressed in the direction of a significant improvement.