Time to discontinuation and self-discontinuation of olanzapine and risperidone in patients with schizophrenia in a naturalistic outpatient setting
ABSTRACT Although efficacy of antipsychotic medications is well documented, their effectiveness in real-world practice is less robust. We examined the effectiveness of olanzapine and risperidone in schizophrenia in a naturalistic setting.
We used an electronic medical records database at a Veterans Affairs Medical Center to conduct a retrospective study of all new outpatient medication trials of olanzapine (n = 221) and risperidone (n = 274) over a 2-year period beginning January 1999 in patients diagnosed with schizophrenia or schizoaffective disorder. We defined medication discontinuation as a switch between the 2 agents (most switches) or self-discontinuation when a patient is without medication supply for longer than 1 month.
Sample mean age (+/-SD) was 48.4 (+/-11.6) years; 91% were men. Discontinuation rates were high (73%), trending lower in olanzapine (70%) than risperidone (76%) (P = 0.12). Median time to discontinuation was 120 days (95% confidence interval [CI], 105-135), longer for olanzapine (150 days; 95% CI, 120-180) than risperidone (90 days; 95% CI, 71-109) (P = 0.04). Self-discontinuation was high (48%), with no significant difference between olanzapine (50%) and risperidone (46%). Switching rate was 25% and more likely to occur in risperidone (30%) than olanzapine (20%) (odds ratio, 1.72; 95% CI, 1.13-2.61).
Effectiveness of antipsychotic medications in schizophrenia may be hampered by high rates of medication self-discontinuation in outpatient practice settings. Time to discontinuation suggests that olanzapine may be more effective than risperidone. Strategies to address causes of poor adherence should be incorporated in medication algorithms to optimize their effectiveness.
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ABSTRACT: A color classification method that partitions color image data into a set of uniform color regions is described. The ability to classify spatial regions of the measured image into a small number of uniform regions can be useful for several problems, including image segmentation and image representation. The input image data are first mapped from device coordinates into all approximately uniform perceptual color space. Colors are classified by means of cluster detection in the uniform color space. The classification process is composed of two stages of basic classification and reclassification. The basic classification is based on histogram analysis to detect color clusters sequentially. The principal components of the color data are extracted for effective discrimination of clusters. At the reclassification stage, the extracted representative colors are reclassified on a color distance. Experimental results show that a fundamental set of colors composing an image with shades and shadows is extracted at the basic classification stage and that the objects in the original image are extracted at the reclassification stagePattern Recognition, 1990. Proceedings., 10th International Conference on; 07/1990
- European Neuropsychopharmacology 08/2008; 18. DOI:10.1016/S0924-977X(08)70921-0 · 5.40 Impact Factor
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ABSTRACT: This naturalistic retrospective study aims to compare effectiveness of a second-generation antipsychotic medication, risperidone, with first-generation antipsychotic medications (haloperidol and trifluoperazine) in an Asian population with first-episode schizophrenia-spectrum disorders. A total of 261 patients were assessed for time to discontinuation for any reason and specific reasons of discontinuation, controlling for baseline differences between groups. Some 90% of patients discontinued their antipsychotic medications before 18 months. Median time to discontinuation for any reason in risperidone was 69 days versus first-generation antipsychotic medications of 27 days. Specifically, the risperidone group had a longer time to discontinuation for any reason than haloperidol (HR = 0.61, p = 0.005) and trifluoperazine groups (HR = 0.63, p = 0.03), as well as a longer time to discontinuation due to intolerability of side effects than haloperidol (HR = 0.50, p = 0.008) and trifluoperazine groups (HR = 0.26, p = 0.001). There were no significant differences between medications for time to discontinuation due to lack of efficacy, patient's/family's decisions or other reasons. We conclude that there is a very high rate of discontinuation of the initial antipsychotic medications for various reasons, with risperidone having an overall longer time to discontinuation compared with first-generation antipsychotic medications.Journal of Psychopharmacology 12/2009; 24(7):973-80. DOI:10.1177/0269881109351965 · 2.81 Impact Factor