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Higher-than-recommended doses of antipsychotic medications may not benefit people with schizophrenia and may increase side effects

About 40 percent of people with schizophrenia insured through Medicaid in Massachusetts took daily doses of antipsychotic medications that were well above the range recommended by clinical guidelines. Higher-than- recommended dose levels were not related to better outcomes, but may have increased disturbing side effects ranging from blurred vision to muscle spasms. High dose levels had no relationship to the patient's baseline symptoms, according to a study supported in part by the Agency for Healthcare Research and Quality (HS10303). Doctors who believe that higher doses of antipsychotics are more therapeutic for schizophrenic patients need to demand studies that show the benefits of higher doses versus the risk of side effects and other clinical costs, suggest the study authors.

The researchers used Medicaid pharmacy claims data to examine the relationship between antipsychotic medication dose and patient-reported health status, medication side effects, and perception of care among 329 acutely ill adults with schizophrenia. These patients had been evaluated for hospital admission by one of eight psychiatric emergency screening teams. The researchers collected claims data on presenting symptoms and problems, referral source, and living situation at the time of the visit, as well as history of prior psychiatric treatment costs and hospitalizations.

During the study period, about 60 percent of the patients in the study received daily standardized doses within the recommended range of 300 to 1,000 chlorpromazine (CPZ) units (median dose, 611 CPZ units). Doses above the recommended guideline ranged from 1,025 to 6,067 CPZ units (median dose, 1,764 CPZ units). After adjustment for sociodemographic and clinical factors, patient health status measures were largely unrelated to guideline dose adherence. Patients rated their treatment as good regardless of dose level, yet about one-fourth of patients suffered from movement disorders, including tardive dyskinesia (involuntary movements of the mouth, trunk, or legs), and more than half had at least one medication side effect. Patients in the high-dose group had more non-movement-related side effects than others.

See "Associations between adherence to guidelines for antipsychotic dose and health status, side effects, and patient care experiences," by Barbara Dickey, Ph.D., Sharon-Lise T. Normand, Ph.D., Sue Eisen, Ph.D., and others, in the September 2006 Medical Care 44(9), pp. 827-834.

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