Posted by Phillipa on February 22, 2010, at 21:45:10
Evidently there was a mistaken believe that atypical antipsychotics were safer for TD in earlier studies Not so. Read study. Phillipa
From Reuters Health Information
Tardive Dyskinesia Rates Remain High With Atypical Antipsychotics
NEW YORK (Reuters Health) Feb 19 - Although atypical antipsychotics have a better safety reputation than conventional antipsychotics, they actually pose similar risks for tardive dyskinesia, according to the first prospective study to evaluate the issue.
In an online report February 9 in the Journal of Clinical Psychiatry, the researchers note that, comforted by studies backing the relative safety of the next generation drug class, clinicians have adopted atypical antipsychotics such as aripiprazole, olanzapine and quetiapine for disorders well beyond schizophrenia, the classic and still most frequently cited indication for the drugs.
Lead author Dr. Scott Woods of Yale University's Department of Psychiatry told Reuters Health that studies documenting low tardive dyskinesia risk in atypical antipsychotics were poorly designed. One by one, the perceived advantages of the atypical drugs, such as fewer cognitive side effects, better efficacy and lower risk for movement disorders have "dwindled away," Dr. Wood said, and there's little remaining justification for the high prices.
"The tardive dyskinesia advantage was the strongest remaining advantage for this class of drug against its competitors," Dr. Woods observed. "It was due to the unfortunate design of the studies that were relied upon for detecting the advantages in the first place."
Dr. Woods and his coauthors, all at Yale in New Haven, Connecticut, focused their study on the diagnosis of tardive dyskinesia. They note in their report that extrapyramidal signs such as akathisia and parkinsonian tremors are common in the first three months of antipsychotic treatment. These disorders are usually treatable, but they can be mistaken for more serious tardive dyskinesias. In general, most atypical antipsychotics do cause fewer extrapyramidal signs in the early period, leaving the impression of less tardive dyskinesia when strict diagnostic criteria are not applied, the Yale researchers believe.
The study enrolled outpatients at the Connecticut Mental Health Center, which sees a large population of uninsured, unemployed and chronic patients. Any patient who had been on antipsychotic medications for at least 3 months was eligible, as long as another neurologic disease did not interfere with the prospective diagnosis of tardive dyskinesia.
If patients had tardive dyskinesia at initial examination or had been previously diagnosed with the disorder, they were not included in the analysis, leaving 352 at risk subjects who were examined with the Abnormal Involuntary Movement Scale (AIMS) twice each visit, with six month follow-ups.
Observers who had been specially trained to evaluate the patients detected 52 new tardive dyskinesia cases, which tabulates to a risk of 19.7% over 3.9 years.
Most of the patients were not na�ve to conventional antipsychotic drugs. When the correlations between the patients were factored with a model adjusting for age, race, years of conventional antipsychotic exposure and a calculated chlorpromazine-equivalent dose, use of atypical drugs only was associated with a one-third lower relative risk compared to use of conventional drugs alone (RR = 0.68). Patients taking both classes had a doubled relative risk for tardive dyskinesia (RR = 1.85).
Patients prescribed atypical antipsychotics for affective disorders had a significantly lower relative risk for tardive dyskinesia than schizophrenia patients (RR = 0.15 vs RR = 0.97).
Previous studies tracked patients for about one-third as long as this new study, which followed some subjects for up to 4 years. The earlier studies reported significantly lower tardive dyskinesia risks overall. Compared to a Yale study in the 1980s, there was no significant difference in tardive dyskinesia rates between schizophrenic patients taking atypicals today versus those on conventional antipsychotics in the earlier cohort.
Dr. Woods concedes it may be most appropriate to consider the study as characterization of tardive dyskinesia rates in the current era rather than as a head-to-head comparison of risk profiles with conventional and atypical drugs. Still, in the small percentage of atypical users who were na�ve to conventional drugs, the rates were statistically similar.
"It's definitely sad news for the patients," Dr. Woods said. "I wish that the newer drugs did have this advantage," adding that it's important for prescribing doctors to know what the risks of the drugs are, so they and their patients can make informed choices.
J Clin Psychiatry 2010.
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thread:937717
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