Interactions cause seniors to drop antidepressants
WASHINGTON | Fri Dec 17, 2010 5:39pm EST
WASHINGTON (Reuters) - More than half of older Americans taking an antidepressant for the first time were already taking another drug that could interact with it and cause side effects, researchers reported on Friday.
And a quarter of patients who suffered side effects stopped taking antidepressants altogether, the study by a team at Thomson Reuters, the University of Southern California, Sanofi Aventis and elsewhere found.
"We found a concerning degree of potentially harmful drug combinations being prescribed to seniors," Dr. Tami Lee Mark of Thomson Reuters, parent company of Reuters, said in a statement.
Other studies have found that older adults are often taking dangerous combinations of prescription drugs, but doctors are not getting the message, the researchers report in the American Journal for Geriatric Psychiatry.
The research team used a Thomson Reuters database of claims for Medicare, the federal health insurance plan for people over 65.
They found more than 39,000 patients who started antidepressants between 2001 and 2006. "Twelve commonly reported antidepressant side effects were identified in the month after drug initiation," Mark's team writes.
More than 25 percent of the patients were prescribed antidepressants and another drug that could cause a major interaction. Another 36 percent had potential moderate interactions.
"The most common side effects were insomnia, somnolence and drowsiness, which occurred in 1,028 (2.6 percent) patients. The next most common side effect was dizziness, which was documented in 416 (1.1 percent) patients," the researchers report.
The side effects meant patients often dropped the drug they were taking. Only 45 percent of those with documented side effects refilled the prescription for the same antidepressant, and a quarter quit taking antidepressants altogether.
Many adults are at risk of this problem, the researchers point out -- other studies show that 25 percent of older adults with chronic illnesses such as arthritis or heart disease also have depression, and they have also been shown to be helped by antidepressants.
"Older adults often need to be on many medications, some of which may contribute to depression and/or interact with antidepressants. Finally, older adults metabolize medications slowly and are more sensitive to side effects than younger patients," the researchers conclude.
SOURCE: link.reuters.com/qyf72r The American Journal of Geriatric Psychiatry, online November 14, 2010.
Antidepressant Use in Geriatric Populations: The Burden of Side Effects and Interactions and Their Impact on Adherence and Costs
Mark, Tami L.; Joish, Vijay N.; Hay, Joel W.; Sheehan, David V.; Johnston, Stephen S.; Cao, Zhun
American Journal of Geriatric Psychiatry., POST AUTHOR CORRECTIONS, 13 September 2010
Mark , Tami Mark , Tami L. Ph.D., M.B.A. FN> Mark Ph.D., M.B.A. Vijay N.
Objectives: The study aimed to determine the prevalence of documented side effects and drug-drug interactions in older adults using antidepressants and their implications for adherence.
Design: Data were from the MarketScan Medicare Database, which comprises insurance claims from retirees with employer-sponsored Medicare supplemental insurance. Subjects were aged 65 years or older, new antidepressant users, and had a depression diagnosis between July 1, 2001, and December 31, 2006. Twelve commonly reported antidepressant side effects were identified in the month after drug initiation through International Classification of Diseases, Ninth Revision, Clinical Modification diagnoses. Potential drug-drug interactions involving an antidepressant and another drug were identified during the 1 year after antidepressant initiation using MicroMedex DRUG-REAX software. Multinomial logistic regression was used to determine the association of side effects and potential interactions with refills rates, switching, and discontinuation.
Results: The presence of a side effect was associated with a 4.7 percentage point increase in the probability of switching (from 16.5% to 21.7%) and a 3.7 percentage point increase in the discontinuation rate (from 22% to 25.7%). Among the 39,512 treatment-naive antidepressants users, 25.4% had potential contraindicated or major interactions, 36.1% had moderate interactions, and 38.5% had minor or no interactions. The presence of potential contraindicated or potential major interactions increased the probability of switching by 19.5 percentage points and had a minimal effect on discontinuation.
Conclusion: Although antidepressant medications have been demonstrated to be effective in treatment of geriatric depression, this study highlights the complexity of antidepressant prescribing in this population and the need for clinicians to be aware of potential drug-drug interactions and side effects.
Copyright (C) 2010 American Association for Geriatric Psychiatry
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