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An epidemiological investigation of off‐label anticonvulsant drug use in the Georgia Medicaid population
Author(s) -
Chen Hua,
Deshpande Aparna D.,
Jiang Rong,
Martin Bradley C.
Publication year - 2005
Publication title -
pharmacoepidemiology and drug safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.023
H-Index - 96
eISSN - 1099-1557
pISSN - 1053-8569
DOI - 10.1002/pds.1051
Subject(s) - medicine , gabapentin , anticonvulsant , pharmacoepidemiology , off label use , population , medical prescription , pharmacy , medicaid , epilepsy , psychiatry , pharmacology , family medicine , health care , alternative medicine , environmental health , pathology , economics , economic growth
Purpose The primary objective was to determine the prevalence of off‐label anticonvulsant drug use in the Georgia Medicaid population and establish what percentage of this off‐label use is evidence‐based. The second objective was to investigate differences in the prevalence of off‐label use among anticonvulsants marketed before and after 1993. The third objective was to identify patient and physician characteristics associated with off‐label use. Method The study design was a retrospective study utilizing pharmacy, inpatient, outpatient and long‐term care claims linked with eligibility files for persons with Georgia Medicaid benefits in 1999 through 2000. An anticonvulsant recipient was considered an off‐label anticonvulsant user if their anticonvulsant use did not match age or medical diagnoses in the product label. An evidence‐based off‐label use was defined as off‐label anticonvulsant use supported by at least one randomized controlled clinical trial. Logistic regression analysis was used to identify patient and physician characteristics associated with off‐label use. Results 34 676 (71.3%) of 48 648 patients on one or more anticonvulsants received an off‐label prescription for an anticonvulsant. Gabapentin was the anticonvulsant most widely used off‐label (86%). After accounting for labeled and all evidence‐based uses for the six most frequently prescribed anticonvulsants, there was a moderate to large percentage of anticonvulsant use not supported by any evidence from controlled trials (range: 19.09–57.07%). The most common comorbidities among patients prescribed the top six anticonvulsants were diabetes mellitus, depression, schizophrenia and pain. Anticonvulsants launched after 1993 had a higher prevalence of off‐label use than anticonvulsants marketed before 1993. Off‐label drug use varied by age with children and adolescents being the most likely to receive an off‐label anticonvulsant. Compared with other practitioners, neurologists were more likely to prescribe anticonvulsants off‐label. Conclusions The anticonvulsant off‐label use in the Georgia Medicaid population is very high (71%). Only a modest proportion of these off‐label uses are supported by evidence from controlled trials. Copyright © 2004 John Wiley & Sons, Ltd.