Anticonvulsant drugs are among the 10 top-selling therapeutic drug classes and are frequently used for unapproved indications. The objective of this study was to examine national trends in off-label prescribing of anticonvulsant drugs in ambulatory care from 1993 to 2005, and to explore patient and physician characteristics, and other factors that might be associated with off-label prescribing of anticonvulsant drugs.
Physician office and hospital outpatient departmental visits mentioning anticonvulsant drug visits were identified from the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Medical Care Survey (NHAMCS) respectively. Anticonvulsants were classified as old anticonvulsant if approved prior to 1990 and new if approved after 1990. On-label visits were defined as visits where any type of convulsion related condition or epilepsy or other approved indications for an anticonvulsant drug was reported as the visit diagnoses or reason for office or hospital visit. Off-label visits were defined as visits at which no approved indications was reported and at least one previously reported off-label use of any of the anticonvulsants was reported. Visits unclassifiable based on these criteria were excluded from the study. Sampling weights were used to provide national estimate. OLS regression was employed in examining the association between patterns of off-label prescribing and variations in promotional activities of drug manufacturers' (free drug sampling, and physician detailing), and the publication of off-label drug use studies. Logistic regression analysis was employed in examining associations between patients, physician and visit characteristics with off-label prescribing.
During the 13 years under review, about 62% (95% CI: 59%-64%) of all anticonvulsant drug visits to both physician offices and hospitals' outpatient departments were visits at which at least one anticonvulsant drug was prescribed for an unapproved indication. There was a significant linear growth in the proportion of off-label anticonvulsant drug visits during the study period. Off-label use of new anticonvulsant drugs grew, while the off-label use of old anticonvulsant drugs remained over time, therefore the introductions of the new anticonvulsant drugs had a significant effect on the secular trend in off-label visits.
Trends in promotional activities of manufacturers and publication of off-label drug use studies were found to be associated with trends in off-label prescribing of anticonvulsant drugs, though not all association reached statistical significance. Furthermore, certain patient characteristics such age, physician characteristics such as physician specialty and visit characteristics such as number of drugs prescribed were found to be associated with off-label prescribing of anticonvulsant drugs.
Anticonvulsant drugs are increasingly used for off-label non-epileptic purposes with the magnitude of growth in off-label prescribing attributable to the new agents. In light of the present political interest in the safe and cost effective use of prescription drugs, there is an urgent need for formulation of policies that will give providers the autonomy to treat patients according to their best knowledge and judgment and at the same time ensure safe and cost effective use of prescription drugs.
|Advisor:||Winterstein, Almut G.|
|School:||University of Florida|
|School Location:||United States -- Florida|
|Source:||DAI-B 70/11, Dissertation Abstracts International|
|Subjects:||Pharmacy sciences, Public health, Epidemiology|
|Keywords:||Anticonvulsant drugs, Cost effective, Drug safety, Epilepsy, Prescription drugs|
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