BALTIMORE, Md -- About half of patients with Alzheimer's disease who have been prescribed oral cholinesterase inhibitors are still taking the medication after 1 year, researchers said here at the American Neurological Association (ANA) 134th Annual Meeting.
"Optimal compliance and persistence rates of oral cholinesterase inhibitors -- rivastigmine, galantamine, and donepezil -- are important factors contributing to the beneficial impact of these therapies," said Francis Vekeman, MA, BSc, Groupe d'analyse, Ltee, Montreal, Quebec, Canada, in his October 13 poster presentation.
Vekeman, a specialist in health economics and health policy, said, "Based on real-world data from a large cohort of Alzheimer's disease patients initiated on cholinesterase inhibitors, 50% were compliant during the first year following cholinesterase treatment initiation."
But persistence in taking the medication was lower, he said. After 1 year, just 36% of patients completed criteria for persistence in taking their medication. The researchers defined persistence as continuous drug use without a gap of 30 days or more between medication refills at any time after treatment initiation.
"Only 20% of the patients were persistent with their oral cholinesterase inhibitors at 2 years after initiating therapy," he said.
The researchers accessed the MedSatat MarketScan database and reviewed data on 17,717 patients who were prescribed rivastigmine, donepezil, or galantamine between January 2004 and June 2008v
During the study period, the researchers found that 15,008 patients began therapy using donepezil, 1,480 patients initiated therapy on galantamine, and 1,240 patients initiated therapy with rivastigmine. Vekeman also noted that 3,370 of the patients were being treating with antipsychotics at the time they initiated cholinesterase inhibitor therapy.
After 12 months, Vekeman determined that compliance for all patients was 49.9%. If the patients were taking memantine in addition to their cholinesterase inhibitor therapy, the compliance rate was higher, at 59.3%. But if patients were just taking 1 of the 3 oral cholinesterase inhibitors, the compliance rate was 45.9%.
Vekeman said the study, based on pharmacy claims, includes some inherent limitations, including that a filled pharmacy prescription does not guarantee that patients actually took the medication. He said that these studies also cannot assure that the billing diagnoses and pharmacy dispensing data are accurate. He added that the study did not give researchers the ability to determine the severity of illness among the patients.
The research was supported by Novartis Pharmaceuticals Corporation, East Hanover, New Jersey