Anticholinesterase duration in the Australian veteran population

The aim of the present study was to determine the duration of initial anticholinesterase treatment in veteran patients in Australia. Three anti-dementia medications were investigated (donepezil, rivastigmine and galantamine) and two different setting were compared (community and residential aged care facilities).

A retrospective cohort study was performed using the Department of Veterans' Affairs pharmacy claims data. Patients were included in the cohort if they had been dispensed at least one anticholinesterase prescription (index) between 2003 and 2006, were aged 65 years or over at the time of that index dispensing, and had not been dispensed any anticholinesterase medicine in the previous 12 months. Patients were followed until discontinuation (ceased or switched), death or 1 year of follow up. Time to treatment discontinuation was analysed utilizing the Kaplan-Meier method. Cox proportional hazards models were used to compare the risk of treatment discontinuation among the three treatment groups adjusting for the effect of patients' characteristics.

Of the new users of anticholinesterases (n = 10088), 47% of those on donepezil, 46% of those on galantamine, and 47% of rivastigmine patients discontinued their initial therapy within 6 months. A total of 32% of patients who ceased therapy reinitiated it during the study period; 28% returned to the same index medication and 4% restarted therapy with a different anticholinesterase. The median treatment duration was: 199 days (95% CI, 182-208) for donepezil patients (n = 6705), 233 days (95% CI, 212-259) for galantamine patients (n = 2898), and 219 days (95% CI, 176-260) for rivastigmine patients (n = 394). Patients in community settings were more likely to discontinue their initial anticholinesterases earlier compared to those living at residential aged care facilities (relative risk, RR=1.21; 95% CI, 1.12, 1.31).

Almost half of the Australian veteran patients who initiated anticholinesterases treatment discontinued (ceased or switched) therapy within 6 months. However, one-third of those who ceased therapy reinitiated it during the study period.