Decade-long temporal trends in the utilization of preventive medicines by centenarians

What is known and objective: Centenarians represent a population of individuals with delayed disability and are an ideal representation of ageing well; however, studies related to medicine use in this population are scarce. Our study aimed to explore the temporal trends associated with the utilization of preventive medicines in centenarians. Methods: A repeated cross-sectional analysis was conducted from 1st January 2006 to 31st December 2015 for all individuals ≥100 years old on the date of dispensing, captured in New Zealand's pharmaceutical claims data set. The variable medication possession ratio (VMPR) was used to identify medicines use as preventive, and was calculated by aggregating days’ supply from the first to the last prescription divided by time between the last prescription date plus days’ supply and the first prescription date. Poisson regression was used to examine the dispensing trends for low-dose aspirin, clopidogrel, warfarin, dabigatran, statins and bisphosphonates with a VMPR ≥0·8. Results: Dispensing of aspirin [incident rate ratio (IRR) 0·92, 95% CI: 0·90–0·94], clopidogrel (IRR 0·91, 95% CI: 0·90–0·93) and aspirin with clopidogrel (IRR 0·81, 95% CI: 0·79–0·82) declined significantly over the study period. Similar trends were observed for statins (IRR 0·98, 95% CI: 0·96–1·00) and bisphosphonates (IRR 0·73, 95% CI: 0·71–0·75). Utilization of both the anticoagulants studied increased significantly: warfarin (IRR 1·04, 95% CI: 1·02–1·06) and dabigatran (IRR 1·11, 95% CI: 1·06–1·16). What is new and conclusion: Over a decade, dispensing of preventive medicines for centenarians decreased marginally for antiplatelets and statins. A substantial decrease in bisphosphonates use and an increase in anticoagulant use were noted for the same period. Temporal trends provide an opportunity to investigate uptake of guideline-based prescribing in this age group.