Temporal trends in the utilisation of preventive medicines by older people: A 9-year population-based study

Background: For older individuals with multimorbidity the appropriateness of prescribing preventive medicines remains a challenge. Objective: Investigate the prevalence and temporal trends in utilisation of preventive medicines in older New Zealanders from 2005 to 2013 stratified according to age, sex, ethnicity and district health board domicile. Methods: A repeated cross-sectional analysis was conducted on pharmaceutical dispensing data for all individuals' ≥65 years. Variable medication possession ratio (VMPR) was used to measure adherence. Prescribing of low-dose aspirin, clopidogrel, dipyridamole, warfarin, dabigatran, statins and bisphosphonates with a VMPR. ≥. 0.8 were examined. Results: Aspirin utilisation increased by 19.55% (95% CI: 19.39-19.70), clopidogrel by 2.93% (95% CI: 2.88-2.97) and dipyridamole decreased by 0.65% (95% CI: -0.70 to -0.59). Utilisation of aspirin with clopidogrel increased by 1.78% (95% CI: 1.74-1.81) and aspirin with dipyridamole increased by 0.54% (95% CI: 0.50-0.58%).Warfarin decreased by 0.87% (95% CI: -0.96 to -0.78) and dabigatran increased by 0.65% (95% CI: 0.60-0.70). Statins increased by 7.0% (95% CI: 6.82-7.18) and bisphosphonates decreased by 2.37% (95% CI: -2.44 to -2.30). Aspirin, clopidogrel, dabigatran and statins utilisation showed a greater increase in males. Interestingly, clopidogrel, warfarin and statins use increased in older adults aged 85+ compared to the younger age groups (65-84 years). Conclusion: To our knowledge, this is the first study investigating the prevalence and trends of preventive medicines use in older people in New Zealand. This study may facilitate further research to examine the appropriateness of prescribing these medicines in older people with multimorbidity.