Research Fellow School of Population Health, Faculty of Medicine and Health, University of New South Wales, Sydney, Australia, Australia
Background: The burden of cardiovascular disease is increasing worldwide, with many people treated for multiple cardiovascular conditions. Few studies have investigated adherence to multiple medicines across different cardiovascular therapeutic groups in the same population, nor the impact that multi-medicine use has on adherence and persistence to cardiovascular therapy.
Objectives: To examine patterns of adherence and persistence to medicines for cardiovascular disease treatment or prevention in Australia, including among people on multi-medicine use.
Methods: Using national dispensing claims for a 10% random sample of people, we identified four groups of adults (≥18 years) initiating antihypertensives, statins, oral anticoagulants, or antiplatelets in 2018; people could contribute to multiple groups. We defined initiation as no dispensing of medicines from the same group in the year prior. We measured persistence to first break in therapy (60-day gap). We used the proportion of days covered (PDC) to estimate adherence within 1, 2 and 3 years of initiation, and from first to last dispensing (‘while on therapy’). We reported outcomes by sex, age group and cardiovascular multi-medicine use.
Results: We identified 83,687 people initiating antihypertensives (n=37,941), statins (n=34,582), oral anticoagulants (n=15,435) or antiplatelets (n=7,726). Over one-thirds of people had multi-medicine use, reaching 92% among antiplatelet users. Around one-fifth of people discontinued therapy within 90 days, increasing to around half of people within the first year. Persistence rates dropped to 17.5% (antiplatelets) and 37.3% (anticoagulants) at three years. While many people were adherent according within the first year (between 40.5% of statin and 55.6% of antiplatelet users), these rates were higher when restricted to time while on therapy (53.2% and 80.5%, respectively). Adherence and persistence increased with age and sex differences were not consistent. People with multi-medicine use had higher persistence and adherence than people using medicines from only one cardiovascular group.
Conclusions: Persistence and adherence to cardiovascular medicines are suboptimal and decrease since time from initiation, highlighting a need for strategies to increase support among people initiating therapy. Multi-medicine use is common and people using multiple cardiovascular medicines had high rates of persistence and adherence, highlighting increased complexity of therapy may not impair compliance to treatment.
