Predictors of first-year nonadherence and discontinuation of statins among older adults: a retrospective cohort study

Aims The aim of this study was to examine the level of and predictors of statin nonadherence and discontinuation among older adults. Methods Among 22 340 Australians aged >= 65 years who initiated statin therapy from January 2014 to December 2015, we estimated the first-year nonadherence (proportion of days covered [PDC] <0.80) and discontinuation (>= 90 days without statin coverage) rates. Predictors of nonadherence and discontinuation were examined via multivariable logistic regression. Analyses were performed separately for general beneficiaries (with a higher co-payment; n = 4841) and concessional beneficiaries (with a lower co-payment; n = 17 499). Results During the one-year follow-up, 55.1% were nonadherent (concessional 52.6%; general beneficiaries 64.2%) and 44.7% discontinued statins (concessional 43.1%; general beneficiaries 50.4%). Among concessional beneficiaries, those aged 75-84 years and >= 85 years were more likely to discontinue than people aged 65-74 years (odds ratio 1.11, 95% confidence interval 1.04-1.19 and 1.38, 1.23-1.54, respectively). Diabetes was associated with an increased likelihood of nonadherence and discontinuation, while hypertension, angina and congestive heart failure were associated with a lower likelihood of nonadherence and discontinuation. Anxiety was associated with an increased likelihood of discontinuation, but polypharmacy (concurrent use of five or more drugs) was associated with a lower likelihood of nonadherence and discontinuation. Statin initiation by a general medical practitioner was associated with both increased likelihood of nonadherence and discontinuation. Similar predictors of nonadherence and discontinuation were identified for the general beneficiaries. Conclusions Among older adults prescribed statins, first-year nonadherence and discontinuation are high. Specific population subgroups such as people aged >= 85 years, those with diabetes or anxiety may require additional attention to improve statin adherence.