Non-adherence to medications prescribed to patients with heart failure in general practice: prevalence, risk factors and association with mortality and hospitalisation.

Aim: In the UK, pharmacological management of patients with heart failure (HF) occurs predominantly in general practice. Using data from the Clinical Practice Research Datalink, we examined the prevalence and risk factors for medication non-adherence and its association with hospitalisation and mortality over a 9-year period.

Methods: A retrospective cohort study of 127 927 patients, ≥18 years old in England with incident HF diagnosed during 1 January 2009 to 31 December 2018. We evaluated non-adherence to any ACE inhibitor, angiotensin receptor blocker, β-blocker or mineralocorticoid receptor antagonist, over 24 months. Non-adherence was based on proportion of days covered (PDC) and defined as PDC<80%. Risk factors for non-adherence and all-cause mortality were examined using multiple logistic regression and Cox regression, respectively. Rates of any-cause emergency hospitalisations, cardiovascular disease (CVD) and HF mortality was estimated using Fine-Gray competing risk models. PDC was also assessed as a continuous variable.

Results: About 43.6% of patients were non-adherent to therapy. Crude rates of emergency admissions, all-cause, CVD and HF mortality overall were 306.8/1000, 119.6/1000, 44.6/1000 and 3.3/1000 person-years, respectively. The strongest predictor of non-adherence was any-cause hospitalisation ≤12 months prior. Non-adherence was associated with a higher rate of all-cause mortality (HR 1.31, 95% CI 1.28 to 1.33) and significantly associated with CVD-related mortality (subdistribution HR (SHR) 1.20, 95% CI 1.16 to 1.23), HF deaths (SHR 1.18, 95% CI 1.05 to 1.32) and any-cause emergency admissions (SHR 1.11, 95% CI 1.10 to 1.13). In the analysis treating PDC as a continuous variable, every 10% decrease in PDC levels was associated with a 6% increased hazard of all-cause mortality (HR 1.06, 95% CI 1.05 to 1.06) and was significantly associated with CVD, but not HF mortality.

Conclusion: Medication non-adherence over 24 months was relatively high and associated with poorer health outcomes. Interventions to improve adherence among patients with HF are needed.