Mineralocorticoid receptor antagonist (MRA) use in UK heart failure care: a national primary care cohort study.

Background and aims: Mineralocorticoid receptor antagonists (MRAs) reduce mortality and hospitalisation in heart failure with reduced ejection fraction (HFrEF) but are underused, despite recommendation in key guidelines. Identifying the factors contributing to underuse and addressing adherence are key components of a learning health system. We aimed to evaluate MRA prescription in people with HFrEF who would benefit, based on the UK National Institute for Health and Care Excellence (NICE) HFrEF guideline.

Methods: We used clinical code lists to identify people with HFrEF in primary care electronic health record (EHR) data from The Health Improvement Network database. For each calendar year 2014-2020, we identified individuals who met the NICE guideline criteria for MRA therapy. We fitted mixed effects logistic regression models to determine the factors contributing to MRA prescription.

Results: Among 24 135 people with HFrEF studied between 2014 and 2020, 12 150 person-years were eligible for MRA treatment. The MRA prescription rate increased from 41% to 55%. MRA prescription was inversely associated with age (OR per 1 SD, 95% CI) (0.02 (0.01, 0.03)), increasing glomerular filtration rate (0.37 (0.25, 0.55)), hypertension (0.21 (0.40, 0.78)) and prescription of antihypertensives (0.03 (0.02, 0.07)). MRA prescription was associated with male gender (6.31 (3.20, 12.4)), dilated cardiomyopathy (25.9 (7.48, 89.4)), calendar year (2.17 (1.85, 2.54) per year after study start) and prescription of sacubitril/valsartan (214 (56, 823)).

Conclusions: MRAs are underused in people with HFrEF in the UK. Although prescribing increased between 2014 and 2020, half of the cohort still did not receive the therapy. Older age, gender, comorbidities and co-prescriptions were linked to MRA underuse. Understanding the factors contributing to underprescribing at a population level should be used to inform quality improvement strategies.