Loop diuretics, heart failure diagnosis and outcome in primary care

Background
Loop diuretics are commonly prescribed in primary care. We explored HF assessment, diagnosis, and outcomes following a loop diuretic prescription.

Methods & results
The Clinical Practice Research Datalink Gold database linked to Hospital Episode Statistics (HES) and Office for National Statistics mortality registry in the UK was used to identify patients prescribed loop diuretics, and subsequent HF diagnoses. HF assessment was defined as natriuretic peptide (NP) testing, echocardiography, or out-patient cardiology referral. NP thresholds recommended by National Institute of Health and Care Excellence (NICE) and European Society of Cardiology (ESC) were explored. The primary endpoint was HF events (presentation to primary care with symptoms of HF, HF hospitalisation, or all-cause mortality). A total of 71,847 patients were prescribed a loop diuretic without a diagnosis of HF; 9876 (14 %) underwent HF assessment and 1483 (15 %) were diagnosed with HF within five years. Of those who were assessed, 5316 (54 %) had NP testing: 1937 (36 %) and 3200 (60 %) patients had NP concentrations above the NICE and ESC referral thresholds, respectively. Of those above the NICE threshold, 701 (36 %) were referred to cardiology. Compared to those who were not referred, there was a lower rate of all-cause mortality (47 % vs. 57 %; P < 0.001; hazard ratio = 0.87 (95 % confidence interval 0.76–0.99); P = 0.04).

Conclusions
One in seven patients without HF prescribed a loop diuretic undergo HF assessment, one in six of those assessed had a HF diagnosis. Specialist referral in patients with raised NP was associated with a lower risk of death.