Background: In Danish administrative registers, ejection fraction (EF) is not recorded, which is a considerable limitation for correct subclassification of patients with heart failure (HF). We hypothesized that a diagnosis of HF combined with the recorded prescription of both renin-angiotensin system (RAS) inhibitors and beta- blockers (RASi+BB) within 120 days could identify patients with HF and reduced ejection fraction (EF ≤40%) (HFrEF).

Methods: On two sites, we identified all patients with a first-time registration of HF as primary hospital discharge diagnosis (ICD-10: I50) between June 1, 2016, and May 31, 2018 in inpatient or outpatient settings. Patients were included if they survived the initial 120 days after discharge. Reviewing patient records, we identified patients with HFrEF, based on EF ≤ 40% and reported HF symptoms. We registered the use of RASi+BB at 120 days and calculated sensitivity, specificity and predictive values.

Results: A total of 704 consecutive patients with a primary diagnosis of HF were included, of whom 541 (77%) fulfilled the HFrEF criteria. Patients with HFrEF confirmed from patient records were younger (median age 73 compared to 79 years) and less frequently women (31% compared to 56%) compared to non-HFrEF patients. At baseline, 24 (4%) of HFrEF patients were treated with RASi+BB compared to 22 (14%) of non-HFrEF patients. At 120 days, 460 (85%) of HFrEF patients received RASi+BB as compared to 25 (15%) of non-HFrEF patients. This resulted in a positive predictive value of 95%, sensitivity of 85% and specificity of 85%.

Conclusion: In Denmark, the ICD-10 HF diagnosis combined with recorded RASi+BB treatment by 120 days after discharge has high positive predictive value and can accurately be used to identify patients with HFrEF.