This was a non-interventional retrospective cohort study of de novo heart failure with reduced ejection fraction (HFrEF) patients (aged ≥18 years) commencing first-line treatment on either sacubitril/valsartan or commencing or continuing angiotensin-converting enzyme inhibitors (ACEi)/angiotensin receptor blocker (ARB) therapy for HF in the United States (US) using the secondary source of data, Optum Electronic Health Records (EHR).

Inclusion Criteria:

Sacubitril/valsartan cohort:

• Prescribed sacubitril/valsartan within the identification period.
• With at least one International Classification of Diseases, 9th Revision (ICD)-9 or 10th Revision (ICD-10) code for diagnosis of HF within 30 days prior to the index date (including index date), that had non-missing sex and year of birth data.
• Active in the database for 759 days prior to index.
• With left ventricular ejection fraction (LVEF) ≤ 40% known prior to index day (including index date).
• That were treated as part of the integrated delivery network (IDN).

ACEi/ARB cohort:

• Prescribed ACEi or ARB within the identification period.
• With at least one ICD-9 or ICD-10 code for diagnosis of HF within 30 days prior to the index date (including index date), that have non-missing sex and year of birth data.
• Active in the database for 759 days prior to index.
• With LVEF ≤ 40% known prior to index day (including index date).
• That were treated as part of the IDN.

Exclusion Criteria

Sacubitril/valsartan cohort:

• That were < 18 years old at index date.
• That were prescribed sacubitril/valsartan within the baseline period or identification period (whichever was earlier) at any time prior to the index date (excluding).
• With one or more ICD-9 or ICD-10 codes for diagnosis of HF within the baseline period, excluding the 30 days prior to index in which HF was initially identified (patient should have had no prior history of HF).
• That were prescribed ACEi/ARB > 2 days before index date, and within 30 days after a HF diagnosis during the identification period (i.e. any patient included in the ACEi/ARB cohort with an earlier index date, regardless of whether LVEF was ≤ 40% or > 40%)
• With LVEF ≤ 10% as the closest value to index date (including).

ACEi/ARB cohort:

• That were < 18 years old at index date.
• That were prescribed sacubitril/valsartan within the baseline period or identification period (whichever was earlier) at any time prior to the index date, on the index date, or until ≤ 2 days after the index date.
• With one or more ICD-9 or ICD-10 codes for diagnosis of HF within the baseline period, excluding the 30 days prior to index in which HF was initially identified (patient should have had no prior history of HF).
• With LVEF ≤ 10% as the closest value to index date (including).

This was a retrospective, noninterventional cohort study