Discrepancies between Prescribed and Defined Daily Doses of Four-Pillar Therapy in Congestive Heart Failure Patients

introduction: The Defined Daily Dose (DDD) is a statistical metric for quantifying drug utilization that does not always align with the Prescribed Daily Dose (PDD). This study aimed to identify the discrepancies between prescribed daily dose (PDD) and defined daily dose (DDD) among congestive heart failure (CHF) patients. methods: A single-center, prospective observational study was conducted among patients with heart failure at the outpatient Cardiology Department over a period of three months. All eligible prescrip-tions containing guideline-directed medical therapy (GDMT) were included, irrespective of the pa-tient’s sex, and for those aged ≥18 years with New York Heart Association (NYHA) class I–III heart failure. Standard definitions of DDD and PDD were employed. A drug registry was curated on an ad hoc basis that encompassed all relevant patient and medication data, from which DDD and PDD were computed. results: A total of 84 eligible patients [63 (75%) males and 21 (25%) females] with a mean age of 60.08 ± 10.11 years were recruited to the study with consent. The majority (94%) were diagnosed with heart failure with reduced ejection fraction (HFrEF), 44% were de novo, and 48% belonged to NYHA class III. A total of 685 medicines were used among participants, with an average of 8.2 (mean 10.54). However, only 37% of medicines were from GDMT, where the most commonly prescribed drugs per patient were β-blockers (89%; n = 253), followed by 68% of SGLT2 inhibitors, 67% of ARNI, and 50% of MRA. The average PDD: DDD ratio for four-pillar therapy ranged from 0.23 (β-Blockers) to 0.33 (MRA) and 1 (SGLT2-i). Except for GDMT, the PDD was 0.06 DDD for Enoxap-arin, 1.14 DDD for Glimepiride, and 2.0 DDD for Rosuvastatin. discussion: The PDDs were lower than the DDDs for most of the prescribed drugs. These discrep-ancies do not necessarily relate to real-time patient characteristics. conclusion: The variability of PDD and DDD for most drugs suggests the need for further monitor-ing to optimize patient care.