Inpatient versus outpatient diagnosis of heart failure across the spectrum of ejection fraction: a population cohort study

Background Early heart failure (HF) diagnosis is crucial to ensure that optimal guideline-directed medical therapy (GDMT) is administered to reduce morbidity and mortality. Limited access to echocardiography could lead to a later diagnosis for patients, for example, during an HF hospitalisation (hHF). This study aimed to compare the incidence and outcomes of inpatient versus outpatient diagnosis of HF. Methods Electronic health records were linked to echocardiography data between 2015 and 2021 from patients in Tayside, Scotland (population similar to 450 000). Incident HF diagnosis was classified into inpatient or outpatient and stratified by ejection fraction (EF). A non-HF comparator group with normal left ventricular function was also defined. The primary outcome was time to cardiovascular death or hHF within 12 months of diagnosis. Results In total, 5223 individuals were identified, 4231 with HF (1115 heart failure with reduced ejection fraction (HFrEF), 666 heart failure with mildly reduced ejection fraction, 1402 heart failure with preserved ejection fraction and 1048 HF with unknown EF) and 992 with non-HF comparators. Of the 4231 HF patients, 2169 (51.3%) were diagnosed as inpatients. The primary outcome was observed in 1193 individuals with HF (28.1%) and 32 (3.2%) non-HF comparators and was significantly more likely to occur in individuals diagnosed as inpatients than outpatients (809 vs 384 events; adjusted HR: 1.62 (1.39-1.89), p<0.001), and this was consistent regardless of EF. For HFrEF patients first diagnosed as inpatients, those discharged on >= 2 GDMT had a reduced incidence of the primary outcome compared with those discharged on <2 GDMT (303 vs 175 events; adjusted HR: 0.72 (0.55-0.94), p=0.016). Conclusions Individuals whose first presentation was a HF hospitalisation had a significantly worse outcome than those who were diagnosed in the community. Among hospitalised individuals, higher use of GDMT was associated with improved outcomes. Our results highlight the importance of improving diagnostic pathways to allow for earlier identification and treatment of HF.