Importance of diagnostic setting in determining mortality in patients with new-onset heart failure: temporal trends in Denmark from 1997 to 2017

AIM: To investigate temporal trends in inpatient vs. outpatient diagnosis of new-onset heart failure (HF) and the subsequent risk of death and hospitalization. METHODS AND RESULTS: Using nationwide registers, 192 581 patients with a first diagnosis of HF (1997–2017) were included. We computed incidences of HF, age-standardized mortality rates, and absolute risks (ARs) of death and hospitalization (accounting for competing risk of death) to understand the importance of the diagnosis setting in relation to subsequent mortality and hospitalization. The overall incidence of HF was approximately the same (170/100 000 persons) every year during 1997–2017. However, in 1997, 77% of all first diagnoses of HF were made during a hospitalization, whereas the proportion was 39% in 2017. As inpatient diagnoses decreased, outpatient diagnoses increased from 23% to 61%. Outpatients had lower mortality and hospitalization rates than inpatients throughout the study period, although the 1-year age-standardized mortality rate decreased for each inpatient (24 to 14/100-person) and outpatient (11 to 7/100-person). One-year and five-year AR of death decreased by 11.1% and 17.0%, respectively, for all HF patients, while the risk of hospitalization for HF did not decrease significantly (1.13% and 0.96%, respectively). CONCLUSION: Between 1997 and 2017, HF changed from being primarily diagnosed during hospitalization to being mostly diagnosed in the outpatient setting. Outpatients had much lower mortality rates than inpatients throughout the study period. Despite a significant decrease in mortality risk for all HF patients, neither inpatients nor outpatients experienced a reduction in the risk of an HF hospitalization.