Impact of Respiratory Infections on Hospitalized Congestive Heart Failure Patients: A Retrospective Analysis of NIS Database (2019–2022)

Background Congestive heart failure (CHF) is a leading cause of hospitalization and mortality in the elderly, with patients particularly vulnerable to adverse outcomes when exposed to infections. The evolving impact of COVID-19 on in-hospital outcomes among patients with CHF remains insufficiently understood. This study examines the temporal variations in mortality and in-hospital outcomes among CHF patients with and without COVID-19 using National Inpatient Sample (NIS) data from 2019 to 2022, with 2019 as a pre-pandemic reference year. Methods We conducted a retrospective observational study on NIS data 2019–2022. Patients aged 18–90 with CHF, identified using ICD-10-CM I50.x diagnosis codes, were included. The primary outcome was mortality, with secondary outcomes including vasopressor use, sudden cardiac arrest, acute kidney injury, pulmonary embolism, mechanical ventilation, and time to in-hospital death. The main covariate of interest is the presence or absence of a COVID-19 diagnosis. Multivariate logistic regression and Cox proportional hazards models were applied to estimate adjusted odds ratios (aORs) or hazard ratios (aHRs) controlling for demographic and comorbidities based on the Elixhauser Comorbidity Index. Results The in-hospital mortality rate of CHF patients with a COVID-19 diagnosis was significantly higher than those without COVID-19 in 2020 to 2022, although the difference narrowed in 2022. aORs (95% CI) were 6.12 (5.95–6.31), 5.71 (5.57–5.86), and 2.53 (2.46–2.60) in 2020, 2021, and 2022, respectively. By 2022, the impact of COVID-19 on mortality among CHF patients had declined to a level comparable to that of non-COVID pneumonia (aOR 2.50, 95% CI 2.45–2.56 in 2022). Among secondary outcomes, the time to in-hospital death followed a similar pattern to overall mortality, with significantly elevated risks early in the pandemic and showed a clear reduction by 2022. Other outcomes, such as mechanical ventilation and pulmonary embolism, showed an initial increase in risk followed by a decline over the same period. Conclusions Using NIS data 2019–2022, this analysis demonstrates that while COVID-19 was associated with substantially higher in-hospital mortality and adverse outcomes among CHF patients early in the pandemic, its impact progressively declined by 2022, converging to levels comparable with non-COVID respiratory infections.