Use of heart rate variability to predict hospital length of stay for COVID-19 patients: A prospective observational study

Background: As the COVID-19 pandemic continues, determining hospital demands has become a vital priority. Heart rate variability (HRV) has been linked to both the presence of viral infection and its severity. We investigate the possibility of using HRV parameters in comparison to other clinical parameters for predicting the hospital length of stay (LOS) for COVID-19 patients. Methods: This was a population-based cohort study. Measurements were performed in a specialized hospital for respiratory disease, dedicated to COVID-19. Patients were polymerase chain reaction positive for COVID-19 and on their 1st day of admission. Heart period, respiratory sinus arrhythmia (RSA), low frequency (LF) HRV, and vagal efficiency were calculated from electrocardiogram signals. This study investigated the correlation of HRV, demographic, and laboratory parameters with hospital LOS. Results: Forty-one participants were recruited, with a significant relationship, observed between hospital LOS and some demographic and clinical parameters such as lymphocyte count, age, and oxygen saturation of arterial blood. There was a negative relationship between LF and hospital LOS (r = −0.53, 95% confidence interval: −0.73, −0.24). Higher vagal efficiency predicted shorter hospital LOS in patients younger than 40 years of age (19.27% shorter hospital LOS was associated with a one SD higher value of VE, P = 0.007). Conclusion: HRV measurement is a non-invasive, inexpensive, and scalable procedure that produces several metrics, some of which are useful for predicting hospital LOS and managing treatment resources during COVID-19 pandemic.