On-Admission Anemia and Survival Rate in COVID-19 Patients

Background: Anemia often worsens the severity of respiratory illnesses, and few studies have so far elucidated the impact of anemia on COVID-19 infection. This study aimed to evaluate the effect of anemia at admission on the overall survival of COVID-19 patients using AFT models.Methods: This registry-based, single-center retrospective cohort study was conducted in a university hospital in Ilam, the southwest of Iran, between March 2020 and September 2021. AFT models were applied to set the data of 2,441 COVID-19 patients. Performance of AFT models was assessed using AIC and Cox-Snell residual. On-admission anemia was defined as Hb concentration <120 g/l in men, <110 g/l in women, and <100 g/l in pregnant women.Results: The median in-hospital survival times for anemic and non-anemic patients were 27 and 31 days, respectively. Based on the AIC and Cox-Snell residual graph, the Weibull model had the lowest AIC and it was the best fitted model to the data set among AFT models. In the adjusted model, the results of the Weibull model suggested that the anemia (adjusted TR: 1.04; 95% CI: 1.00-1.08; p = 0.03) was the accelerated factor for progression to death in COVID-19 patients. Each unit of increase in hemoglobin in COVID-19 patients enhanced the survival rate by 4%.Conclusion: Anemia is an independent risk factor associated with the risk of mortality from COVID-19 infection. Therefore, healthcare professionals should be more sensitive to the Hb level of COVID-19 patients upon admission.

Anemia and risk of Mortality in COVID-19 infection: Application of accelerated failure time models

Background: Anemia typically worsens the severity of respiratory illnesses, while few studies have so far elucidated the impact of anemia on COVID-19 infection. The aim of this study was to evaluate the effect of anemia at admission on overall survival in patients with COVID-19 infection using accelerated failure time models (AFT). Methods: This is a registry-based, single-center retrospective cohort study of in-patients COVID-19 infection between March 5, 2020, and September 10, 2021, in the university hospital in Ilam, southwest of Iran. In this study, AFT models are applied to the data set of 2441 COVID-19 patients. Performance among AFT models was assessed using Akaike’s Information Criterion (AIC) and visual Cox-Snell residual. Hemoglobin (Hb) concentrations at admission <120 gr/l in men, <110 gr/l in women and <100gr/l in pregnant women were considered anemia. Results: The in-hospital median survival time for anemic and non-anemic patients was 27 and 31 days, respectively. AIC and Cox-Snell residual graph showed that the Weibull model had the lowest AIC and was the best-fitted model to the data set among AFT models. In the adjusted model, the results of the Weibull model showed that the anemia (adjusted Time Ratio;1.04, 95% CI: 1.00 - 1.08, P = 0.03), was the accelerated factor for progression to death in COVID-19 infection. Each additional unit Hb level was shown to increase the 4% survival rate in COVID-19 patients. Conclusion: anemia is an independent risk factor associated with mortality COVID-19 infection, and healthcare professionals should be more sensitive to the Hb levels of COVID-19 patients upon admission. Of great importance was awareness of anemia as a risk factor for mortality in COVID-19 patients.