Anemia as a risk factor for disease progression in patients admitted for COVID-19: data from a large, multicenter cohort study

Abstract

In respiratory infections, anemia is both a consequence of acute inflammation and a predictor of poor clinical outcomes. There are few studies investigating the role of anemia in COVID-19, suggesting a potential role in predicting disease severity. In this study, we aimed to assess the association between the presence of anemia at admission and incidence of severe disease and death in patients hospitalized for COVID-19. Data from all adult patients admitted for COVID-19 in University Hospital “P. Giaccone” Palermo, and University Hospital of Bari, Italy, were retrospectively collected from 1st of September 2020 to 31 August 2022. The association between anemia (defined as Hb < 13 g/dl and < 12 g/dl in males and females, respectively), in-hospital mortality and severe COVID-19 was tested using a Cox’s regression analysis. Severe COVID-19 forms were defined as admission to intensive or sub-intensive care unit or a qSOFAscore ≥ 2 or CURB65scores ≥ 3. p values were calculated using the Student’s t test for continuous variables and the Mantel–Haenszel Chi-square test for categorical ones. The association between anemia and the mortality was made using a Cox’s regression analysis, adjusted, in two models, for the potential confounders and using a propensity score. Among the 1562 patients included in the analysis, prevalence of anemia was 45.1% (95% CI 43–48%). Patients with anemia were significantly older (p < 0.0001), reported more co-morbidities, and presented higher baseline levels of procalcitonin, CRP, ferritin and IL-6. Overall, the crude incidence of mortality was about four times higher in patients with anemia compared to those without. After adjusting for 17 potential confounders, the presence of anemia significantly increased the risk of death (HR = 2.68; 95% CI: 1.59–4.52) and of risk of severe COVID-19 (OR = 2.31; 95% CI: 1.65–3.24). The propensity score analysis substantially confirmed these analyses. Our study provides evidence that, in patients hospitalized for COVID-19, anemia is both associated with a more pronounced baseline pro-inflammatory profile and higher incidence of in-hospital mortality and severe disease.

Long-Term Impairment of Working Ability in Subjects under 60 Years of Age Hospitalised for COVID-19 at 2 Years of Follow-Up: A Cross-Sectional Study

“…In line with other studies, our finding indicates that administering high-flow oxygen treatment during the acute phase of COVID-19, preventing oxygen deficiency in various tissues, may have a protective effect against post-infection sequelae [29]. This association can be related to the increased frequency of post-discharge health evaluations by suggesting that many mechanisms responsible for the post-COVID-19 state are not directly associated with acute lung injury but depend on multi-factorial processes [30].…”

Postoperative pneumonia after femoral fracture surgery: an in-depth retrospective analysis

“…Similar to our study results, in a study including 3147 patients, they found a postoperative pneumonia rate of 5.8%, and they found age to be an independent risk factor for postoperative pneumonia [ 18 ].n In a multicenter retrospective study, they found that older age was associated with a higher risk for aspiration pneumonia in patients with hip fractures [ 33 ]. Moreover, low hemoglobin levels on admission have been linked to increased severity and adverse outcomes in various infectious diseases [ 34 , 35 ]. In the context of pneumonia, reduced hemoglobin levels may reflect compromised oxygen-carrying capacity, potentially exacerbating tissue hypoxia and impairing the immune responses that combat infection [ 35 ].…”

“…Moreover, low hemoglobin levels on admission have been linked to increased severity and adverse outcomes in various infectious diseases [ 34 , 35 ]. In the context of pneumonia, reduced hemoglobin levels may reflect compromised oxygen-carrying capacity, potentially exacerbating tissue hypoxia and impairing the immune responses that combat infection [ 35 ]. Furthermore, a previous study found that low hemoglobin levels upon admission were significantly associated with 6-month mortality in hip fracture patients [ 36 ].…”

COVID-19: The Development and Validation of a New Mortality Risk Score

“…Most studies, including ours, have shown that anemia is an independent predictor of mortality and that each unit of increase in Hb in COVID-19 patients enhanced the survival rate by 4% [30,37,38]. A meta-analysis based on risk factor-adjusted effect estimates indicated that anemia was independently associated with a significantly elevated risk for mortality among COVID-19 patients [39], while another study documented that in COVID-19 patients, anemia is both associated with a more pronounced baseline pro-inflammatory profile and a higher incidence of in-hospital mortality and severe disease [40].…”