Role of Hematic Iron and Anemia in SARS-CoV-2 Pathogenesis

The role of anemia and iron deficit in the pathogenesis of SARS-CoV-2 is not well established. Anemia is a common finding in patients infected with SARS-CoV-2, however few studies analyze the impact of iron metabolism changes in disease progression during SARS-CoV-2 infection. Our study analyses the influence of hemoglobin and red blood cell iron deficit at the time of infection in the prognosis of patients with COVID.

This observational retrospective study collected and analyzed data from a cohort of unvaccinated patients, collecting data on variables such as erythrocyte indices associated with iron deficiency, hemoglobin and several analytical variables associated with inflammation, and analyzing its correlation with clinical outcome. Patients were classified into three groups: non-anemic, anemic (non-iron deficiency) and iron deficiency anemic (IDA). We looked for the impact of those parameters and classification on disease progression.

We collected data of 435 patients with COVID infection, 322 patients with anemia and 113 without anemia as controls. Among patients with anemia, 159 had IDA and 163 were non-IDA patients. As expected, anemic patients had worse clinical evolution compared to non-anemic patients: ward admission 71.7% vs. 42.4%, p<0.001; ICU admission 18% vs. 7%, p=0.03. Interestingly, patients presenting with IDA at the onset of infection showed a better outcome when compared to non-iron deficiency anemic patients, with lower rate (56.6% vs. 86.5%, p<0.001) and duration (8 vs. 15 days, p<0.001) of admission to ward, ICU admission (8.1% vs. 27.6%, p<0.001) and length of ICU stay (17 vs. 23 days, p<0.001). Furthermore, patients with IDA showed less pronounced signs of an inflammatory process, as reflected by lower CRP (114 vs. 168 mg/L, p<0.001) and ferritin levels (301 vs. 1026 g/L, p<0.001). Other factors as age, sex, presence of comorbidities, ratio lymphocytes/neutrophils and maximum COHb concentration exhibited a significant influence on patient's outcome. Multivariate regression analysis showed that presence of IDA remains an independent prognostic factor that protect patients from admission to ward and/or ICU.

Our findings highlight the importance of evaluating the iron status, particularly iron deficiency anemia, in patients with COVID-19, as it is associated with a more favorable prognosis. Patients with iron deficiency anemia exhibit a more favorable outcome compared to other anemic patients. This association remains significant even after adjusting for confounding factors such as age, sex, and the presence of other comorbidities.