Several studies have identified a possible association between ABO blood group and COVID-19. However, studies are of variable quality and results are inconsistent. The aim of this systematic review was to synthesize the evidence on the association between ABO and the risk of COVID-19 infection and prognosis. Searches were conducted in PubMed, MedRxive and BioRxive to identify observational studies published up to May 2021. The incidence of COVID-19 and, among the COVID-19 positive patients, the risk of hospitalization, ICU admission, mechanical ventilation and mortality were also analyzed. A total of 63 studies were included, with 6,470,438 participants. Group O was associated to a significantly lower risk of COVID-19 infection (OR O vs non-O 0.88 95%CI: 0.82–0.94; I²: 91%) and group A with a higher risk (OR A vs non-A 1.08 95%CI: 1.02–1.15). No effect of ABO on the risk of hospitalization, ICU admission or ventilation was observed. Group A was associated with higher mortality (OR A vs non-A: 1.13 95%CI 1.03–1.13), group B with lower mortality (OR B vs non-B 0.88; 95%CI 0.80–0.96), and no effect with group O was observed. The quality of the evidence was rated as “very low” and “low”. Group O would present a reduced risk of COVID-19 infection, but would not influence the prognosis of the disease. Group A would be risk factor for COVID-19 infection and mortality. Group B would not modify the risk of COVID-19 infection, but would be associated to a lower mortality risk.

Worldwide, the COVID-19 pandemic has caused a decline in blood donations, between 30% and 70% in some of the most affected countries. In Spain, during the initial eight weeks after the State of Emergency was decreed on 14 March 2020, in the weekly reports of the Health Ministry, an average decrease of 20% was observed between 11 and week 25 compared with the 2018 donation. We aimed to investigate the impact of the COVID-19 pandemic on blood donations and blood distribution in four autonomous communities, and to explore the evolution of the consumption of blood components (BCs) in ten hospitals of six autonomous communities. We performed a prospective study of grouped cohorts on the donation and distribution of blood in four regional transfusion centers in four autonomous communities in Spain, and a retrospective study of the consumption of blood components in ten hospitals in six autonomous communities. Regarding donations, there was no significant decrease in donations, with differences between autonomous communities, which started between 1 and 15 March 2020 (−11%). The increase in donations in phase II (from 26 May 2020) stands out. Regarding consumption, there was a significant reduction in the consumption of packed red blood cells (RBCs) (24.5%), plasma (45.3%), and platelets (25.3%) in the central period (16 March–10 May). The reduction in the consumption of RBCs was significant in the period from 1–15 March. Conclusions: The COVID-19 pandemic has affected the donation and consumption of BCs.

Background: Preoperative anaemia is associated with poor outcomes in surgical patients, but the preoperative haemoglobin cut‐off that determines lower morbidity in total knee arthroplasty (TKA) and total hip arthroplasty (THA) is not well established.Methods: Planned secondary analysis of data collected during a multicentre cohort study of patients undergoing THA and TKA in 131 Spanish hospitals during a single 2‐month recruitment period. Anaemia was defined as haemoglobin <12 g dl⁻¹ for females and < 13 g dl⁻¹ for males. The primary outcome was the number of patients with 30‐day in‐hospital postoperative complications according to European Perioperative Clinical Outcome definitions and specific surgical TKA and THA complications. Secondary outcomes included the number of patients with 30‐day moderate‐to‐severe complications, red blood cell transfusion, mortality, and length of hospital stay. Binary logistic regression models were constructed to assess association between preoperative Hb concentrations and postoperative complications, and variables significantly associated with the outcome were included in the multivariate model. The study sample was divided into 11 groups based on preoperative Hb values in an effort to identify the threshold at which increased postoperative complications occurred.Results: A total of 6099 patients were included in the analysis (3818 THA and 2281 TKA), of whom 8.8% were anaemic. Patients with preoperative anaemia were more likely to suffer overall complications (111/539, 20.6% vs. 563/5560, 10.1%, p < .001) and moderate‐to‐severe complications (67/539, 12.4% vs. 284/5560, 5.1%, p < .001). Multivariable analysis showed preoperative haemoglobin ≥14 g dl⁻¹ was associated with fewer postoperative complications.Conclusion: Preoperative haemoglobin ≥14 g dl⁻¹ is associated with a lower risk of postoperative complications in patients undergoing primary TKA and THA.