Background The aim of this study was to investigate the association between serum albumin levels in the ED and the severity of SARS-CoV-2 infection. Methods This is a retrospective observational study conducted from 15 March 2020 to 5 April 2020 at the EDs of three different hospitals in Italy. Data from 296 patients suffering from COVID-19 consecutively evaluated at EDs at which serum albumin levels were routinely measured on patients’ arrival in the ED were analysed. Albumin levels were measured, and whether these levels were associated with the presence of severe SARS-CoV-2 infection or 30-day survival was determined. Generalised estimating equation models were used to assess the relationship between albumin and study outcomes, and restricted cubic spline (RCS) regression was used to plot the adjusted dose-effect relationship for possible clinical confounding factors. Results The mean albumin level recorded on entry was lower in patients with severe SARS-CoV-2 infection than in those whose infections were not severe (3.5 g/dL (SD 0.3) vs 4 g/dL (SD 0.5)) and in patients who had died at 30 days post-ED arrival compared with those who were alive at this time point (3.3 g/dL (SD 0.3) vs 3.8 g/dL (SD 0.4)). Albumin <3.5 g/dL was an independent risk factor for both severe infection and death at 30 days, with adjusted odd ratios of 2.924 (1.509–5.664) and 2.615 (1.131–6.051), respectively. RCS analysis indicated that there was an adjusted dose–response association between the albumin values recorded on ED and the risk of severe infection and death. Conclusion Albumin levels measured on presentation to the ED may identify patients with SARS-CoV-2 infection in whom inflammatory processes are occurring and serve as a potentially useful marker of disease severity and prognosis.

• The severity of SARS-CoV-2 patients is difficult to quickly assess in the ED. • The ABG test is a quick and easy tool that can help identify more severe patients. • CT cannot be used on all suspected SARS-CoV-2 infected patients admitted in ED. • The CT volumetry correlates well with the values of severity reported by the ABG test.

Background: Infections in emergency departments (EDs) are insidious clinical conditions characterised by high rates of hospitalisation and mortality in the short-to-medium term. The serum albumin, recently demonstrated as a prognostic biomarker in septic patients in intensive care units, could be an early marker of severity upon arrival of infected patients in the ED. Aim: To confirm the possible prognostic role of the albumin concentration recorded upon arrival of patients with infection. Methods: A prospective single-centre study was performed in the ED of the General Hospital of Merano, Italy, between 1 January 2021 and 31 December 2021. All enrolled patients with infection were tested for serum albumin concentration. The primary outcome measure was 30-day mortality. The predictive role of albumin was assessed by logistic regression and decision tree analysis adjusted for Charlson comorbidity index, national early warning score, and sequential organ failure assessment (SOFA) score. Results: 962 patients with confirmed infection were enrolled. The median SOFA score was 1 (0–3) and the mean serum albumin level was 3.7 g/dL (SD 0.6). Moreover, 8.9% (86/962) of patients died within 30 days. Albumin was an independent risk factor for 30-day mortality with an adjusted hazard ratio of 3.767 (95% CI 2.192–6.437), p < 0.001. Decision tree analysis indicated that at low SOFA scores, albumin had a good predictive ability, indicating a progressive mortality risk reduction in concentrations above 2.75 g/dL (5.2%) and 3.52 g/dL (2%). Conclusions: Serum albumin levels at ED admission are predictive of 30-day mortality in infected patients, showing better predictive abilities in patients with low-to-medium SOFA scores.