[Sodium-chlorine difference as a prognostic predictor in adult patients diagnosed with COVID-19].

Background: Hyperchloremia has been associated with a greater presence of morbidity and mortality, mainly described in critically ill patients, this may be relative and absolute, which could be reflected in the sodium-chloride difference. Objective: The primary objective was to determine whether the sodium-chloride difference <31 mEq/L measured 24-48 hours after admission is a predictor of 28-day mortality in patients with COVID-19, and as secondary objectives to identify whether it is associated with higher requirement for invasive mechanical ventilation, presence of acute kidney injury and longer hospital stay. Material and methods: Retrospective, descriptive and analytical longitudinal cohort study, was done including all consecutive patients older than 16 years of any gender, admitted to the UMAE from March 1, 2020 to March 2021, which present a diagnosis of COVID-19 with RT-PCR test for SARS-CoV-2 positive. Results: A total of 722 patients were included, the difference sodium-chloride < 31 mEq/L is not associated with an increased risk of death at 28 days (p = 1.172, OR: 1.35; 95%CI, 0.87-2.08) or requirement of mechanical ventilation (p = 0.47, OR: 1.19; 95%CI, 0.76-1.86), but is associated with a higher risk of AKI (p < 0.05, OR: 2.04; 95%CI, 1.33- 3.14) and longer hospital stay (p < 0.05). Conclusions: the sodium-chloride difference < 31 mEq/L in the first hours of admission is associated with a higher risk of presenting acute kidney injury during hospital stay in patients with COVID-19, as well as a longer hospital stay.