Comparison of Serum Electrolyte Levels at Admission in COVID-19 Patients Based on Outcomes: A Retrospective Study During the Delta Variant Outbreak

Background: The accurate evaluation of patient prognosis, prediction of mortality rates, and anticipation of long-term illness sequelae continue to pose significant challenges for clinicians managing COVID-19. Objectives: This study sought to ascertain the association between serum electrolyte levels at hospitalization and mortality in patients infected with the Delta variant of COVID-19. Methods: This retrospective study included 316 hospitalized COVID-19 patients. Demographic data, clinical characteristics, and admission serum electrolyte and albumin levels were collected. Receiver Operating Characteristic (ROC) curve analysis was performed to assess the predictive value of individual biomarkers. Multivariate logistic regression was then used to identify independent predictors of mortality, adjusting for potential confounders including age. Results: The mean age of the study population was 59.53 ± 15.92 years, with deceased patients significantly older (68.86 ± 15.92 years) than discharged patients (56.80 ± 16.82 years). Initial comparisons showed significant differences in sodium (Na), potassium (K), and albumin levels between the two groups. The ROC curve analysis indicated moderate predictive power for Na [area under the curve (AUC) = 0.637] and K (AUC = 0.605), while calcium (Ca), magnesium (Mg), and albumin showed poor or no predictive value. However, multivariate logistic regression revealed that only advanced age (OR = 1.033, 95% CI: 1.001 - 1.066, P = 0.040) and longer hospital stay (OR = 1.130, 95% CI: 1.022 - 1.250, P = 0.017) were independently associated with increased mortality. Serum electrolyte and albumin levels did not remain significant predictors after adjustment for these factors. Conclusions: This study confirms advanced age and longer hospital stay as independent risk factors for mortality in COVID-19 patients. While initial analyses suggested an association between elevated serum Na and K levels at admission and higher mortality, these correlations did not remain statistically significant after adjusting for age and length of hospital stay in multivariate analysis. Further research in larger, diverse populations is recommended to explore these relationships.