Serum Albumin, Globulin and Albumin–Globulin Ratios as Biomarkers of Clinical Outcomes in COVID-19 Pneumonia

Objective: Low serum albumin has been linked to morbidity and mortality in critically ill patients, including those with COVID-19. Whether serum globulin levels and albumin/globulin ratios (AGRs) can serve as biomarkers in COVID-19 is less well-characterized. This study assessed serum total protein, albumin, globulin levels, and AGR in relation to clinical outcomes in adults hospitalized with COVID-19 pneumonia. Methods: A retrospective EMR analysis was conducted among 569 hospitalized patients with COVID-19 pneumonia identified during the study period, of whom 60 met inclusion criteria of the required clinical immunologic and laboratory data and comprised the final analytic cohort. Variables included demographics and laboratory markers (total protein, albumin, globulin, immunoglobulins, CRP, and IL-6). The study evaluated: (1) Charlson Comorbidity Index (CCI), (2) Charlson 10-Year Estimated Survival (C10YES), (3) clinical severity using the NEWS-2 score, (4) length of hospital stay (LOS), and (5) mortality. Spearman correlations, chi-square tests, and regression analyses were conducted. Results: Albumin was independently associated with CCI, C10YES, and LOS in adjusted models (p = 0.01, p = 0.004, and p < 0.001, respectively), as was AGR (p = 0.012, p = 0.006, and p = 0.024, respectively). Decreasing total protein levels were independently associated with higher NEWS-2 scores, lower C10YES, and longer LOS (p = 0.009, p = 0.042, and p < 0.001, respectively). Increasing age was associated with longer LOS after adjustment for sex and the other plasma proteins. Globulin levels were not associated with clinical outcomes. Conclusions: Lower serum total protein was associated with higher COVID-19 severity, and lower albumin and AGR were associated with greater morbidity, lower predicted survival, and longer LOS. Increasing age was associated with longer LOS. In patients hospitalized with COVID-19 pneumonia, albumin and AGR may serve as potential biomarkers facilitating personalized risk stratification of hospital course and recovery.