The Importance of the CALLY Index as a Non-Invasive Prognostic Biomarker in SARS-CoV-2 Infected Patients: An Analytical Study

Objective: To test the ability of the C-reactive protein-albumin-lymphocyte (CALLY) index to predict in-hospital mortality in hospitalized SARS-CoV-2-infected patients. Material and Methods: The present study was a retrospective, single-center study. The study population consisted of inpatients who tested positive for the reverse transcription-polymerase chain reaction test for SARS-CoV-2 between January 1, 2023, and April 15, 2023. The demographic data of the patients, vital parameters, the presence of respiratory symptoms, comorbidities, laboratory findings, and in-hospital mortality were recorded. The ability of the CALLY index to predict in-hospital mortality was tested with a receiver operating characteristic analysis and odds ratios. Results: The study population consisted of 170 inpatients. The CALLY index was significantly lower in survivors [6.5 (2.8-14.0) vs 2.0 (1.1-5.7) p< 0.001] (Mann-Whitney U test). The area under the curve for the CALLY index, C-reactive protein, albumin, and lymphocyte count were 0.700, 0.670, 0.660, and 0.630, respectively. At a cut-off value of 2.724, the CALLY index had a sensitivity of 76.15% and a specificity of 62.50%. A CALLY index below 2.724 increased the risk of in-hospital mortality by 5.32 times. The risk of in-hospital mortality was increased 4.02 times by a CRP above 152.13 mg/dL, 4.07 times by an albumin value below 33.55 g/dL, 3.84 times by a lymphocyte count below 0.58 103/µL, and 5.32 times by a CALLY index below 2.724. Conclusion: The CALLY index is a predictor of in-hospital mortality among hospitalized SARS-CoV-2-infected patients. This index also showed a superior predictive ability for in-hospital mortality than C-reactive protein, albumin, or lymphocyte count alone.