Hematological and inflammatory indicators as diagnostic tools in community-acquired pneumonia, Ecuador

Abstract

Objective. To evaluate the discriminative ability of C-reactive protein (CRP), the neutrophil-to-lymphocyte ratio (NLR), and the platelet-to-lymphocyte ratio (PLR) to differentiate bacterial and viral etiologies of community-acquired pneumonia (CAP). Methods. A retrospective observational study was conducted at the General Hospital of the Instituto Ecuatoriano de Seguridad Social in Riobamba, Ecuador, between January 2023 and July 2025. A total of 100 patients with CAP and microbiologically confirmed diagnoses were included (50 bacterial and 50 viral cases). Complete blood count parameters and CRP levels were analyzed at admission. Receiver operating characteristic (ROC) curves were constructed for each biomarker, optimal cutoff points were determined, and multivariable logistic regression analysis was performed. Results. The CURB-65 severity score and length of hospital stay were higher in the bacterial CAP group (p < 0.001). NLR, CRP, and PLR values were significantly higher in bacterial pneumonia (p < 0.001). Diagnostic performance was as follows: NLR, AUC = 0.99 (cutoff > 5.85); CRP, AUC = 0.94 (cutoff > 65.55 mg/L); and PLR, AUC = 0.83 (cutoff > 181.7). In multivariable analysis, an NLR > 5.85 was identified as an independent predictor of bacterial etiology (adjusted OR 14.8, 95% CI: 4.20–52.10), along with age (adjusted OR 1.04, 95% CI: 1.01–1.07) and a CURB-65 score ≥ 3 (adjusted OR 5.60, 95% CI: 1.60–19.50). Conclusions. NLR demonstrated the best diagnostic performance, followed by CRP and PLR. These accessible biomarkers may support clinical decision-making and the rational use of antibiotics; however, prospective multicenter validation is required.