Assessing pneumonia severity using neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios: a cross-sectional...

Community-acquired pneumonia continues to be a leading cause of morbidity and mortality worldwide. Several validated scoring systems are available for stratifying pneumonia severity, with the CURB-65 being well known. Recently, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been reported as reliable indicators of disease severity and adverse outcomes in patients with pneumonia, particularly when used alongside established scoring systems.

To evaluate the association of NLR and PLR with higher clinical severity classification (CURB-65 ⩾ 3), and to compare their discriminatory performance with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in patients with community-acquired pneumonia.

Cross-sectional study.

In this cross-sectional study conducted at a tertiary care hospital in Peshawar, Pakistan, we enrolled 121 adults with community-acquired pneumonia. Baseline demographic characteristics, comorbid conditions, clinical presentation, and laboratory measures were recorded. Pneumonia severity was assessed using the CURB-65 score. The discriminatory performance of NLR, PLR, CRP, and ESR was evaluated by receiver operating characteristic (ROC) curve analysis, with severe pneumonia defined as a CURB-65 score of 3 or higher. Multivariable logistic regression was performed to assess independent associations after adjustment for age and comorbidities.

The mean (±SD) age of the patients was 59.2 ± 20.6 years, and 69.4% were male. Common comorbidities included diabetes (31.4%), chronic obstructive pulmonary disease (28.1%), and chronic heart failure (19.8%). The mean CURB-65 score was 2.23 ± 1.20. NLR and PLR were significantly higher in severe pneumonia than in non-severe pneumonia (both p < 0.001), whereas CRP and ESR did not differ significantly (p = 0.083 and p = 0.197, respectively). In multivariable analysis, NLR remained independently associated with severe pneumonia (adjusted OR 1.91, 95% CI 1.46-2.51; p < 0.001). In ROC analysis, PLR showed the highest discriminative ability (area under the curve (AUC) 0.9935, 95% CI 0.9847-1.0000), followed by NLR (AUC 0.9436, 95% CI 0.8977-0.9895), CRP (AUC 0.6028, 95% CI 0.4878-0.7178), and ESR (AUC 0.5501, 95% CI 0.4258-0.6744).

In this cohort, NLR and PLR demonstrated strong agreement with higher CURB-65 severity classification and superior discriminatory performance compared with CRP and ESR.