Prediction of Mortality Using Hematological and Biochemical Markers in Pneumonia Patients Followed in the Intensive Care Unit: A Retrospective Observational Study

Year 2025, Volume: 7 Issue: 3, 774 - 9, 09.09.2025

Hacer Özlem Kalaycı , Emine Serap Yılmaz , Ahmet Burak Gürpınar

Abstract

Aim: Pneumonia remains a leading cause of mortality among patients admitted to intensive care units (ICUs). The use of hematological and biochemical markers has gained increasing importance in enhancing the accuracy of diagnosis and prognosis. Biomarkers such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), neutrophil-to-platelet ratio (NPR), and the C-reactive protein/albumin ratio, which are calculated using complete blood count parameters, may aid in assessing the severity of systemic inflammation and predicting mortality. Our study examined how NLR, PLR, NPR, and CRP/Albumin ratios affect mortality in ICU patients hospitalized with pneumonia.
Material and Method: This retrospective observational study was conducted at a single center and involved 163 patients diagnosed with pneumonia and admitted to the ICU between May 1, 2021, and March 31, 2025. Demographic data, mortality status, and laboratory parameters at admission were obtained from the hospital information management system. Based on hematological (hemoglobin, neutrophil, lymphocyte, platelet) and biochemical (CRP, albumin) data, NLR, PLR, NPR, and CRP/Albumin ratios were calculated. Patients were categorized into survivors and non-survivors according to 30-day outcomes, and the relationship between the biomarker levels and mortality was analyzed statistically.
Results: A cohort comprising 163 ICU patients diagnosed with pneumonia underwent evaluation, revealing a 30-day mortality rate of 35% (n=57) within this patient population. No significant differences in age or sex were observed between survivors and non-survivors (p>0.05). The CRP levels were significantly lower, while albumin and hemoglobin levels were significantly higher in the survivor group (p<0.05). The CRP/albumin ratio was significantly elevated in non-survivors (p=0.001). Although no statistically significant differences were found for NLR, PLR, and NPR between the groups, these markers tended to be lower in survivors.
Conclusion: According to the findings of our study, low hemoglobin and albumin levels, as well as high CRP levels and CRP/Albumin ratios, were associated with mortality. NLR, PLR and NPR were found to be high in survivors, although not statistically significant. The CRP/Albumin ratio stands out as a reliable biomarker for predicting mortality, whereas NLR, PLR, and NPR, despite their limited sensitivity, may be used as supportive parameters due to their high specificity.

Keywords

Pneumonia , C-reactive protein , neutrophil , lymphocyte , albumin

Ethical Statement

This study was approved by the Clinical Research Ethics Committee of Ordu University (Date: April 11, 2025; Application No: BAEK 128; Decision No: 2025/118).

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