Investigation of systemic inflammation levels in patients followed up with a diagnosis of pneumonia

Aims: Although pneumonia is typically considered a localized infection, it can trigger a systemic inflammatory response. Systemic inflammation is characterized by cytokine release throughout the body, increased acute phase reactants, and immune cell imbalance, which can elevate disease severity and the risk of complications. Recently, hematological parameters such as the systemic immune-inflammation index (SII) and systemic inflammatory response index (SIRI) have gained prominence in assessing this inflammatory response. This study aimed to evaluate systemic inflammation levels in patients diagnosed with pneumonia using SII and SIRI, and to analyze their correlation with classical inflammatory biomarkers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Methods: A total of 50 patients hospitalized and followed up with a diagnosis of pneumonia between 01.01.2023 and 01.06.2025 at Yozgat Bozok University Research and Training Hospital's Departments of Pulmonology and Internal Medicine, and 50 healthy individuals admitted to the same clinics during the same period were included in the study. Demographic data (age, gender), smoking status, clinical histories, laboratory values, treatment processes, complete blood count (CBC), CRP level, and ESR were recorded. Patients with active malignancy, hematological or autoimmune diseases, or those under immunosuppressive therapy were excluded. SII and SIRI values were calculated for each participant. Results: Of the participants, 66% were male and 34% female, with a mean age of 61.98 ± 16.78 years in the pneumonia group and 59.20 ± 16.10 years in the control group. SII was significantly higher in the pneumonia group (1301.28 ± 886.78) compared to the control group (545.20 ± 488.26), as was SIRI (5.66 ± 6.58 vs. 0.91 ± 1.21) (p<0.001 for both). Smokers exhibited significantly higher SII (1535.9 ± 1094.1 vs. 977.2 ± 560.3) and SIRI (7.51 ± 8.13 vs. 3.10 ± 3.72) values than non-smokers (p=0.031 and p=0.014, respectively). Conclusion: This study demonstrated that new-generation inflammation indices such as SII and SIRI reflect the intensity of inflammatory response in pneumonia patients and show significant correlation with CRP levels. These findings suggest that integrating these indices into clinical practice may serve as effective tools in evaluating disease prognosis and monitoring treatment response.