Platelet Count as a Predictor for Community-Acquired Pneumonia Severity Using PSI Score

Abstract

Community-Acquired pneumonia (CAP) refers to the inflammation of the lung parenchyma that is contracted outside of a hospital setting. In addition, in developing countries, it is among the top three causes of death worldwide. Pneumonia severity is often assessed using various instruments, including Pneumonia Severity Index (PSI). Furthermore, the platelet play a crucial role in both hemostasis and the defense of the body against infectious agents. A relatively inexpensive and routinely conducted test, namely the platelet count serves as a supporting examination. Therefore, this study aimed to determine the potential correlation between the platelet count and CAP severity. Aims: The objective of this study was to investigate the potential role of platelet count as a predictive factor for evaluating the severity of CAP patients using PSI scores. Methodology: An analytical observational study with a retrospective cross-sectional design was conducted on patients diagnosed with CAP at Dr. Moewardi General Hospital Surakarta from October 2022 to May 2023. Patients data were extracted from medical records. The correlation between the platelet count and CAP severity was analysed using the Spearman correlation test. The platelet count cut-off value was determined using Receiver Operating Characteristic (ROC) curve. Results: In this study, there were 183 subjects with an average age of 56.90 and a platelet count of 272,688.52 (SD ± 157,524.87). The CAP severity was dominated by the moderate-severe category (52.5%). The platelet count was negatively correlated with severity based on PSI score with p=0.029 (p<0.05) and r=0.162 (low correlation value). Based on ROC curve, AUC value = 0.594 (very weak predictor) and the platelet count cut-off value was 152,000 (sensitivity = 0.322, specificity = 0.91). Scientific Novelty: There is a correlation between the platelet count and the severity of CAP based on the PSI score. Conclusion: A significant correlation was found between the platelet count and CAP severity based on PSI score. However, the platelet count could not be used as a reliable predictor of CAP severity.