Clinical Application of Blood Lactate, C-Reactive Protein, and the Age-Adjusted Charlson Comorbidity Index in...

The objective of this study is to develop an early warning model that combines the age-adjusted Charlson comorbidity index (aCCI) with serum lactate (Lac) and C-reactive protein (CRP) levels to predict the progression of early methicillin-resistant Staphylococcus aureus (MRSA) pneumonia into severe pneumonia (SP).

This study was a retrospective case-control analysis. Sixty-four inpatients diagnosed with MRSA pneumonia at the First Affiliated Hospital of Soochow University from November 2023 to August 2024 were selected as study subjects. They were divided into two groups: the SP group (SP group) and the non-SP (nSP) group, based on established diagnostic criteria for SP. Demographic, clinical, and laboratory data of the patients were collected and statistically analyzed.

Twenty-four patients (37.5%) developed SP, and the aCCI score was significantly higher in the SP group compared to the nSP group, with a statistically significant difference between the two groups (p  < 0.05). Hospital-associated pneumonia caused by hospital-acquired MRSA (HA-MRSA) was more prevalent in the nSP group (p  < 0.05). However, the differences between the SP and nSP groups were not statistically significant for laboratory indicators such as white blood cell (WBC) count, lymphocyte (LY) count, neutrophil (NE) count, and platelet (PLT) count (p  > 0.05). The levels of CRP and serum Lac in the SP group were significantly higher than those in the nSP group, with statistically significant differences (p  < 0.05). Multifactorial logistic regression analysis indicated that HA-MRSA was an independent protective factor against MRSA-associated SP, while the aCCI score, CRP, and serum Lac levels were identified as risk factors for the progression of MRSA to SP. The combination of these three factors demonstrated good predictive efficacy, with an area under the curve (AUC) of 0.913 (p  < 0.001, 95% CI: 0.841, 0.985).

MRSA strains associated with SP demonstrate a lack of specificity in their clinical manifestations. HA-MRSA is less likely to lead to SP compared to community-acquired MRSA (CA-MRSA). An aCCI score ≥7, in conjunction with elevated levels of early CRP and serum Lac, can serve as effective early indicators that MRSA pneumonia may progress to a severe form.