Elevated Lactate, D-dimer, and IL-6 Associated with Elderly Community-Acquired SARS-CoV-2 Pneumonia Severity

Uncontrolled systemic inflammatory responses significantly contribute to the pathogenesis of severe community-acquired pneumonia (CAP) following SARS-CoV-2 infection (CASP). Elderly populations, being particularly vulnerable to respiratory infections, demonstrate both increased susceptibility to SARS-CoV-2 infection and greater disease severity. This study aimed to identify readily available routine hematological biomarkers that could serve as independent risk factors for predicting severe CASP (sCASP) in elderly patients.

A retrospective study was conducted to analyze 77 elderly people with CASP. According to the severity of the disease, the elderly people were divided into a non-sCASP group and a sCASP group, and the routine comprehensive laboratory examinations were compared.

A total of 77 elderly patients with CASP were enrolled in this study, comprising 35 cases in the non-sCASP group and 42 cases in the sCASP group. Significant differences were observed in admission laboratory parameters, including routine blood counts, coagulation profiles, liver and kidney function tests, inflammatory markers, and composite laboratory-derived indices, between non-sCASP and sCASP cases infected with SARS-CoV-2 Omicron subvariants BA.5.2 and BF.7 (p < 0.05). Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses identified lactate > 1.95 mmol/L, D-dimer > 0.85 mg/L, and IL-6 > 33.5 pg/mL as the most probable independent risk factors for sCASP in elderly patients. Notably, the combined diagnostic model (lactate-D-dimer-IL-6) demonstrated superior predictive performance for disease severity (AUC = 0.981; 95% CI: 0.954 - 1) compared to any single biomarker alone.

Elevated admission lactate, D-dimer, and IL-6 can be used as independent risk factors for the evaluation of CASP severity in elderly people, and the joint detection might be a better choice. This is imperative for guiding the development of effective interventions to alleviate severe patients' symptoms and burden.