Expression and clinical significance of serum C-reactive protein and blood lactate levels in elderly patients with chronic obstructive pulmonary disease complicated by acute lower respiratory tract infection.

objectiveTo evaluate serum C-reactive protein (CRP) and blood lactate levels in elderly patients with Chronic Obstructive Pulmonary Disease (COPD) complicated by acute lower respiratory tract infection (ALRTI).

methodsA total of 265 elderly COPD patients (age ≥ 65 years) were retrospectively analyzed. According to the presence of ALRTI, patients were divided into an ALRTI group (n = 160) and a non-ALRTI group (n = 105). Serum CRP and blood lactate levels were measured within 24 hours of admission.

resultsCompared with the non-ALRTI group, the serum CRP and lactate levels were significantly higher in the ALRTI group (both P < 0.01). Elevated CRP (OR = 3.22) and blood lactate (OR = 2.78) were independent risk factors for ALRTI. Both markers were positively correlated with Confusion, Urea, Respiratory rate, Blood pressure, Age ≥ 65 years (CURB-65) score (r = 0.452 and r = 0.387, both P < 0.001). The area under the receiver operating characteristic (ROC) curve (AUC) for the combination of CRP and lactate in predicting intensive care unit (ICU) admission was 0.835 [95% confidence interval (CI): 0.782-0.888], which was superior to either marker alone.

conclusionSerum CRP and lactate levels are significantly elevated in elderly COPD patients complicated with ALRTI and are associated with disease severity. Their combined detection may improve the identification of high-risk patients and prediction of ICU admission.