Objective  To investigate the relationships of serum procalcitonin (PCT), α1-acid glycoprotein (α1-AGP) and cluster of differentiation 64 (CD64) index with the severity of illness and prognosis in patients with pulmonary Candida infection after lung cancer surgery.

Methods  A prospective study was conducted in 120 patients with pulmonary Candida infection after lung cancer surgery as infection group, and 60 patients without infection after lung cancer surgery in the same period were selected as control group. Baseline characteristics and laboratory indicators were compared between the two groups. Differences in serum PCT, α1-AGP, CD64 index in peripheral blood, and plasma 1, 3-β-D glucan test (BG) were compared among patients with different severities of illness and prognoses in the infection group. The relationship between serum indicators and prognosis as well as their predictive efficiencies were analyzed, and external validation was performed.

Results  The levels of serum PCT, α1-AGP, CD64 index in peripheral blood, and plasma BG in the infection group were significantly higher than those in the control group (P < 0.05). In the infection group, the levels of serum PCT, α1-AGP, and CD64 gradually decreased significantly in patients with severe, moderate, and mild illness, and the levels of these indicators in dead patients were significantly higher than those in surviving patients (P < 0.05). Survival curve analysis showed that patients with low levels of serum PCT, α1-AGP, and CD64 index before treatment had higher survival rates than those with high levels of these indicators. Receiver operating characteristic (ROC) curve analysis revealed that the combined prediction of PCT, α1-AGP, and CD64 index for mortality was superior to individual indicators or their pairwise combinations, and external validation confirmed the good predictive efficacy of the combined prediction.

Conclusion  PCT, α1-AGP, and CD64 index are closely related to pulmonary Candida infection after lung cancer surgery, and the combined detection of these indicators has certain predictive value for 28-day prognosis.