[The Clinical Value of Neutrophil CD64 Index in Hematological Malignancies with Pulmonary Infection]

Objective: To investigate the clinical value of neutrophil CD64 index in hematological malignancies with pulmonary infection.

Methods: The cohort study method was used to retrospectively analyze the clinical data of 125 patients with hematological malignancies and pulmonary infections who were treated in The Third Affiliated Hospital of Soochow University. All the patients were divided into four stages according to the diagnosis and treatment process: non-infected stage (T1), the symptoms of infection had appeared before using antibiotics (T2), one week after anti-infective treatment (T3), and after stopping antibiotics (T4). CD64 index, C-reactive protein (CRP), blood cell count, and immune cell level were compared before and after infection (T1 vs T2), the correlation between CD64 index and other indicators were explored, the change trends of the significantly different indicators in the course of the disease were observed, and the diagnostic efficacy of CD64 index and CRP were compared. The surviving patients were followed up for whether reinfection occurred within 30 days after discharge, and the re-examination results of indices before discharge (in stage of T4) between reinfected and non-reinfected patients were compared to find the risk factors of reinfection.

Results: Before and after infection, the CD64 index, CRP, CD14⁺HLA-DR⁺, CD4⁺, and lymphocyte counts were significantly different (all P<0.05). There was a negative correlation of CD64 index with CD14⁺HLA-DR⁺ (r=-0.395, P<0.001), a negative correlation with CD3⁺ (r=-0.1.87, P=0.047), and a negative correlation with lymphocyte count (r=-0.230, P=0.006), while a positive correlation with CRP(r=0.313, P<0.001). The area under the curve of CD64 index, CRP, and CD64 index combined with CRP was 0.790 (95%CI: 0.711-0.868), 0.754(95%CI: 0.667-0.841), and 0.835(95%CI: 0.762-0.907), respectively; the sensitivity was 59.6%, 72.7%, and 74.7%, the specificity was 89.2%, 73.0%, and 78.4%, and the cut-off value was 0.488, 0.457, and 0.531, respectively. There were only two re-examination indexes showed significantly different before discharge between reinfected patients and non-reinfected patients: CD14⁺HLA-DR⁺ (F=8.524, P=0.004) and CD64 index (F=9.993, P=0.002). The increase of CD64 index was an independent risk factor for reinfection within 30 days after discharge from the hospital (HR=1.790, 95%CI: 1.343-2.386, P<0.001).

Conclusion: CD64 index has diagnostic value in patients with hematological malignancies and pulmonary infection, and its specificity is higher than that of CRP. The combination of the two indicators can improve the diagnostic sensitivity. CD64 index has a predictive value for reinfection within 30 days after infection treatment.