The clinical analysis and indications for exchange transfusion in 158 children with pertussis characterized by marked leukocytosis.

BACKGROUND

Hyperleukocytosis (WBC ≥ 30 × 10⁹/L) strongly associated with fatal outcomes; evidence-based thresholds for initiating exchange transfusion (ET) remain undefined. This study aims to investigate the association between leukocyte elevation and disease severity, and define evidence-based thresholds for initiating exchange transfusion, to assist clinical doctors in determining evidence-based medical indications for ET therapy in pediatric patients with pertussis exhibiting marked leukocytosis (WBC ≥ 30 × 10⁹/L).

METHODS

We conducted a retrospective cohort study involving 158 children diagnosed with pertussis, who were stratified into three groups based on peak WBC levels: Group A (30-50 × 10⁹/L), Group B (50-70 × 10⁹/L), and Group C (≥ 70 × 10⁹/L). Clinical parameters, including cardiorespiratory indices, complications, and treatment outcomes, were analyzed using the Kruskal-Wallis test and ROC curve analyses.

RESULTS

Significant differences were observed across the WBC strata in clinical severity markers: cyanosis (45% vs. 58.2% vs. 78.3%, P = 0.015), fever (41.3% vs. 60% vs. 91.3%, P < 0.001), peak respiratory rate (53.9 ± 11.46 vs. 59.4 ± 12.33 vs. 69.04 ± 14.08 breaths/min, P < 0.001), and peak heart rate (144 vs. 157 vs. 187.5 bpm, P < 0.001). Mortality rates escalated with leukocytosis (0% vs. 3.6% vs. 43.5%, P < 0.001).ROC analysis identified optimal thresholds for predicting the need for ET: WBC > 55.38 × 10⁹/L (AUC = 0.899, 95% CI 0.834-0.963; sensitivity 88.2%, specificity 23.4%),Respiratory rate ≥ 59 breaths/min (AUC = 0.795; 95%CI 0.699 ~ 0.891, sensitivity 94.1%, specificity 36.7%),Heart rate ≥ 159 bpm (AUC = 0.813; 95%CI 0.731 ~ 0.895,sensitivity 100%, specificity 38.1%). Patients who met these thresholds required prolonged ICU stays (median 16 vs. 9 days, P = 0.011) and exhibited higher rates of mechanical ventilation (82.6% vs. 7.7%, P < 0.001).

CONCLUSION

Leukocyte levels are strongly correlated with the severity of pertussis, risks of complications, and mortality. We propose initiating ET when WBC exceeds 55 × 10⁹/L, particularly in conjunction with tachypnea (> 60 breaths/min) or tachycardia (> 160 bpm), to mitigate the risk of life-threatening outcomes.