Clinical phenotypes and mortality predictors in pediatric critical pertussis: A multinational study

Area of Science:

• Pediatric Critical Care Medicine
• Infectious Diseases
• Epidemiology

Background:

• Critical pertussis (whooping cough) presents a high mortality risk, with early risk stratification remaining a significant challenge.
• While hyperleukocytosis and pulmonary hypertension (PHT) are associated with adverse outcomes, the prognostic value of white blood cell (WBC) count trajectories and optimal treatment thresholds are not well-defined.
• This study aimed to identify mortality predictors and characterize WBC dynamics in children with pertussis admitted to pediatric intensive care units (PICUs).

Purpose of the Study:

• To identify predictors of mortality in pediatric intensive care unit (PICU) patients with critical pertussis.
• To characterize white blood cell (WBC) count dynamics and establish an optimal WBC threshold for treatment intervention.
• To stratify clinical presentations and outcomes based on disease phenotype.

Main Methods:

• A retrospective cohort study was conducted across 35 PICUs in six Gulf Cooperation Council countries from July 2022 to December 2024.
• Data included demographic and clinical information, with WBC counts recorded at emergency presentation, PICU admission, and peak values.
• Logistic regression analyzed mortality predictors, while ROC curves and the Youden Index determined the optimal WBC threshold for mortality prediction.

Main Results:

• The study included 204 children, with a mortality rate of 15.2%. Non-survivors were younger and had shorter symptom duration, requiring more frequent leukoreduction, inotropic support, and nitric oxide therapy.
• Independent predictors of mortality included underweight status (aOR 7.59), PHT (aOR 3.69), elevated day-1 PELOD score (aOR 1.32), and peak WBC count (aOR 1.05).
• Peak WBC count demonstrated strong discrimination for mortality (AUC 0.86) with an optimal threshold of 51.5 × 10⁹/L. Two phenotypes, apnea and respiratory distress (RD), were identified, with the RD group showing higher WBC, PHT, PICU stays, and mortality.

Conclusions:

• Mortality in critical pertussis remains high, underscoring the need for improved risk stratification and management strategies.
• Underweight status, illness severity at presentation, peak WBC count, and PHT are significant determinants of poor outcomes in pediatric pertussis.
• Phenotype stratification reveals distinct clinical presentations, suggesting tailored treatment approaches may be beneficial.