Etiologies and Clinical Outcomes of Patients With Secondary Hemophagocytic Lymphohistiocytosis at a Tertiary PICU.

OBJECTIVES

To assess the etiologies and outcomes of patients with secondary hemophagocytic lymphohistiocytosis in the PICU.

DESIGN

Prospective observational cohort study.

SETTING

A single PICU at a pediatric tertiary hospital in Hanoi, Vietnam.

PATIENTS

Pediatric patients meeting the criteria for secondary hemophagocytic lymphohistiocytosis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Between June 2017 and May 2018, 25 consecutive patients with a mean (SD) age of 23.3 months (21.6 mo) were included. Collected variables included etiologies of hemophagocytic lymphohistiocytosis and clinical and laboratory findings at admission. The Pediatric Index of Mortality 2 score at admission was calculated. Outcomes were death and multiple organ dysfunction. The severity of multiple organ dysfunction was assessed by the Pediatric Logistic Organ Dysfunction 2 score. The mean (SD) Pediatric Index of Mortality 2 predicted mortality rate was 5.6% (7.6%). Cytomegalovirus and Epstein-Barr virus coinfections (60%) were the most common suspected etiology of hemophagocytic lymphohistiocytosis. Other etiologies included Epstein-Barr virus sole infections (20%), cytomegalovirus sole infections (16%), and one unknown cause (4%). Multiple organ dysfunction (excluding hematologic failure) was found in 22 patients (88%) with death occurring in 14 patients (56%). The mean (SD) Pediatric Logistic Organ Dysfunction 2 predicted mortality rate among patients with multiple organ dysfunction was 11.9% (11.2%). Despite having lower Pediatric Index of Mortality 2 predicted mortality rates at admission, Epstein-Barr virus-cytomegalovirus coinfection cases with multiple organ dysfunction had slightly greater Pediatric Logistic Organ Dysfunction 2 predicted mortality rates than Epstein-Barr virus sole infection cases with multiple organ dysfunction: 12.2% (10.5%) versus 11.3% (11.0%). However, these rates were lower than cytomegalovirus sole infection cases with multiple organ dysfunction (14.4% [16.3%]). Area under the curve values for Pediatric Index of Mortality 2 and Pediatric Logistic Organ Dysfunction 2 were 0.74 (95% CI, 0.52-0.95) and 0.78 (95% CI, 0.52-1.00), respectively, suggesting that both scales were fair to good at predicting mortality.

CONCLUSIONS

Viral infections, particularly Epstein-Barr virus-cytomegalovirus coinfections, were a common cause of secondary hemophagocytic lymphohistiocytosis. The implication of these coinfections on the clinical course of hemophagocytic lymphohistiocytosis needs to be delineated.