Risk factors for complicated varicella infection in pediatric oncology patients at a tertiary health care facility in Pakistan

Introduction: Varicella zoster infection(VZI) is well recognized as a potential cause of morbidity and mortality in immunocompromised pediatric oncology patients (POP). The purpose of this study was to describe the clinical profile and risk factors for complications and outcomes of VZI in POP treated with acyclovir. Methodology: Medical records of all POP with a discharge diagnosis of VZI over a period of seven years (2005-2011) were reviewed. The demographic features, underlying malignancy, risk factors for VZI, complications, and outcomes were recorded. Results: Thirty-six POP with VZI were identified. Leukemia was the most common underlying malignancy (n = 20, 58.8%), followed by lymphoma (n = 7, 20.6%) and solid organ tumors (n = 7, 20.6%). Most of the cases (41%) were observed in children under five. All patients were treated with acyclovir. Varicella-related complications developed in 10 (29%) patients. The most frequent complication was bloodstream infection (n = 3, 8.8%), followed by pneumonia (n = 2, 5.9%), skin infection (n = 2, 5.9%), hepatitis, renal failure, and encephalitis. Independent risk factors associated with complications were age < five years, weight for age < fifth percentile, delay in seeking care (> seven days after onset of symptoms) and severe neutropenia (ANC < 500/cm). One child died secondary to varicella encephalitis. Conclusion: Our data suggests that young age, poor health-seeking behavior, severe neutropenia, and being underweight are the major risk factors for the development of varicella-related complications in POP in developing countries. These complications could be favorably modified through active immunization of immunocompetent children.