Prevalence and Outcomes of Primary Immunodeficiency in Hospitalized Children in the United States

BACKGROUND: Primary immunodeficiency diseases (PIDDs) are rare yet life-threatening chronic conditions in children. The prevalence and outcomes of PIDDs in the pediatric population in the United States are not well understood. OBJECTIVE: The objectives of this study were to (1) determine the epidemiology of children hospitalized with PIDD in the United States and (2) characterize the clinical outcomes of hospitalized children with PIDDs. METHODS: Retrospective cohort analysis of the 2003-2012 Kids' Inpatient Database of children aged 2-18 years admitted with a primary or secondary diagnosis code of PIDD was performed. Secondary immunodeficiency diseases were excluded. RESULTS: There were 26,794 pediatric patients hospitalized with a diagnosis of a PIDD from 2003 to 2012. The national prevalence of all PIDDs per 100,000 was 66.6, 82.2, 97.4, and 126.8 in 2003, 2006, 2009, and 2012, respectively. The highest prevalence was in children 0-5 years of age (15,105 hospitalizations; 56%). There was no difference in prevalence between B-cell defects and T-cell defects. PIDDs affected all ethnic populations equally. Respiratory-related diagnoses were the most common comorbidity by an organ system. Overall mortality was 1.99%. Age was inversely correlated with clinical outcome. Children 0-5 years had higher mortality (424 deaths, 79.85%), mean hospital charges ($ 35,480), and length of stay (LOS) (5.6 days) compared with older age cohorts. CONCLUSIONS: The prevalence of PIDDs in the hospitalized pediatric population in the United States may have increased over time. Younger age is associated with higher mortality, hospital costs, and LOS. Further study is needed to determine cost-effective management strategies to improve outcomes in infants and young children with PIDD. (C) 2017 American Academy of Allergy, Asthma & Immunology