Chronic conditions among children admitted to U.S. pediatric intensive care units: their prevalence and impact on risk for mortality and prolonged length of stay*.

OBJECTIVE: To estimate the prevalence of chronic conditions among children admitted to U.S. pediatric intensive care units and to assess whether patients with complex chronic conditions experience pediatric intensive care unit mortality and prolonged length of stay risk beyond that predicted by commonly used severity-of-illness risk-adjustment models. DESIGN, SETTING, AND PATIENTS: Retrospective cohort analysis of 52,791 pediatric admissions to 54 U.S. pediatric intensive care units that participated in the Virtual Pediatric Intensive Care Unit Systems database in 2008. MEASUREMENTS: Hierarchical logistic regression models, clustered by pediatric intensive care unit site, for pediatric intensive care unit mortality and length of stay >15 days. Standardized mortality ratios adjusted for severity-of-illness score alone and with complex chronic conditions. MAIN
RESULTS: Fifty-three percent of pediatric intensive care unit admissions had complex chronic conditions, and 18.5% had noncomplex chronic conditions. The prevalence of these conditions and their organ system subcategories varied considerably across sites. The majority of complex chronic condition subcategories were associated with significantly greater odds of pediatric intensive care unit mortality (odds ratios 1.25-2.9, all p values < .02) compared to having a noncomplex chronic condition or no chronic condition, after controlling for age, gender, trauma, and severity-of-illness. Only respiratory, gastrointestinal, and rheumatologic/orthopedic/psychiatric complex chronic conditions were not associated with increased odds of pediatric intensive care unit mortality. All subcategories were significantly associated with prolonged length of stay. All noncomplex chronic condition subcategories were either not associated or were negatively associated with pediatric intensive care unit mortality, and most were not associated with prolonged length of stay, compared to having no chronic conditions. Among this group of pediatric intensive care units, adding complex chronic conditions to risk-adjustment models led to greater model accuracy but did not substantially change unit-level standardized mortality ratios.
CONCLUSIONS: Children with complex chronic conditions were at greater risk for pediatric intensive care unit mortality and prolonged length of stay than those with no chronic conditions, but the magnitude of risk varied across subcategories. Inclusion of complex chronic conditions into models of pediatric intensive care unit mortality improved model accuracy but had little impact on standardized mortality ratios.