Epidemiology of critical illness

Knowledge of the incidence, prevalence, and natural history of disease informs the development of treatments to improve outcomes, the care delivered at the bedside, and the health policy that influences the systems of medical care for critically ill children. In this chapter, we discuss several issues related to clinical epidemiology in critical care and summarize some of the large-scale work that has been done examining the epidemiology of quintessential critical illnesses in children. There are a number of challenges in performing epidemiologic research in critical care, not the least of which is related to a core principle of epidemiology, which is the need to be able to reliably and validly identify diseases or conditions of interest In critical care, definitions of the syndromes that most consider quintessential critical care “diseases” lack gold standard tests by which to validate them. Despite these challenges, researchers have found mortality for many conditions is improving, and the use of ICU services is increasing. Critical care is provided to hundreds of thousands of children in the US annually, and the number and volume of pediatric ICUs has been increasing over the past two decades, to a greater extent than both the US pediatric population and hospital beds for children. Over 7,000 US children are treated for acute lung injury each year, and more than 100,000 infants and older children are mechanically ventilated. Severe sepsis occurs in over 42,000 US children annually, and is a leading cause of death. Rates of ICU care for asthma, the most common chronic disease in childhood, are increasing at the same time that hospitalization rates are decreasing. The thoughtful use of the tools of clinical epidemiology can facilitate advances in pediatric critical care, help us refine their application, and let us understand their ramifications.