Decision analysis and clinical uncertainty.

: Decision analysis is a tool to aid decision-making in the face of uncertainty. Typically, clinical decision-making involves the selection of one or more therapeutic alternatives when the outcome of that decision cannot fully be known at the time the decision must be made. Uncertainty derives from imperfections in diagnostic testing, uncertainty about the natural history of disease, the random nature of iatrogenic complications, and the impact of patient-specific factors or comorbid conditions. Decision analysis seeks to optimize the expected outcome of a decision, incorporating the probabilistic nature of this uncertainty. Decision analysis is applied here to a common problem in intensive care units-the treatment of suspected ventilator-associated pneumonia. Recent applications of decision analysis in the pediatric literature are also used to illustrate the scope and limitations of this tool in clinical practice.