Risk stratification for patients with community-acquired pneumonia.

Community-acquired pneumonia (CAP) is a common medical illness with a prognosis that ranges from rapid complete recovery to severe medical complications and death. Approximately 4 million adults are diagnosed with CAP in the US each year; with more than 600,000 (15%) hospitalised. An estimated $4 billion is expended annually on patients with CAP, with inpatient therapy costing as much as 20 times that of outpatient antimicrobial therapy. Determining severity of illness and using this information to risk-stratify patients with CAP is important from several perspectives. Clinically, understanding prognosis can assist physicians in the initial site of treatment decision (home versus hospital) and can be used to communicate expected outcomes to patients. From a research perspective, risk stratification can be used to select appropriate patient subgroups for clinical trials and to provide severity-adjusted outcomes comparisons. From a policy perspective, severity-adjusted outcomes can be used as a proxy for quality of medical care.