The Pneumonia Severity Index (PSI) is a validated predictor of all-cause mortality at 30 days. The initial assessment determines the presence of 11 variables associated with adverse outcomes. Patients with no risk factors (severity risk class I) can typically be managed as outpatients. Those with at least one risk factor are stratified using a second scoring system into a risk classification between II and V based on a more complex point system that includes residence in a nursing home, abnormal laboratory test results, and radiographic findings. The PSI is recommended over the CURB-65 score.