Admission is not always necessary for patients with community-acquired pneumonia in risk classes IV and V diagnosed in the emergency room.

OBJECTIVE: To determine the factors that allow patients with community-acquired pneumonia who are at high risk of mortality (risk classes IV and V) to be treated at home.

DESIGN: A prospective, observational study.

SETTING: Six hospitals and one free-standing emergency room in Edmonton, Alberta.

PARTICIPANTS: The present study included 2354 patients in risk classes IV and V who had a diagnosis of pneumonia made by an emergency room physician or an internist.

MEASUREMENTS: Symptoms, signs and laboratory findings, as well as outcome measures of length of stay and mortality.

RESULTS: Of the total study group, 319 of the patients (13.5%) were treated on an ambulatory basis. Factors predictive of admission were definite or possible pneumonia on chest radiograph as read by a radiologist, functional impairment, altered mental status, substance abuse, psychiatric disorder, abnormal white blood cell count, abnormal lymphocyte count, oxygen saturation less than 90% and antibiotic administration in the week before admission. If chest pain was present, admission was less likely. Only two of the 319 patients required subsequent admission (both had positive blood cultures) and only two died.

CONCLUSIONS: A substantial number of patients in risk classes IV and V can be safely treated at home. Factors that help clinicians to select this subset of patients are discussed.