Data were abstracted from the medical records using a structured data collection form. Documentation that the attending physician was treating the patient for pneumonia was required for further review to occur. Demographic data collected included age, sex, race, and skilled nursing facility residence. Information regarding the presence of at least 1 of a list of comorbid conditions, such as chronic obstructive pulmonary disease, chronic liver disease, chronic renal failure, diabetes mellitus, congestive heart failure, and hospitalization within the past year, was collected. The date and time of arrival, arrival location, date of discharge, and discharge disposition were abstracted. Severity indicators were recorded, including respiratory rate, blood pressure, pulse oximetry reading, PaO2, PaCO2, serum urea nitrogen level, evidence of bilobar or multilobar involvement, need for mechanical ventilation, need for vasopressors, and presence of oliguria or renal failure, as specified by the American Thoracic Society guidelines.6 Information regarding initial diagnostic testing was recorded, including the results of a sputum gram stain, a sputum culture, a blood culture, and serologic tests for atypical pathogens. The results of an initial chest radiograph and thoracentesis, if done, were noted. The timing of the first dose of antimicrobial agent and the choice of agent were recorded.