Supporting Evidence. Data from retrospective, prospective observational, and prospective intervention trials support the preceding criteria for switching from parenteral to oral antibiotics for patients with community-acquired pneumonia. A prospective observational study showed that clinical deterioration requiring admission to an intensive care, coronary care, or telemetry unit occurred in 1% or fewer cases once clinical stability was reached (47). Clinical stability was defined in five ways. The most “lenient” definition included heart rate less than or equal to 100 beats/min, systolic blood pressure of 90 mm Hg or greater, respiratory rate less than or equal to 24 breaths/min, oxygen saturation greater than or equal to 90%, temperature less than or equal to 38.3 °C (101 °F), ability to eat, and normal mental status. The other four definitions differed only in terms of respiratory rate, oxygen saturation, and temperature. The most conservative definition described a respiratory rate less than or equal to 20 breaths/min, oxygen saturation greater than or equal to 94%, and temperature less than or equal to 37.2 °C (99 °F). Two other prospective observational studies (48–49), one of which was published after the development of the indicators , demonstrated that early switching to oral antibiotics was reasonable for hospitalized patients with community-acquired pneumonia who met the following criteria: 1) resolution of fever, 2) improvement of cough and respiratory distress, 3) improvement of leukocytosis, and 4) presence of normal gastrointestinal tract absorption.