Initial management decisions for patients with community-acquired pneumonia (CAP) will depend on severity of infection, with need for hospitalization being one of the first decisions. Because empiric antibiotics are the mainstay of treatment and the causative organisms are seldom identified, underlying medical conditions and epidemiologic risk factors are considered when selecting an empiric regimen. As with other infections, duration of therapy is not standardized, but rather is guided by clinical improvement. Prevention of pneumonia centers around vaccination and smoking cessation. This article, the second in a 2-part review of CAP in adults, focuses on site of care decision, empiric and directed therapies, length of treatment, and prevention strategies. Evaluation and diagnosis of CAP are discussed in a separate article.
Site of Care Decision
For patients diagnosed with CAP, the clinician must decide whether treatment will be done in an outpatient or inpatient setting, and for those in the inpatient setting, whether they can safely be treated on the general medical ward or in the intensive care unit (ICU). Two common scoring systems that can be used to aid the clinician in determining severity of the infection and guide site-of-care decisions are the Pneumonia Severity Index (PSI) and CURB-65 scores.
The PSI score uses 20 different parameters, including comorbidities, laboratory parameters, and radiographic findings, to stratify patients into 5 mortality risk classes.1 On the basis of associated mortality rates, it has been suggested that risk class I and II patients should be treated as outpatients, risk class III patients should be treated in an observation unit or with a short hospitalization, and risk class IV and V patients should be treated as inpatients.1
The CURB-65 method of risk stratification is based on 5 clinical parameters: confusion, urea level, respiratory rate, systolic blood pressure, and age ≥ 65 years (Table 1).2,3 A modification to the CURB-65 algorithm tool was CRB-65, which excludes urea nitrogen, making it optimal for making determinations in a clinic-based setting. It should be emphasized that these tools do not take into account other factors that should be used in determining location of treatment, such as stable home, mental illness, or concerns about compliance with medications. In many instances, it is these factors that preclude low-risk patients from being treated as outpatients.4,5 Similarly, these scoring systems have not been validated for immunocompromised patients or those who would qualify as having health care–associated pneumonia.
Patients with CURB-65 scores of 4 or 5 are considered to have severe pneumonia, and admission to the ICU should be considered for these patients. Aside from the CURB-65 score, anyone requiring vasopressor support or mechanical ventilation merits admission to the ICU.6 American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) guidelines also recommend the use of “minor criteria” for making ICU admission decisions; these include respiratory rate ≥ 30 breaths/minute, PaO2 fraction ≤ 250 mm Hg, multilobar infiltrates, confusion, blood urea nitrogen ≥ 20 mg/dL, leukopenia, thrombocytopenia, hypothermia, and hypotension.6 These factors are associated with increased mortality due to CAP, and ICU admission is indicated if 3 of the minor criteria for severe CAP are present.
Another clinical calculator that can be used for assessing severity of CAP is SMART-COP (systolic blood pressure, multilobar chest radiography involvement, albumin level, respiratory rate, tachycardia, confusion, oxygenation and arterial pH).7 This scoring system uses 8 weighted criteria to predict which patients will require intensive respiratory or vasopressor support. SMART-COP has a sensitivity of 79% and a specificity of 64% in predicting ICU admission, whereas CURB-65 has a pooled sensitivity of 57.2% and specificity of 77.2%.8