What signs and symptoms are most useful for excluding the diagnosis of pneumonia in community-dwelling adults with an acute respiratory infection?

Community-dwelling adults who present to a primary care office with acute respiratory infection symptoms but normal vital signs and normal findings on a pulmonary examination have only a 0.4% likelihood of community-acquired pneumonia (CAP). (LOE = 1a)

Marchello CS, Ebell MH, Dale AP, Harvill ET, Shen Y, Whalen CC. Signs and symptoms that rule out community-acquired pneumonia in outpatient adults: A systematic review and meta-analysis. J Am Board Fam Med 2019;32(2):234-247.  [PMID:30850460]

Systematic review

Self-funded or unfunded

Various (meta-analysis)

Identifying signs and symptoms that reliably rule out CAP may help reduce the overuse of radiography and/or laboratory testing. These investigators systematically searched MEDLINE and reference lists of pertinent articles for studies that used a clinical decision rule to diagnose CAP in the outpatient setting. Eligible criteria included the use of either a chest x-ray or computed tomography as the reference standard for either all enrolled patients or a random/systematic sample of the enrolled patients. In addition, only studies that recruited adults or adolescents in an outpatient setting, including the emergency department, were included. Two individuals independently reviewed potential studies for inclusion criteria and methodologic quality using standard criteria. The resolution of any disagreements occurred after consensus discussion with a third reviewer. A total of 12 studies met inclusion criteria, of which 6 were performed in an emergency department setting and 6 in a primary care setting. Sample sizes ranged from 246 to 2820 patients. Six studies were found to be at low risk of bias; the remaining 6 were at moderate risk of bias. The combination of normal vital signs (temperature, respiratory rate, and heart rate) plus normal findings on the pulmonary examination reliably excluded CAP (sensitivity = 0.96; 95% CI 0.92 - 0.28; negative likelihood ratio = 0.10; 0.07 - 0.13).