Moore et al evaluated patients with acute cough associated with a lower respiratory tract infection. They identified clinical findings seen at presentation in patients with pneumonia identified on chest X-ray in the following week. The authors are from the University of Southhampton, University of Oxford and University of Washington in Seattle.
Patient selection: adult with acute cough attributed to a lower respiratory tract infection
Prevalence of pneumonia: 1 in 270
Outcome: evidence of pneumonia in a radiograph performed within the next 7 days (with this group being a higher risk subset including those older, smoker, sicker, and/or positive physical finding; only 2.5% of original group had radiographs with 16% of these showing pneumonia)
Clinical findings at baseline associated with chest X-ray with evidence of pneumonia:
(1) temperature > 37.8°Ct
(2) tachycardia (heart rate > 100 beats per minute)
(3) reduce oxygen saturation (< 95%)
(4) crackles heard on auscultation
None of the findings were present in 34%, with the negative predictive value was 93%. But a subset will be found to have pneumonia.
The presence of 2 or more findings had a sensitivity of 42% but specificity of 81%.
The presence of 3 or more findings had a sensitivity of 19% and specificity of 96%.
If positive these can help to identify high risk patients but relatively insensitive.
