Diagnostic characteristics of C reactive protein (CRP) (mg/l) and erythrocyte sedimentation rate (ESR) (mm/h) tests for diagnosing pneumonia in lower respiratory tract infection*
| Tests | Sensitivity (95% CI) | Specificity (CI) | +LR | −LR |
|---|---|---|---|---|
| *Diagnostic terms defined in glossary. Sensitivity, specificity, and CIs provided by author; LRs calculated from data provided by author. | ||||
| CRP ⩾10 | 97% (84 to 100) | 31% (25 to 38) | 1.4 | 0.10 |
| CRP ⩾20 | 91% (75 to 98) | 51% (44 to 57) | 1.8 | 0.19 |
| CRP ⩾50 | 88% (71 to 97) | 75% (70 to 81) | 3.6 | 0.17 |
| ESR ⩾10 | 97% (84 to 100) | 29% (23 to 35) | 1.4 | 0.11 |
| ESR ⩾20 | 78% (60 to 91) | 57% (51 to 63) | 1.8 | 0.38 |
| ESR ⩾40 | 59% (41 to 76) | 85% (80 to 90) | 3.9 | 0.48 |