Diagnostic value of C reactive protein in infections of the lower respiratory tract: systematic review.
OBJECTIVE
To evaluate the diagnostic accuracy of C reactive protein in detecting radiologically proved pneumonia and to evaluate how well it can discriminate between bacterial and viral infections of the lower respiratory tract.


METHODS
Medline and Embase (January 1966 to April 2004), with reference checking.


METHODS
We included articles comparing C reactive protein with a chest radiograph or with microbiological work-up as a reference test. Two authors independently assessed methodological items.


RESULTS
None of the studies met all validity criteria. Six studies used an infiltrate on chest radiograph as reference test. Sensitivities ranged from 10% to 98%, specificities from 44% to 99%. For adults, the relation of C reactive protein with an infiltrate (in a subgroup analysis of five studies) showed an area under the curve of 0.80 (95% confidence interval 0.75 to 0.85). In 12 studies, the relation of C reactive protein with a bacterial aetiology of infection of the lower respiratory tract was studied. Sensitivities ranged from 8% to 99%, specificities from 27% to 95%. These data were epidemiologically and statistically heterogeneous, so overall outcomes could not be calculated.


CONCLUSIONS
Testing for C reactive protein is neither sufficiently sensitive to rule out nor sufficiently specific to rule in an infiltrate on chest radiograph and bacterial aetiology of lower respiratory tract infection. The methodological quality of the diagnostic studies is generally poor. The evidence not consistently and sufficiently supports a wide introduction of C reactive protein as a rapid test to guide antibiotics prescription.
van der Meer
Victor
V
Leiden University Medical Center, Albinusdreef 2, PO Box 9600, 2300 RC, Leiden, Netherlands. V.van_der_Meer@lumc.nl
Neven
Arie Knuistingh
AK
van den Broek
Peterhans J
PJ
Assendelft
Willem J J
WJ
D019540:Area Under Curve; D002097:C-Reactive Protein / Q000032:analysis*; D006801:Humans; D018410:Pneumonia, Bacterial / Q000175:diagnosis*; D011024:Pneumonia, Viral / Q000175:diagnosis*; D011786:Quality Control; D012680:Sensitivity and Specificity
D002097:C-Reactive Protein