Seventeen diagnostic accuracy studies were included in the review, of which 13 provided quantitative data and were included in the analysis: 6 studies provided data for the evaluation of the diagnostic accuracy of C reactive protein in detecting radiologically proved pneumonia (1,178 patients) and 8 studies provided data for the assessment of how well C reactive protein can discriminate between bacterial and viral infections of the lower respiratory tract (1,096 patients). One of the studies was included for both questions.
The initial agreement between reviewers for the quality assessment was 82.5% (k=0.68).
Diagnostic accuracy of C reactive protein in detecting radiologically proved pneumonia.
The sensitivities ranged from 10 to 98% and the specificities from 44 to 99%. The area under the sROC curve for the subgroup of adults (5 studies) was 0.80 (95% confidence interval, CI: 0.75, 0.85). Other subgroup analyses were not performed because of a lack of data. Sensitivity analysis of the areas under the curves of studies that met the four quality criteria (area under the curve 0.84, 95% CI: 0.78, 090) and those that did not meet the criteria (area under the curve 0.74, 95% CI: 0.65, 0.83) showed robustness of the data.
Discrimination between bacterial and viral infections.
The sensitivities ranged from 8 to 99% and the specificities from 27 to 95%. An sROC curve for the subgroup of children (6 studies) could not be drawn because of statistical heterogeneity. Other subgroup analyses were not performed because of a lack of data. None of the studies met the four quality criteria, therefore a sensitivity analysis was not performed for methodological quality.