Diagnostic value of C reactive protein in infections of the lower respiratory tract: systematic review

Abstract

Objectives 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. Data sources Medline and Embase (January 1966 to April 2004), with reference checking. Study selection 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. Conclusion 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.

Sputum colour and bacteria in chronic bronchitis exacerbations: a pooled analysis

“…Perhaps the inclusion of patients with type III exacerbations would have made this difference more evident. In multivariate analysis, CRP was not predictive of the presence of a PPM in sputum; in a systematic review, testing for CRP was consistently neither sufficiently sensitive to rule out nor sufficiently specific to rule in an infiltrate on chest radiography and a bacterial aetiology of lower respiratory tract infection [27]. In the field of biomarkers, measurement of procalcitonin level shows promise as a means of identifying patients with exacerbations of COPD who require antimicrobial treatment [28].…”

Cost-Effectiveness of Procalcitonin-Guided Antibiotic Therapy for Outpatient Management of Acute Respiratory Tract Infections in Adults

“…14,15 More recently, procalcitonin has emerged as a promising alternative for guiding antibiotic therapy, because this serum marker is elevated in bacterial infections, but not in viral infections or non-specific inflammatory reactions. 16 Procalcitonin has been studied in ambulatory and emergency department settings for guiding antibiotic therapy in adults with ARTIs and been found to reduce antibiotic use and treatment duration without increasing morbidity or mortality.…”

FebriDx Point-of-Care Testing to Guide Antibiotic Therapy for AcuteRespiratory Tract Infection in UK Primary Care: A Retrospective OutcomeAnalysis

“…Improving diagnostic certainty may help identify those patients that will benefit from antibiotic treatment [16][17][18]. A meta-analysis that looked at 13 studies of upper respiratory tract infection (URI) and lower respiratory tract infection (LRTI) on the association between point-of-care (POC) C-reactive protein (CRP) testing and antibiotic prescribing for ARTIs in general practice found that CRP testing significantly decreased antibiotic prescribing at the initial consultation [19].…”