Correspondence: Margaretha C. Minnaard, University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Stratenum 6.118, PO Box 85500, 3508 GA Utrecht, The Netherlands. Tel: + 31 88 7568620 or + 31 65 1339685. Fax: + 31 88 7568099. E-mail: m.c.minnaard@umcutrecht.nl (Received 2 June 2014; accepted 7 January 2015) ORIGINAL ARTICLE The added diagnostic value of five different C-reactive protein point-of-care test devices in detecting pneumonia in primary care: A nested case-control study MARGARETHA C. MINNAARD 1 , ALMA C. VAN DE POL 1 , JORIS A. H. DE GROOT 1 , NIEK J. DE WIT 1 , ROGIER M. HOPSTAKEN 2 , SANNE VAN DELFT 2 , HERMAN GOOSSENS 3 , MARGARETA IEVEN 3 , CHRISTINE LAMMENS 3 , PAUL LITTLE 4 , CHRIS C. BUTLER 5 , BERNA D. L. BROEKHUIZEN 1 & THEO J. M. VERHEIJ 1 1 University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht, the Netherlands, 2 Saltro, Diagnostic Center for Primary Care, Utrecht, the Netherlands, 3 University of Antwerp,Laboratory of Medical Microbiology,Vaccine & Infectious Diseases Institute (VAXINFECTIO), Antwerp, Belgium, 4 University of Southampton Medical School, Primary Care Medical Group, Southampton, UK, and 5 Institute of Primary Care and Public Health, Cardiff University ,Wales, UK Abstract Background. The results obtained from various point-of-care (POC) test devices for estimating C-reactive protein (CRP) levels in a laboratory setting differ when compared to a laboratory reference test. We aimed to determine whether such differences meaningfully affect the accuracy and added diagnostic value in predicting radiographic pneumonia in adults presenting with acute cough in primary care. Methods. A nested case control study of adult patients presenting with acute cough in 12 different European countries (the Genomics to combat Resistance against Antibiotics in Community-acquired LRTI in Europe [GRACE] Network). Venous blood samples from 100 patients with and 100 patients without pneumonia were tested with five different POC CRP tests and a laboratory analyzer. Single test accuracy values and the added value of CRP to symptoms and signs were calculated. Results. Single test accuracy values showed similar results for all five POC CRP tests and the laboratory analyzer. The area under the curve of the different POC CRP tests and the laboratory analyzer (range 0.79–0.80) were all comparable and higher than the clinical model without CRP (0.70). Multivariable odds ratios were the same (1.2) for all CRP tests. Conclusions. Five POC CRP test devices and the laboratory analyzer performed with similar accuracy in detecting pneumonia both as single test, and when used in addition to clinical findings. Variability in results obtained from standard CRP laboratory and POC test devices do not translate into clinically relevant differences when used for prediction of pneumonia in patients with acute cough in primary care. Key Words: C-reactive protein, point-of-care testing, primary health care, lower respiratory tract infections, diagnostic tests Introduction C-reactive protein (CRP) is an acute phase protein synthesized by the liver in response to inflammation. CRP helps identify patients at high or low risk of pneumonia [1–6]. CRP point-of-care (POC) testing is attractive to clinicians as results can be available within 4 minutes and thus results can alter manage- ment decisions during the patient’ s first presentation. Currently, there are several POC CRP devices avail- able, but studies directly comparing these systems are scarce. In a comparative laboratory study using anonymous routine blood samples we found variabil- ity between the POC CRP devices compared to results obtained from a conventional laboratory ana- lyzer [7]. However, the extent to which variability of POC CRP test results translates into differences in accuracy to detect the clinical target condition pneu- monia is unknown. Furthermore, accuracy of the Scandinavian Journal of Clinical & Laboratory Investigation, 2015; Early Online: 1–5 ISSN 0036-5513 print/ISSN 1502-7686 online © 2015 Informa Healthcare DOI: 10.3109/00365513.2015.1006136 Scand J Clin Lab Invest Downloaded from informahealthcare.com by University Library Utrecht on 03/23/15 For personal use only.