Evaluating the QuikRead® C-reactive protein test as a point-of-care test

Abstract

Background: Available tests to diagnose infection in neonates often provide results after 12–24 hours. A bedside test that is reliable will facilitate earlier exclusion or diagnosis of infection.

Objective: To validate a bedside C-reactive protein (CRP) test against the currently available laboratory CRP test in neonates with suspected sepsis.

Methods: This was a prospective observational study where a bedside CRP was done concurrently with and validated against a laboratory CRP in neonates with suspected sepsis. The sensitivities, specificities and predictive values for the bedside CRP tests were calculated using the laboratory CRPs as the reference test.

Results: There were 209 measured CRP-sample pairs. Seventy per cent of these had suspected early-onset neonatal sepsis and 30% had suspected late-onset neonatal sepsis. Twelve per cent had culture-proven sepsis. At the recommended cut-off of 8·0 mg/L for the bedside CRP test, the sensitivity, specificity, positive and negative predictive values were 84%, 80%, 30% and 97%, respectively. Adjusting the cut-off value from 8·0 to 15·0 mg/L improved the specificity to 88%. The sensitivity, specificity and positive and negative predictive values were not different between early-onset and late-onset sepsis. The receiver operating characteristic curve had an area below the curve of 0·84 for the cut-off at 16·2 mg/L on the beside CRP test.

Conclusions: The bedside CRP test may be used as a screening test to aid decisions to either commence or discontinue antibiotics in circumstances where the clinical diagnosis of sepsis is in doubt. By using a cut-off of 16·0 mg/L for the bedside CRP test, the possibility of a false negative result is minimised.

Keywords:

• Acute phase reactant
• C-reactive protein
• Diagnostic tool
• Neonatal sepsis
• Point-of-care test
• QuikRead ® CRP test

We thank Sue Holyoak from Allerco, South Africa who represent Orion Diagnostica, Espoo, Finland for lending the QuikRead® 101 instrument and for sponsoring the test kits. We also especially thank our colleagues in neonatal care for their contribution to this paper, Mr Mani Khoosal, from Microbiology at the NHLS for providing the blood cultures for the 4-month study period and our research nurse, Mrs Mirriam Tshabalala, who assisted with obtaining parental consent.