Evaluation of PA990pro, an Analyzer for C-Reactive Protein Using Whole Blood: Hematocrit Correction is Required

The rapid detection of C-reactive protein (CRP) in whole blood can provide a basis for reducing the use of antibiotics, especially for infants in whom blood collection is difficult. Whether the performance of PA990pro for CRP detection can meet clinical needs has not been studied.

Between May and June 2022, 230 blood samples were collected to explore the analytical performance of the PA990pro for CRP detection. The blank check, carryover, repeatability, intermediate precision, linearity, sample stability, the influence of hematocrit (HCT)/triglyceride/bilirubin, and the trueness of the PA990pro were evaluated. Whole blood CRP test results analyzed using the PA990pro were compared to plasma CRP test results from a Hitachi 7180 biochemical analyzer, using the same samples.

The blank check (≤ 0.3 mg/L), carryovers (≤ 0.05%), repeatability (≤ 7.23%), and intermediate precision (≤ 7.36%) can meet clinical needs. The linear correlation coefficients of different ranges of CRP were good (r >0.975), and the slopes were all within 0.950 - 1.050. The stability of samples was good within 72 hours whether stored at 18 - 25℃ or 2 - 8℃ (CV < 10%). With interference from triglycerides at ≤ 7 mmol/L, the deviation of CRP was < 10% and with bilirubin at ≤ 216 μmol/L, the deviation of CRP was < 10%. PA990pro has no HCT quantification function; abnormal HCT will significantly interfere with whole blood CRP results (the relative deviation in the basic experiment was up to 73.71%). We suggest that the HCT results of the patient during the same period are provided through the laboratory information system (LIS) so that a CRP correction formula (CRPcorrected = CRPmeasured*(1 - 40%)/(1 - HCTmeasured)) can be used on the LIS. After using the formula to perform the HCT correction, the results of PA990pro were well correlated with the 7180 analyzer plasma CRP detection (r > 0.975). PA990pro could pass the external quality assessment of the National Center for Clinical Laboratories.

The CRP detection performance of PA990pro can meet clinical needs, but it is suggested that HCT should be corrected by the formula set in LIS. It is a simple, rapid, and cost-free approach that can be used to obtain a modified whole blood CRP test result that meets clinical needs.