AB0369 CORRELATION OF THE FIRST LATERAL FLOW-BASED POINT OF CARE TEST TO QUANTIFY INFLIXIMAB AND ANTI-INFLIXIMAB ANTIBODIES IN A FINGER PRICK SAMPLE WITH THE REFERENCE ELISA TECHNIQUE

Abstract

BackgroundCurrent techniques to monitor clinical response may require several days and centralised facilities, which may cause delays in effective therapeutic decisions. Therefore, the use of a rapid decentralized test will facilitate patient management and improve patient care.ObjectivesThe goal of this study was to validate the use of capillary blood in a real point-of-care (POC) setting for rheumatic patients under infliximab treatment by using Promonitor Quick lateral flow (LF) tests. Results were compared to the Promonitor ELISA reference technique in serum samples used by centralised laboratories.MethodsA prospective, observational study was designed to evaluate the performance of a rapid LF test (Promonitor Quick IFX, Progenika, Spain). 160 infliximab treated rheumatology consecutive patients (400 samples) were recruited in two hospitals in Galicia, Spain. Prior to the infusion, a finger prick sample was obtained and analysed. Anti-infliximab antibodies were also determined with Promonitor Quick ANTI-IFX1-4. Results were read with the automated portable PQreader instrument. Additionally, a serum sample was collected for subsequent comparative analysis with either LF or ELISA tests.Qualitative (positive (PPA) and negative (NPA) agreements) and quantitative (Pearson correlation and bias) performance of the LF test was compared to ELISA, as well as between different specimens following CLSI EP09-A3.ResultsOverall agreement between Promonitor Quick IFX finger prick and ELISA test was 91% (88% PPA; 100% NPA). The quantitative comparison showed a good correlation (Pearson correlation coefficient: 0.85 and observed bias: 25%) (Table 1).Table 1.Performance results: infliximab drugQualitative ComparisonN*PPANPAoverallPOC finger prick vs ELISA27488%100%91%POC serum vs ELISA28198%100%98%Quantitative ComparisonN*Pearson correlationBiasPOC finger prick vs ELISA1650.8525%POC serum vs ELISA1810.916%*Only samples in the common measurement range for both methods considered.Performance results: anti-infliximab anti-drug antibodiesQualitative ComparisonN*PPANPAoverallPOC finger prick visual vs. PQreader396100%99%99%POC serum visual vs PQreader398100%100%100%POC finger prick PQreader vs ELISA39390%99%98%POC serum PQreader vs ELISA39589%100%99%Similar results were also observed when serum was used with either the LF or the ELISA tests (98% overall agreement, 0.91 correlation coefficient; 6% bias) (Table 1).Overall agreements for visual and automated (PQreader) interpretations with Promonitor Quick ANTI-IFX were 99% and 100% for finger prick and serum specimens, respectively (Table 1).ConclusionPromonitor Quick can be used to reliably quantify infliximab in capillary blood samples and results are comparable to those obtained with the reference ELISA technique. The use of the rapid POC test with finger prick will allow clinicians to monitor their patients in a fully decentralized mode to aid in the decision making process. PQreader is a sensitive portable equipment to report drug as well as antibody levels in the patient samples.