Analytical evaluation of the Radiometer AQT90 FLEX βhCG assay

Abstract

ObjectivesMany hospitals cannot afford an hCG assay on a central lab analyzer and turn to point of care testing (POCT) solutions. The Radiometer AQT90 FLEX is a small benchtop immunoareement between the AQT90 and comparator methods for samples with hCG ssay analyzer for use in the laboratory or at the patient bedside. This study evaluated the analytical performance of the AQT90's βhCG assay.MethodsPrecision was assessed using whole blood patient samples and two levels of quality control. Linearity was assessed by dilution of a high hCG plasma sample. Carryover and hook effect were assessed using high and low hCG samples. Method comparisons were done against Abbott i-STAT Total βhCG, Beckman Coulter Total βhCG (5th IS), and Roche hCG+β. Sample concentrations ranged from<2 IU/L to 4,973 IU/L.ResultsRepeatability and within-laboratory precision passed most manufacturer's claims and allowable error criteria. Linearity was validated from<2 IU/L to 4,741 IU/L. Hook effect was not observed up to 2,446,448 IU/L. Carryover was<4.0 ppm. A linear relationship was observed with i-STAT, Beckman and Roche methods. At>20 IU/L, biases were apparent against all three comparator assays (i-STAT: +20%, Roche: +30%, Beckman: +5 to 15%). At ≤20 IU/L, the acceptability of agreement varied according to TAE specifications. Concordance between AQT90 and comparator assays using 5 IU/L as the medical decision level ranged from 69% to 81%.ConclusionsOverall, the AQT90 hCG assay performed well and would be suitable for smaller suburban or rural hospitals. Some limitations have been noted and should be kept in mind during clinical testing.

Optimization of Patient Management in the Gynecology Emergency Department Using Point-of-Care Beta hCG

“…One sample with an βhCG value > 1,000,000 IU/L gave the similar result of >5000 IU/L on AQT 90. Our results, in accordance with those previously obtained [ 15 ], confirm the manufacturer’s claim of no hook when βhCG concentrations up to 233,000 IU/L are measured.…”

“…The performances and diagnostic accuracy of the assay were found to be clinically acceptable. The within-lab imprecision was less than 4% and comparable to previously reported CVs of 3.5-3.9% and 2.8-5.1% for level 1 and level 2 QC material, respectively [15]. The present study confirmed a positive bias evaluated at 10% compared to the Roche Elecsys hCG + β method on a e602/cobas 8000 analyzer [15].…”

“…The only discordant result pair was a βhCG < 2 IU/L using the Roche Elecsys βhCG and was equal to 2 IU/L using the AQT βhCG. The agreement of the AQT90 with the Roche assay using 5 IU/L, corresponding to the level of the medical decision generally used to exclude a diagnosis of pregnancy in premenopausal women [ 26 , 27 ], was 99%, much better than that previously reported at 75% [ 15 ]. βhCG qualitative tests on POC devices are susceptible to false negative results because of a lower limit of detection of 10 to 25 IU/L [ 12 , 13 , 14 ].…”

“…To the best of our knowledge, no study has addressed the impact of quantitative hCG measurement in gynecology EDs. Three POCT quantitative hCG assays performed in whole blood are commercially available in France: the Radiometer AQT90 FLEX βhCG test kit [ 15 ], the Siemens Stratus CS Acute Care βHCG assay [ 16 ] and the Abbott i-STAT Total βhCG) assay [ 17 ]. These POCTs provide βhCG results in 10 to 18 min [ 15 , 16 , 17 ].…”

Quantitative Point of Care testing of HCG in early pregnancy units: A Review

“…Ortho Vitros 3600/5600/ECi 0.998 14 The Radiometer AQT90 method is based on an all in one dry chemistry concept, CE certified using whole blood samples, with a volume 0.3 -2ml, with a total assay time of 18 minutes and a working range of 1 -5,000 IU/L. The agreement or concordance of the Radiometer AQT90 was 69% with the Abbott i-STAT, 81% with the Beckman Coulter and 75% with the Roche methods [15].…”