[Performance verification and clinical application evaluation of D-dimer assay]

Objective: To evaluate the clinical application performance of a domestic D-dimer assay reagent (ADX D-dimer). Methods: A total of 546 residual sodium citrate anticoagulated plasma samples (530 of which were used for comparability validation and 16 for sample preparation of other validation components) were selected after the completion of clinical testing at Peking Union Medical College Hospital from Jun 2022 to May 2023. According to the American Clinical Laboratory Standards Institute (CLSI) guidelines, national health industry standards and relevant references, the performance of ADX D-dimer used in Sysmex CS 5100 fully automated coagulation analyzer which included accuracy, precision, linear range, carryover rate, interference resistance capability and reference interval were validated and the agreement compared with two mainstream imported detection reagents (reagent A: Vidas D-dimer reagent; reagent B: Innovance D-dimer detection reagent) was evaluated. The clinical diagnostic efficacy of the ADX D-dimer was evaluated using the ELISA D-dimer (reagent A) test results as criteria. Results: The linear correlation coefficient of the 6-point calibrated absorbance and target value was 0.998, the bias of accuracy met the requirements (-2.8%-8.4%), and the coefficient of variation (CV) of within-run and between-day precision of the two levels were 1.0%-2.7% and 2.7%-4.1%, respectively, which were less than the requirements of the manufacturer's statement and the national health industry standard. The linear range within 0.33-9.69 mg/L FEU was verified and the carryover rate was 0. There was no significant interference with the assay results at bilirubin F≤0.22 g/L, bilirubin C≤0.22 g/L, hemoglobin≤5.5 g/L and celiac≤2 800 FTU. The manufacturer's reference interval≤0.5 mg/L FEU was verified suitable for this laboratory. For 358 samples without suspicious heterophilic antibody whose D-dimer levels range from 0.06 to143.63 mg/L FEU, the correlation between ADX D-dimer and another two assay was good, with r values being 0.968 and 0.975, respectively, the percentage of deviation and relative deviation beyond the 95% confidence interval was 3.4%-4.5% and 5.3%-7.0%. The correlation between ADX D-dimer and ELISA D-dimer was better than that of reagent B in the concentration range of 0.06-1.00 mg/L FEU (r=0.858, 0.134). For 172 samples with heterophilic antibody, the correlation between ADX D-dimer and ELISA D-dimer was still good(r=0.827), with the percentage of deviation and relative deviation being 6.4% (11/172). The diagnostic efficacy was evaluated using 530 samples, and the sensitivity, specificity, positive predictive value, negative predictive value of ADX D-dimer was 97.4%, 77.6%, 91.9%, 91.9%. The area under the curve was 0.976 (95%CI: 0.964-0.987, P<0.001). Conclusion: The ADX D-dimer reagent has superior assay and diagnostic performance, and can meet the needs of clinical laboratories.