Comparison of different algorithms for lupus anticoagulant detection: a single-center experience

Background: The laboratory tests for lupus anticoagulant (LA) detection comprise complex and multistep coagulation testing procedures. There is no established gold standard assay or direct comparison of algorithms as recommended by different guidelines. Objectives: This study aimed to evaluate and compare the LA detection performance of different laboratory algorithms suggested by the existing guidelines. Methods: The routine LA test data of 1801 plasma samples, including 188 LA-positive and 1613 LA-negative samples, were re-evaluated by applying the algorithms recommended by existing guidelines and were interpreted using various methods. Diagnostic performance indices for each LA detection algorithm were compared with those of the other algorithms. The efficacies of the different interpretation methods were analyzed to determine a suitable interpretation methodology for each assay. Results: The diagnostic performance for detecting LA varied by the algorithm and method of interpretation used. All laboratory algorithms displayed exceptional diagnostic performance with all diagnostic parameters of >90.0%. Nearly perfect agreement was observed in all algorithms when compared to the Clinical and Laboratory Standards Institute 2014 guideline interpreted by normalized screen-to-confirm ratio (NSCR) and mixing test-specific cutoff (MTC), as a reference assay (Cohen's kappa coefficient, >0.90 [range, 0.94-1.00]). A combination of the index of circulating anticoagulant and NSCR was optimal for interpreting the activated partial thromboplastin time-based test, whereas a combination of the MTC and NSCR was suitable for the diluted Russell's viper venom time-based test. Conclusion: All laboratory algorithms showed equivalent diagnostic performance. Establishing the best method of interpretation for each assay is recommended to improve LA detection performance.