Work

Normalization of activated partial thromboplastin time and diluted Russell’s viper venom time ratios can be safely omitted in the assessment of lupus anticoagulant

Year: 2026

Type: article

Abstract: Background: Normalization of lupus anticoagulant (LA) ratios is recommended by both the Clinical & Laboratory Standards Institute and the International Society of Thrombosis and Hemostasis to reduce inter-assay and intra-assay variation. This study evaluates if the normalization step can be safely omitted. Methods: = 306). Clinical classification (positive/negative) in the first dataset served as the reference standard, enabling the establishment of optimal cut-off values for the non-normalized LA ratios using receiver operating characteristic calculations and Youden's J statistic with bootstrapping. These optimal non-normalized cutoffs were then used on the validation set to compare the number of reclassifications when compared with normalized LA ratios. Results: Receiver operating characteristic analysis demonstrated high discriminative performance of non-normalized LA ratios for both dilute Russell's viper venom time (area under the curve 0.9818; 95% CI, 0.9462-1) and activated partial thromboplastin time (area under the curve 0.8926; 95% CI, 0.8077-0.9775). Youden's J identified optimal cut-off values of 1.304 for dilute Russell's viper venom time (95% CI, 1.297-1.307) and of 1.554 for activated partial thromboplastin time (95% CI, 1.504-1.562). Applying the above criteria to the validation dataset resulted in no reclassifications. Conclusion: The normalization step in the analysis of LA ratios can be safely omitted, allowing for a reduced laboratory workload, without affecting result interpretation and thus clinical outcomes.

Source: Research and Practice in Thrombosis and Haemostasis

DOI: 10.1016/j.rpth.2026.103376

Authors: Adrian Kimiaei, Jovan Antovic, Charlotte Gran

Institutions: Karolinska University Hospital, Karolinska Institutet

Language: English

Topic: Systemic Lupus Erythematosus Research

Subfield: Rheumatology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,250