PB0412 - Laboratory detection of Lupus Anticoagulant using Dilute Russell's Viper Venom test (DRVVT) and/or Activated Partial Thromboplastin time (APTT): Does it matter?

Sunday, July 10, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Tulasi Geevar, MBBS, MD

Associate Professor
Christian Medical College and Hospital Vellore
Vellore, Tamil Nadu, India

Co-Author(s)

Rutvi Gautam Dave, MBBS, MD, Post-Doctoral Fellow

Associate Professor
Christian Medical College and Hospital Vellore
Vellore, Tamil Nadu, India
PE

Patricia Elizabeth

Senior Technician
Christian Medical College
Vellore, Tamil Nadu, India
AS

Ashok Samuel

Laboratory technician
Christian Medical College, Vellore
Vellore, Tamil Nadu, India
JT

Joel Thamburaj

Technician
Christian Medical College, Vellore
Vellore, Tamil Nadu, India
JM

Joy John Mammen

Professor
Christian Medical College, Vellore
Vellore, Tamil Nadu, India
SN

Sukesh Chandran Nair

Professor
Christian Medical College and Hospital Vellore
Vellore, Tamil Nadu, India

Background: Lupus anticoagulant (LA) is one of the three laboratory criteria for the identification of the antiphospholipid syndrome (APS). Primary criteria for LA detection include prolonged clotting time of a phospholipid dependent test, the failure of correction on mixing study, shortening of the clotting time in the presence of high phospholipid concentrations, and absence of other inhibitors. Dilute Russel Viper Venom Test (DRVVT) is the preferred test, and second test should be a sensitive Activated Partial Thromboplastin time (APTT). LA should be considered positive if one of the two test systems gives a positive result.

Aims: To describe the pattern of LA testing in a tertiary centre in South India and correlate with other antiphospholipid antibodies (APLAs) and clinical features.

Methods: This was a retrospective study wherein all consecutive LA requests from 1st January 2021 to 30th June 2021 were reviewed. LA testing was performed using DRVVT screen and confirm reagents (STA-Staclot DRVV Screen and STA-Staclot DRVV Confirm) and APTT reagent (STA-PTT Automate) using three steps, Screen-mix-confirm. Clinical details and other APLA results were obtained from the electronic medical records.

Results: There were a total of 1471 LA requests during the study period. 41 cases were excluded in view of interferences due to anticoagulants like Heparin, low molecular weight heparin and Dabigatran. A total of 137 LA positive cases were identified, of which 73 were positive by both DRVVT and APTT, 54 positive only by DRVVT and 10 positive only by APTT. There was maximum correlation with other APLAs when LA was positive by both APTT and DRVVT as shown in Figure 1.

Conclusion(s): Positive LA by APTT alone did not show any correlation, while LA positive by both DRVVT and APTT showed maximum correlation with the presence of other APLAs.