OC 77.3 - Has the time come for anti-PS/PT IgG positivity to replace Lupus anticoagulant testing?

Wednesday, June 26, 2024

10:45 – 11:00 ICT

Room: 211 A-D

Presenting Author(s)

Himil Parikh, MD

Senior resident
All India Institute of Medical Sciences, New Delhi
New delhi, Delhi, India

Co-Author(s)

JD

Jasmita Dass, MD, DM

Associate Professor of Hematopathology
All India Institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
GK

Ganesh Kumar Vishwanathan

Associate Professor
All India Institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
RG

Ranjan Gupta

Associate Professor
All India Institute of Medical Sciences, New Delhi
Delhi, Delhi, India
SA

Shreyam Acharya

Senior Resident
All India Institute of Medical Sciences, New Delhi
Delhi, Delhi, India
MA

Mukul Aggarwal

Assistant Professor
All India Institute of Medical Sciences, New Delhi
Delhi, Delhi, India
PK

Pradeep Kumar

Associate Professor
All India Institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
RC

Richa Chauhan

Assistant Professor
All India Institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
RD

Rishi Dhawan

Associate Professor
All India Institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
NS

Nilanchali Singh

Assistant Professor
All India Institute of Medical Sciences, New Delhi
Delhi, Delhi, India
JB

Juhi Bharti

Associate Professor
All India Institute of Medical Sciences, New Delhi
Delhi, Delhi, India
TS

Tulika Seth

Professor
All India Institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
MM

Manoranjan Mahapatra

Professor and Head
All India institute of Medical Sciences, New Delhi
New Delhi, Delhi, India

Background: Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by persistent anti-phospholipid antibodies (APA), causing vascular thrombosis and obstetric complications. Additional markers like aPS/PT (Anti-Phosphatidylserine/Prothrombin) IgG antibodies have been investigated to improve APS diagnosis and prognosis, addressing discrepancies in existing tests.

Aims: 1) To establish laboratory reference range of aPS/PT IgG antibodies
2) To correlate aPS/PT IgG status with clinical and laboratory criteria of APS

Methods: Total 240 samples were accrued from 193 patients & healthy controls (Figure 1). The study employed a stationary phase Enzyme-Linked Immunosorbent Assay (ELISA) for aPS/PT. DRVVT and APTT based methods were used to identify LA.

Results: Laboratory reference range (RR) for aPS/PT antibodies determined at 36 units. Adhering to manufacturer’s RR, 5 patients would have been mislabelled as aPS/PT positive (titres between 30 to 36). Table 1 shows correlation between aPS/PT with laboratory and clinical profile of patients. Significant concordance of aPS/PT was noted with LA (Cohen’s kappa of 0.91) both on univariate and multivariate analysis while no concordance was seen with B2GP or aCL (Table 1).

aPS/PT also showed a significant correlation with thrombotic profile on both univariate and multivariate analysis (Table 1). Amongst 9 patients where LA could not be tested, 8 had VTE episodes and all tested positive for LA at the second time point, emphasizing importance of LA testing. All these patients were positive for aPS/PT (8 patients positive at first timepoint while all at second timepoint).

Conclusion(s): RR for aPS/PT was slightly higher than the manufacturer’s recommendation and supports development of lab-specific RR. aPS/PT test correlates with LA positivity. Strong association was noted between aPS/PT and LA which emphasizes its use when LA testing is hindered.