Abstract Number: OC 44.2
Meeting: ISTH 2021 Congress
Background: Patients with lupus anticoagulant (LA) are at risk for thromboembolic events. However, LA results may vary or become negative over time. The extent and clinical implications of this variability remain uncertain.
Aims: Evaluate variability of LA in LA positive patients with or without history of thrombosis and explore predictors of LA status and its association with future thrombotic events.
Methods: Patients with at least 2 previous positive LA-tests were serially monitored for LA, antiphospholipid antibodies (aPLAs), and thrombotic events within the prospective Vienna Lupus Anticoagulant and Thrombosis Study (LATS).
Results: One-hundred-sixty-four patients were enrolled (Table 1). During a median follow-up of 10.1 years and 1,438 follow-up visits (median visit/patient=9), 43 (26%) patients became LA negative at least once, cumulative 10-year incidence of at least one negative LA test of 26% (95%CI: 19.34, Figure 1). 28/43 (65%) patients turned LA positive again. The strongest predictor for a negative LA test was VKA use (Subdistribution hazard ratio (SHR)=3.13, 95%CI: 1.88-5.22). After adjusting for VKA, baseline PTT-LA independently predicted a lower risk of becoming LA negative (VKA-adjusted SHR/10sec increase in aPTT-LA=0.90, 95%CI: 0.82-0.99). Fifty thrombotic events (arterial n=23, venous n=27) were observed and 24 patients died, corresponding to 10-year prospective ATE, VTE and overall thrombosis incidences of 14% (95%CI: 9-21), 20% (13-28), and 34% (26-43), and 10-year mortality of 14% (9-22), respectively. In multi-state time-to-event analysis, developing a negative LA test was not associated with subsequent ATE risk, VTE risk, total thrombosis risk, nor mortality.
Table 1. Baseline characteristics of the study population – Distribution overall and by LA negativity event status (n=164) | ||||
---|---|---|---|---|
Variable at study enrollment | Overall (n=164) |
LA positive throughout F/U (n=121) |
≥1 negative LA test during F/U (n=43) |
p |
Age at entry (years) | 42 [31-58] | 42 [31-60] | 38 [31-54] | 0.361 |
Female Gender | 137 (84%) | 103 (85%) | 34 (79%) | 0.358 |
Prior history of thrombosis | 98 (60%) | 64 (53%) | 34 (79%) | 0.003 |
Established APS | 118 (72%) | 81 (67%) | 37 (86%) | 0.017 |
SLE and/or LLD | 45 (27%) | 30 (25%) | 15 (35%) | 0.203 |
VKA at baseline | 49 (30%) | 29 (24%) | 20 (47%) | 0.006 |
Lupus-sensitive aPTT (sec) | 87 [69-116] | 88 [73-117] | 79 [65-115] | 0.210 |
“Triple positivity”* | 64 (42%) | 42 (38%) | 22 (54%) | 0.080 |
Reported data are medians [25th-75thpercentile] for continuous data, and absolute frequencies (%) for count data. Abbreviations: LA – Lupus anticoagulant, F/U – follow-up, p – p-values from rank-sum tests and χ2-tests (as appropriate), APS – Antiphospholipid syndrome, SLE – Systemic lupus erythematosus, LLD – Lupus-like disease, aPTT – activated partial thromboplastin time, VKA – vitamin K antagonist *Cutoffs for triple positivitywere defined as follows: anticardiolipin antibody >40 GPL/MPL U/mL; aβ2-glycoprotein IgG >8 GPL/MPL U/mL, and patient had to be positive in at least one antibody isotype (i.e. positive IgM aCL combined with positive IgG aß2-GPI did not fulfill criteria for triple positivity). |
Conclusions: Approximately 25% of patients with LA experienced at least one negative LA test over 10 years. VKA was the strongest determinant of this variation. Developing a negative test neither predicted decreased nor increased thrombosis risk. Thus, variation in LA test positivity has limited utility towards personalized thrombosis risk stratification in this setting.
To cite this abstract in AMA style:
Colling M, Posch F, Koder S, Ay C, Pabinger I, Gebhart J. Predictors of Lupus Anticoagulant Test Variability over Time and its Associations with Future Thrombotic Events: Results from the Vienna Lupus Anticoagulant and Thrombosis Study (LATS) [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/predictors-of-lupus-anticoagulant-test-variability-over-time-and-its-associations-with-future-thrombotic-events-results-from-the-vienna-lupus-anticoagulant-and-thrombosis-study-lats/. Accessed May 18, 2024.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/predictors-of-lupus-anticoagulant-test-variability-over-time-and-its-associations-with-future-thrombotic-events-results-from-the-vienna-lupus-anticoagulant-and-thrombosis-study-lats/