Lupus anticoagulant test persistence over time and its associations with future thrombotic events

Data on lupus anticoagulant (LA) test stability in patients persistently positive for LA are limited, and its implications on clinical outcomes are lacking. We investigated the rate and predictors of a negative LA test and whether experiencing a negative test affected a patient's risk of future thrombotic events or death in a prospective observational study of persistently LA(+) patients. We followed 164 patients (84% women) for a median of 9.2 years and a total of 1438 follow-up visits. During the observation period, 50 thrombotic events (23 arterial and 27 venous events) occurred, and 24 patients died. Forty-six of the patients had at least 1 negative LA test during the observation period, corresponding to a 10-year cumulative incidence of a negative LA test of 28% (95% confidence interval, 20-35). The majority of patients with available follow-up after a negative LA test (n = 41) had at least 1 subsequent positive test for LA (n = 28/41, 68%). Vitamin K antagonist (VKA) treatment at baseline was associated with a negative LA test during follow-up. Using a multistate time-to-event model with multivariable adjustment, a negative LA test had no impact on a patient's prospective risk of thrombosis or mortality. We conclude that a negative LA test during observation cannot be used clinically to stratify a patient's risk for future events.

Automated summary

Data on the stability of lupus anticoagulant (LA) test results and their implications on clinical outcomes are limited for persistently positive LA patients. This study followed 164 patients and found a 28% incidence of negative LA tests during the observation period. However, a negative LA test did not predict future thrombotic events or mortality in these patients.