Thrombocytopenia predicts thrombosis risk, poor survival in antiphospholipid syndrome
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Persistent low-to-moderate thrombocytopenia can identify patients with antiphospholipid syndrome who are at high risk for thrombosis, and is linked to poor long-term survival, according to data published in Rheumatology.
“Antiphospholipid syndrome (APS) is an autoimmune acquired thrombotic disease that confers long-term an increased mortality respect to general population,” Jose Pardos-Gea, MD, PhD, of the Autonomous University of Barcelona and Vall d'Hebron University Hospital, in Spain, told Healio Rheumatology.
“Up until now, no clear risk factors for mortality have been isolated in APS despite the fact that we have identified subtypes of APS patients with greater thrombotic risk,” he added. “Thrombocytopenia — less than 150x109 platelets/L — is seen in a range of 15% to 50% of APS series and is suspected to be associated with a more thrombotic clinical profile of APS, but its influence on patient survival had never been demonstrated.”
To examine the impact of thrombocytopenia on survival in patients with APS, Pardos-Gea and colleagues conducted a retrospective study of 114 individuals who had been diagnosed and followed at their center from 1980 to 2018. Among these patients, 64% had primary APS, 25% secondary APS and 10% asymptomatic antiphospholipid-antibody (aPL) positivity.
The researchers defined thrombocytopenia as less than 150x109 platelets/L, evaluating it and other predictors among the cohort. They calculated hazard ratios for mortality using Cox-regression models. The mean follow-up was 19 years.
According to the researchers, antinuclear antibodies (HR = 1.8; 95% CI, 0.8-3.6), arterial thrombotic events (HR = 7; 95% CI, 1.4-3.5), myocardial infarction (HR = 8.3; 95% CI, 1.1- 59), intracardiac thrombosis (HR = 17; 95% CI, 1-279) and thrombocytopenia (HR = 2.9; 95% CI, 1.4-6.1) were risk factors for all-cause mortality. However, in the multivariate analysis, only thrombocytopenia (HR = 2.7; 95% CI, 1.3-6) remained significant.
Both persistent (HR = 4.4; 95% CI, 2.1-9.2) and low-to-moderate thrombocytopenia (HR = 2.8; 95% CI, 1.2-6.4) were associated with a significant increase in mortality, compared with acute (HR = 1.6; 95% CI, 0.5-5.3) and severe (HR = 2.1; 95% CI, 0.5-9.2) cases. Patients with APS who demonstrated thrombocytopenia were more frequently male (P=.001), with arterial thrombosis (P=.04), lupus anticoagulant positivity (P=.04), a type I aPL profile (P=.05) and anticoagulant treatment (P=.01). According to the researchers, thrombosis caused 13% of deaths in patients with thrombocytopenia, and 1% in those without (P=.01).
“For the first time in a study focused on APS, a prognostic variable influencing mortality is recognized,” Pardos-Gea said. “We found that persistent low-moderate thrombocytopenia — 50 to 150x109 platelets/L — identifies a subgroup of APS patients at high risk of thrombosis and is associated with a poor long-term survival. Moreover, those patients with thrombocytopenia died more frequently of thrombosis. This finding should derive in clinical studies evaluating the need of different treatment approach for this clinical subtype.”
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