Outcomes in children with provoked venous thrombosis and antiphospholipid antibodies: findings from the Kids-DOTT trial.

Few studies have prospectively evaluated the incidence and outcomes in children with provoked venous thromboembolism (VTE) and transient or persistent antiphospholipid antibodies (aPLs). We compared outcomes of patients aged <21 years with a first-episode acute provoked VTE and positive aPL at diagnosis, enrolled in the Multicenter Evaluation of the Duration of Therapy for Thrombosis in Children trial. aPLs were tested at enrollment and, when positive, repeated at 6 weeks after VTE diagnosis. Subsequent testing was performed at the discretion of the treating hematologist. Of 524 patients, 116 (22%) had positive aPLs at enrollment. At follow-up, 70 (60%) had transient (n = 66) or low-titer aPLs (n = 4), 11 (10%) had persistent aPLs meeting the criteria for antiphospholipid antibody syndrome (APS), and 35 (30%) had no repeat testing. Patients with APS were older (15.8 vs 9.9 years; P = .014) and had a statistically significant higher risk of symptomatic recurrent VTE (18% vs 1%; odds ratio [OR], 12.2; 95% confidence interval [CI], 1.4-108; P = .025) and a statistically nonsignificant but clinically meaningful difference in the risk of anticoagulant-related clinically relevant bleeding (9% vs 0%; OR, 20.1; 95% CI, 0.7-558; P = .077) compared with those in the transient or low-titer aPL group. In conclusion, aPLs are common in young patients with acute provoked VTE and are mostly transitory and clinically insignificant. Patients with APS and provoked VTE appear to have an increased risk of recurrent VTE compared with patients with transitory or low-titer aPLs. Future collaborative studies should investigate the optimal VTE management for children with provoked VTE who meet the criteria for APS. The trial was registered at www.ClinicalTrials.gov as #NCT00687882.