Antiphospholipid antibodies in pediatric systemic lupus erythematosus

Antiphospholipid antibodies (aPLs) have been extensively studied in adults with systemic lupus erythematosus (SLE) and have been associated with arterial and venous thrombosis, thrombocytopenia, neurologic disorders, and recurrent fetal loss. In contrast, very little is known about the frequency and clinical significance of aPLs in pediatric SLE. This study was designed to determine the frequency of aPLs in pediatric SLE and the temporally associated clinical manifestations.

We studied 29 consecutive patients with onset of SLE in childhood seen in the Pediatric Rheumatology Clinic at the University of Pittsburgh, Children's Hospital, between 1985 and 1992. We defined aPL as the presence of a lupus anticoagulant (LAC), immunoglobulin G or immunoglobulin M anticardiolipin antibodies (aCLs), or a biologic false-positive serologic test for syphilis determined by a VDRL test. Clinical manifestations were temporally correlated to the presence of aPLs if they occurred within 6 months.

Overall, 19 (65%) of 29 children with SLE had one of the three laboratory abnormalities defining aPL. LAC was detected in 16 (62%) of 26, aCL in 18 (66%) of 27, and false-positive VDRL test results in 11 (39%) of 28. Twenty-five of the 29 patients had all three tests performed. In 10 patients, all three tests were abnormal. The presence of thrombosis in 7 patients (4 venous, 2 arterial, and 1 both) was associated with a positive aPL, specifically aCL. The presence of an aPL was significantly associated with anti-double-stranded DNA antibodies, but not with neuropsychiatric manifestations or with thrombocytopenia. The presence of an aCL was significantly associated with hemolytic anemia. A prolonged prothrombin time, in the setting of an LAC (all with a prolonged activated partial thromboplastin time), was associated with life-threatening disease in 6 of 15 patients.

Sixty-five percent of 29 consecutive pediatric patients with SLE had evidence of aPL. The presence of aPL, specifically aCL, was significantly associated with thrombotic events. The presence of a prolonged prothrombin time in the setting of an LAC may be a marker of more serious disease in pediatric SLE.