Significance of Lupus Anticoagulant in Children with Prolonged Prothrombin Time/activated Partial Thromboplastin Time

Jo, Jeong Hyun; Son, Dong Woo; Jeon, In Sang

Abstract

BACKGROUND
The prolongation of prothrombin time (PT)/activated partial thromboplastin time (aPTT) in vitro occurs from various causes and lupus anticoagulant (LA) is one of them. This study was performed to investigate the association between prolonged PT/aPTT and LA in children.
METHODS
This study included 66 subjects, who showed prolonged PT/aPTT on routine examination and screening test prior to an invasive procedure. LA was investigated in subjects with only PT prolongation, only aPTT prolongation, and PT/aPTT prolongation. The aPTT prolongation subjects were subdivided into more prolonged (â‰¥60 sec) and less prolonged (39.6â‰¤aPTT<60 sec). In addition, the sensitivity and specificity of LA in PT or aPTT prolongation was evaluated by ROC (receiver operating characteristics) curve.
RESULTS
The frequency of LA positivity was 60.6% in PT or aPTT prolongation subjects. The frequency and titer of LA were higher in the order of prolonged PT group, prolonged aPTT group, and prolonged PT/aPTT (P<0.01). The frequency and titer of LA were higher in more prolonged aPTT group than less prolonged group (P<0.01). The accuracy of sensitivity and specificity of LA in cases with PT prolongation was low (area under the ROC curve was 0.68), however, was high (0.89) in cases with aPTT prolongation. The sensitivity and specificity of LA in predicting aPTT prolongation time of more than 42.9 sec were 0.83 and 1.00, respectively.
CONCLUSION
PT was less affected than aPTT by LA and aPTT prolongation could more accurately predict LA existence. A large portion of PT or aPTT prolongation found in children without obvious past or family history of bleeding, especially accompanying infectious disease, might be associated with LA.