Abstract:Objective To investigate the sensitivity differences betwen STA-PTTA and Actin FSL reagents in lupus anticoagulant (LA) screening in children, and to preliminarily evaluate the potential adjunctive value of clot waveform analysis (CWA) using Actin FSL reagent. Methods A total of 11O plasma samples from children confirmed as LA-positive cases by dilute russell viper venom time (dRVVT),including 43 weakly positive and 67 positive cases,were consecutively enrolled,together with 111 healthy pediatric controls. Activated partial thromboplastin time（APTT)was measured using the STA-R Evolution coagulation analyzer(with STA-PTTA reagent) and the Sysmex CN-6ooo coagulation analyzer （with Actin FSL reagent). The differences in positivity rates under various criteria and APTT ratios between the two reagents were compared. A preliminary analysis of CWA parameters was conducted. Results When using age-specific APTT reference interval as the criterion, the sensitivity of both reagents was 92.7% (102/110).When the criterionwassetasAPTTprolongationexceeding theupper limit of thereference interval by>5seconds,the sensitivity of STA-PTTA was significantly higher than that of Actin FSL(90.0%vs.70.0%,P