A shortened APTT coexisting with a low APC resistance ratio was associated with a significantly higher incidence of venous thromboembolism compared to normal APC resistance (36% vs 7%, P=0.003).
Cohort (n=69)
Does a low APC resistance ratio increase the incidence of VTE in hospital patients with shortened APTT?
A shortened APTT coexisting with a low APC resistance ratio is a marker for increased risk of venous thromboembolism, regardless of Factor V Leiden carriership status.
Absolute Event Rate: 36% vs 7%
p-value: p=0.003
A cohort of 69 hospital patients with shortened activated partial thromboplastin time (APTT) were prospectively identified and were further investigated for resistance to activated protein C (APC). This was quantified by APTT-based and Russel viper venom time (RVVT)-based methods. The prevalence of objectively confirmed venous thromboembolism (VTE) in this cohort was 19% (13/69). Of these 69 patients, 28 also had low APC resistance ratios and the incidence of VTE among these patients (group 1) was 36% (10/28). This was significantly higher (P=0.003) than that in the remaining 41 patients (group 2) with shortened APTT and normal APC resistance (7%, 3/41). DNA analysis confirmed 13 of the group 1 patients were FV Leiden positive. The incidence of VTE in the FV Leiden group (group 1a, n=13) was 38% (5/13) and in the group whose abnormal resistance to APC was independent of FV Leiden (group 1b, n=15) was 33% (5/15). These results suggest that a shortened APTT, coexisting with a low APC resistance ratio, regardless of FV Leiden carriership status, is a marker for VTE. Increased resistance to the anticoagulant activity of APC is multifactorial as reflected by evidence of abnormal resistance differing in the two assays.
ABOUD et al. (Sun,) conducted a cohort in Shortened activated partial thromboplastin time (APTT) (n=69). Low APC resistance ratio vs. Normal APC resistance ratio was evaluated on Venous thromboembolism (VTE) (p=0.003). A shortened APTT coexisting with a low APC resistance ratio was associated with a significantly higher incidence of venous thromboembolism compared to normal APC resistance (36% vs 7%, P=0.003).