Correlation between activated partial thromboplastin time and anti‐Xa activity in patients who received low‐molecular weight heparin as anticoagulation for haemodialysis

Abstract

Plasma anti-Xa activity, the recommended test to monitor low-molecular weight heparin (LMWH) therapy, is not readily available in many laboratories. In our clinical trials on the use of LMWH as anticoagulation for haemodialysis, a consistent prolongation of APTT in addition to the elevated anti-Xa activity was observed in the patients after LMWH administration. Hence, the paired anti-Xa activity and APTT data were re-analyzed. The APTT ratio, which was the proportional change in APTT from the baseline value after LMWH administration, was found to have a strong correlation with anti-Xa activity (coefficient of determination, R = 0.72, P< 0.001). In the receiver operating characteristic analysis, the APTT ratio was also found to be an excellent predictor of therapeutic anti-Xa activity ≧0.5 IU/mL (area under curve = 0.93, P < 0.001). The sensitivity was 88% and the specificity was 83.3% when an APTT ratio ≧1.4 was used as the cut point to predict the achievement of therapeutic anti-Xa activity. Our results illustrated that APTT is a potentially useful screening test to assess the degree of anticoagulation achieved by LMWH during haemodialysis, if the testing for plasma anti-Xa activity is not available.

Expanded hemodialysis: Is anticoagulation of the dialysis circuit different from online hemodiafiltration and high‐flux hemodialysis?

“…Although the end‐dialysis target for aXa has not been clearly established, some reports have suggested a target of >0.4 IU/mL [12,15,16,27]. In our study, however, the end‐dialysis target for aXa was, in all cases, in accordance with that of other authors, who recommended aXa < 0.4 IU/mL [17,18], which is lower than the recommendations for aXa in the initial treatment of thrombosis (0.4–0.6 IU/mL) [27,28] and similar to the target for patients with an elevated risk of bleeding (i.e., 0.2–0.4 IU/mL) [2,29,30]. Thus, our study points out that using the venous port with low doses of enoxaparin is safe; however, patients at high‐risk of bleeding were excluded, and only one session in each arm of treatment was conducted; therefore, more studies are needed in this regard.…”