Comparative analysis of platelet depleted plasma prepared on the Roche 8100 automation line and manually centrifuged platelet poor plasma for routine coagulation assays

Abstract

Objectives: To evaluate whether the routine coagulation tests can be performed using platelet depleted plasma (PDP, residual platelet count <40000/μL) to achieve maximum efficiency of the automated workflow and compare results of these tests performed with platelet poor plasma (PPP residual platelet count <10,000/μL) prepared manually 'offline'.

Design and methods: The PDP was obtained first following 'on line' centrifugation at 4150 RPM (3000g) for 7 min. The routine coagulation tests, Prothrombin Time (PT), Activated Partial Thromboplastin Clotting Time (aPTT), D-dimer (DD), Antithrombin III (AT3) and Fibrinogen (FBG) were performed. The PPP was obtained from an aliquot of PDP samples with additional 'manual off line' centrifugation at 7700 RPM (3314g) for 3 min (total 10 min, online + offline) and the same tests were performed. The statistical analysis was carried out using EP Evaluator v11 to compare results from both methods.

Results: The results from both PPP and PDP samples demonstrated strong correlation. For example, PT (R = 0.9989; N = 55, and of Bias -0.12 (-0.67%), aPTT(R = 0.9957; N = 60, Bias 0.26 (0.58%)), AT3(R = 0.9800; N = 49, Bias -2.0 (-2.2%)), FBG (R = 0.9956; N = 57, Bias -1.9 (-0.5%)) and DD (R = 0.9981; N = 38, Bias 0.005 (0.373%)) with insignificant bias.

Conclusions: The utilization of the Roche cobas® 8100 automated 'online' centrifugation helps achieve optimal workflow efficiency without impacting analytical performance of the PT, aPTT, DD, AT3 and FBG assays. The use of PDP can be superior method to PPP for routine coagulation tests.

Keywords: Activated Partial Thromboplastin Clotting Time; Antithrombin; Coagulation; D-Dimer; Fibrinogen; Hematology; Laboratory automation; Pre-analytical automation; Prothrombin Time.

Fig. 1

Method comparison of PT between the new method using PDP (automated centrifugation) and the existing reference method using PPP (manual centrifugation). Deming regression analysis shows excellent correlation between the new method and reference method, both the methods generate almost identical PT results: y (new method) = 0.995 x (reference method) + (−0.03), R = 0.9990, N = 55.

Fig. 2

The aPTT results between the new method using PDP (automated centrifugation) and the existing reference method using PPP (manual centrifugation). Deming regression analysis shows excellent correlation between the new method and reference method, both the methods obtain almost identical aPTT results: y (new method) = 1.007 x (reference method) + (−0.08), R = 0.9957, N = 60.

Fig. 3

The comparison of DD results between the new method using PDP (automated centrifugation) and the existing reference method using PPP (manual centrifugation). Deming regression analysis shows excellent correlation between the new method and reference method, both the methods obtain almost identical DD results: y (new method) = 0.997 x (reference method) + 0.009), R = 0.9981, N = 38.

Fig. 4

Method comparison of AT3 results between the new method using PDP (automated centrifugation) and the existing reference method using PPP (manual centrifugation). Deming regression analysis shows excellent correlation between the new method and reference method, both the methods obtain almost identical AT3 results: y (new method) = 1.012 x (reference method) + (−3.1), R = 0.98, N = 49.

Fig. 5

Method comparison of FBG results between the new method using PDP (automated centrifugation) and the existing reference method using PPP (manual centrifugation). Deming regression analysis shows excellent correlation between the new method and reference method, both the methods obtain almost identical FBG results: y (new method) = 0.979 x (reference method) + 6.0, R = 0.9956, N = 57.