Mda 180 coagulometer

At the 20‐year examination, blood was anticoagulated with K₂ EDTA (1.5 mg/ml) for measurement of full blood count (Coulter S), and plasma viscosity at 37°C in a semi‐automated capillary viscometer (Coulter Electronics). Blood was also anticoagulated with 0.109 M trisodium citrate (9:1 v:v) for measurement of clottable fibrinogen (Clauss method); as well as coagulation factors VII, VIII and IX; activated partial thromboplastin time (APTT) and activated protein C (APC) ratio (as a measure of APC resistance) in an MDA‐180 coagulometer (Organon Teknika). Fibrin D‐dimer was measured with an enzyme‐linked immunosorbent assay (Biopool AB) as was von Willebrand factor (VWF) antigen (Dako). C‐reactive protein (CRP) was assayed by ultra‐sensitive nephelometry (Dade Behring). Interleukin‐6 (IL‐6) was assayed using a high‐sensitivity ELISA (R & D Systems). Distributions and laboratory coefficients of variation have been described previously.¹²

At the 20-year examination, blood was anticoagulated with 0.109 M trisodium citrate (9:1 v:v) for measurement of clottable fibrinogen (Clauss method); as well as coagulation factors VII, VIII and IX; activated partial thromboplastin time (APTT) and activated protein C (APC) ratio (measured by the aPTT-based method) in an MDA-180 coagulometer (Organon Teknika, Cambridge, UK). Plasma levels of D-dimer were measured with enzyme-linked immunosorbent assays (Biopool AB, Umea, Sweden) as was von Willebrand factor (VWF) antigen (DAKO, High Wycombe, UK). C-reactive protein was assayed by ultra-sensitive nephelometry (Dade Behring, Milton Keynes, UK). Distributions and laboratory coefficients of variation have been described previously [9] .

Plasma from fasting venous blood samples taken at baseline was frozen for storage. Plasma NT-proBNP and hs-cTNT were subsequently measured using the Elecsys 2010 electrochemiluminescence method (Roche Diagnostics, Burgess Hill, UK), and calibrated using the manufacturer's reagents. The manufacturer's controls were used with limits of acceptability defined by the manufacturer. GGT was analysed using a Vitros Fusion chemistry system (Ortho Clinical Diagnostics, High Wycombe, UK) at the Western General Hospital, Edinburgh, UK. Assays for plasma TNF-α, IL-6, CRP and fibrinogen were carried out in the University Department of Medicine, Glasgow Royal Infirmary. TNF-α and IL-6 antigen levels were determined using high-sensitivity ELISA kits (R&D Systems, Oxon, UK). CRP was assayed using a high-sensitivity immunonephelometric assay. Fibrinogen assays were performed using stored plasma anticoagulated with trisodium citrate and the automated Clauss assay (MDA-180 coagulometer, Organon Teknika). ABI was measured as described previously as the ratio of systolic BP in the ankle to that in the arm [14] (link). Participants with a value > 1.4 (n = 17), indicative of medial arterial calcinosis rather than atherosclerosis, were subsequently omitted, in line with previous studies [29] .