Influence of apixaban on commonly used coagulation assays: results from the Belgian national External Quality Assessment Scheme.

INTRODUCTION: The Belgian national External Quality Assessment Scheme performed a survey to assess the effect of the direct oral anticoagulant apixaban on the coagulation assays prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and antithrombin as performed with a large number of reagent/instrument combinations. METHODS: Four lyophilized plasma samples spiked with apixaban (0, 41, 94 and 225 ng/mL) were sent to the 195 Belgian and Luxembourg clinical laboratories performing coagulation testing. RESULTS: PT and aPTT were barely influenced at the concentrations tested. At 225 ng/mL apixaban, PT and aPTT clotting times were only 1.15 times longer than at 0 ng/mL. Among PT reagents, RecombiPlasTin 2G® showed a slightly higher sensitivity with 225 ng/mL apixaban prolonging the PT clotting time 1.3-fold. Among aPTT reagents, there was no appreciable difference in sensitivity. Fibrinogen results were unaffected by the presence of apixaban, but antithrombin activity was considerably overestimated when measured with a FXa-based assay. At 225 ng/mL apixaban, the median percentage increase in antithrombin level was 31% when measured with the Liquid Antithrombin® reagent and 44% with the Innovance Antithrombin® reagent. CONCLUSION: Our data provide clinical laboratories with useful information on the impact of apixaban on their routine coagulation assays.

The order of draw: much ado about nothing?

INTRODUCTION: The 'order of draw' has been advocated since 1982 to reduce the risk of cross-contaminating blood tubes with additives from a previously filled tube. METHODS: We studied 193 patients receiving oral anticoagulation. Multiple tubes were collected in a specific order using the Sarstedt Safety Monovette System. We evaluated the effect of the 'order of draw' on the prothrombin time/international normalized ratio (PT/INR) and the activated partial thromboplastin time (APTT) when the citrate tube is drawn as the first tube, second tube or after a heparin, EDTA or serum tube with clot activator. RESULTS: There was no statistically significant influence on the PT/INR. The same applies for the APTT measured on a citrate tube drawn after a heparin tube. There was a small, but statistically significant bias on the APTT when the citrate tube was drawn as the first tube, after an EDTA tube or after a serum tube with clot activator. We consider this bias (max. 0.2 s) as not clinically significant. CONCLUSION: The order of draw has no significant influence on the PT/INR and APTT when measured on a Sarstedt citrate tube filled without the use of a discard tube or after a heparin, EDTA or serum tube with clot activator.

Periprocedural variations of platelet reactivity during elective percutaneous coronary intervention.

BACKGROUND: Percutaneous coronary intervention (PCI) modulates platelet reactivity (PR). OBJECTIVES: To assess: (i) the impact of coronary interventions on periprocedural variations (Δ) of PR; (ii) whether ΔPR correlates with periprocedural myocardial infarction (PMI); and (iii) the mechanisms of these variations in vitro. METHODS AND RESULTS: We enrolled 65 patients on aspirin (80-100 mg day(-1)) and clopidogrel (600 mg, 12 h before PCI): 15 with coronary angiography (CA group), 40 with PCI (PCI group), and 10 with rotational atherectomy plus PCI (RA group). PR was assessed by ADP, high-sensitivity ADP and thrombin receptor activator peptide 6 tests prior to, immediately after and 24 h after the procedure. E-selectin and ICAM-1 were assessed prior to and immediately after the procedure. In vitro, PR was measured during pulsatile blood flow at baseline, after balloon inflation and after stent implantation in six porcine carotid arteries and five plastic tubes. PR declined in the CA group, but significantly increased in the PCI and RA groups immediately postprocedure, and decreased to baseline at 24 h. ΔPR increased across the three groups (P < 0.0001). In the PCI group, ΔPR was directly related to total inflation time (r = 0.435, P = 0.005) and total stent length (r = 0.586, P < 0.001). The change in E-selectin significantly and inversely correlated with ΔPR (P < 0.001). No correlation was found with sICAM-1. PR increased significantly more in patients with PMI than in patients without PMI (P = 0.013). In vitro, platelet activation was observed in the presence of carotid arteries but not in the presence of plastic tubes. CONCLUSIONS: Despite dual antiplatelet therapy, PCI affected platelet function proportionally to procedural complexity and the extent of vascular damage.

Improved endocervical sampling and HPV viral load detection by Cervex-Brush Combi.

OBJECTIVE: Liquid-based cytology (LBC) for cervical screening is becoming increasingly used. Together with SurePath LBC, various collecting devices can be utilized, among which the Cervex-Brush is the most widely used. The new Rovers Cervex-Brush Combi combines the advantages of the Cervex-Brush with the EndoCervex-Brush increasing sampling of the endocervical canal. The objective of this study was to analyse and to compare the Cervex-Brush Combi with the Cervex-Brush for the collection of squamous and endocervical cells, human papillomavirus (HPV) typing/quantification and disease detection in SurePath LBC. METHODS: Using either the Cervex-Brush or the Cervex-Brush Combi 100 consecutive SurePath LBC samples were collected using each brush type. All 200 slides were read by the FocalPoint and screened by guided screening using slide wizards. The viral load of HPV type 16 E7, 18 E7, 31 E6, 33 L1, 33 E6, 35 E4, 39 E7, 45 E7, 51 E6, 52 L1, 52 E7, 53 E6, 56 E7, 58 L1, 58 E6, 59 E7, 66 E6 and 68 E7 was determined using a TaqMan-based real-time quantitative PCR analysis. RESULTS: The mean number of sampled squamous cells did not differ between the two brush types (54 963 versus 54 595 cells). The use of the Cervex-Brush Combi, however, resulted in a two- to threefold increase in the number of sampled endocervical cells (P < 0.00001). Using the Cervex-Brush Combi slightly more lesions were detected (three versus two low-grade squamous intraepithelial lesions), and resulted in the detection of more atypical squamous cells of undetermined significance (six versus three). In the Cervex-Brush group, 60% (3/5) of abnormal smears were positive for oncogenic HPV types, whereas 66.7% (6/9) of abnormal smears in the Cervex-Brush Combi group tested positive. The median HPV viral load for samples taken with the Cervex-Brush Combi was 0.1825 copies/cell and was significantly higher than in samples taken with the Cervex-Brush (0.0042 copies/cell) (P = 0.02). CONCLUSION: Sampling with the Cervex-Brush Combi resulted in the collection of the same amount of squamous cells, but in a two to threefold harvest of endocervical cells. This led to the detection of a higher viral load for oncogenic HPV and an increase in the number of detected abnormal smears.

Feasibility of a quality assurance programme of bedside blood glucose testing in a hospital setting: 7 years' experience.

AIMS: Description of the long-term use of a quality assurance (QA) programme for bedside capillary blood glucose (CBG) testing in a general hospital. METHODS: The main points of the programme were selection of instrumentation using a standardized testing procedure, design and implementation of a quality control (QC) procedure, and training and motivation of nurses. The QC procedures consisted of a daily aqueous control and a weekly split-sample control (a measurement on a capillary blood sample using the glucose meter and on a simultaneously drawn venous sample with the laboratory analyser). When the result was out of range, a laboratory technician visited the ward to investigate the problem. All wards received a weekly report. RESULTS: The programme was introduced in 1995 and followed up through 2002. The split-sample control was more efficient in detecting clinically relevant errors than the aqueous control. Most errors (91-97%) were operator-related rather than instrument-related. The compliance with the split-sample controls remained high, with 84-91% of weekly controls performed over 7 years. Respectively 91, 95 and 96% of the measurements remained within the range of +/- 20% of the laboratory value in the years 2000, 2001 and 2002. CONCLUSION: A QA programme of bedside CBG testing can successfully be implemented. It is feasible to obtain a satisfying level of measurement accuracy and to maintain a high level of compliance with the programme over several years. Split-sample controls are an essential part of the control procedure.