The clinical significance of differences between point-of-care and laboratory INR methods in over-anticoagulated patients

INTRODUCTION

Patients receiving warfarin are at increased risk of bleeding when their International Normalised Ratio (INR) >4.5. Although not standardised above 4.5 the INR is measured in over-anticoagulated patients, consequently we have examined the reliability of INR results ≥4.5. We assessed: the relationship between different prothrombin time systems for INRs >4.5; the relationships between the INR and levels of vitamin K-dependent coagulation factors (VKD-CF) and thrombin generation test (TGT) parameters; and the impact that variation in results would have on warfarin dosing.

METHODS

INRs were performed using a CoaguChek XS Plus point-of-care (POC) device (measuring range 0.6-8.0). For POC INRs ≥4.5, laboratory INRs were also measured using a recombinant tissue factor (rTF) and a rabbit brain (RBT) thromboplastin.

RESULTS

There was good correlation between POC (INR ≥4.5, <8.0) and Lab INRs (rTF n=154, rs=0.87, p<0.0001; RBT n=102, rs=0.76, p<0.0001); and significant correlations between each of the VKD-CF and the INR, the strongest being with FVII (POC INR rs=-0.53 p<0.0001; Lab rTF-INR rs=-0.70 p<0.0001). TGT peak thrombin and ETP also showed good correlations with INR values (R(2)>0.71). Using POC and Lab rTF-INR, 109/154 (71%), or POC and Lab RBT-INR 75/102 (74%) results exhibited dosage concordance and/or were within 0.5 INR units. In the remaining patients variation in warfarin dosing was generally slight.

CONCLUSIONS

Our data suggest that CoaguChek XS Plus INRs >4.5 and <8.0 are comparable to laboratory INRs (both methods) and it is probably unnecessary to perform laboratory INRs for clinical management of patients with INRs >4.5 including those >8.0.

TEM Study of MOCVD Grown InSb/GaAs Heterostructures with and without TMIn Predeposited Layers

High quality InSb epilayers were grown on GaAs substrates by metal organic chemical vapor deposition using a two-step growth procedure involving trimethal indium (TMIn) predeposition. From transmission electron microscopy studies, we found that an interdiffusion layer of thickness of 10 Å forms at the interface when the substrate is exposed to TMIn for approximately 6 secs prior to the growth of the InSb filns. Hall mobilities up to σ 52,000 cm2/V-s were obtained at 300 K on a 2.1-μm-thick InSb heteroepitaxial film. In contrast, samples without TMIn predeposition showed polycrystallinity of the InSb films grown on single crystalline GaAs substrates. The effect. of TMNIn predeposition is to minimize the misorientation of the grains, suppress the polycrystallinity, decrease the density of threading dislocations, and increase the electron mobilities in the films. However, we found that too much TMIn predeposition gives rise t.o an intermixing layer at the InSb/GaAs interface which deteriorates the film quality. Details of the effect of the TMIn predeposition on the microstructure of InSb/GaAs with different predeposition times (zero, 6, and 12 secs) are discussed.

The effect of prion reduction in solvent/detergent-treated plasma on haemostatic variables

BACKGROUND

Octapharma PPGmbH has recently modified its manufacturing process for solvent/detergent-treated plasma to incorporate a prion reduction step, in which a 3 log reduction has been demonstrated. The current study was undertaken to assess the impact of this procedure on haemostatic variables in the new product OctaplasLG in comparison with standard Octaplas.

METHODS

Production batches of standard Octaplas (n=4) and OctaplasLG (n=16) were assessed for levels of coagulation factors, physiological protease inhibitors, markers of activation and procoagulant microparticles. Global haemostasis was assessed by a thrombin generation test (TGT) and rotational thromboelastometry (ROTEM).

RESULTS

Mean levels of factors: II, V, VII, IX, X, XI, XII and XIII, VWF:Ag, antithrombin, protein C and free protein S were all >75 u/dl. ADAMTS-13 activity levels were normal. Factor VIII and VWF:RCo were >55 u/dl. TGT and ROTEM were similar in both preparations, and microparticles were present at negligible levels. Two units of OctaplasLG had slightly elevated levels of Prothrombin Fragments 1+2, but D-Dimer and thrombin-antithrombin complexes were normal in all batches.

CONCLUSION

These studies indicate that the affinity chromatography procedure used in OctaplasLG does not appear to adversely affect the proven haemostatic quality of Octaplas, while offering a selective reduction in the concentration of pathological prion proteins.

The effect of skin conditions on patients' quality of life

Skin conditions can adversely affect many aspects of patients' lives. The quality of life for people with skin conditions such as psoriasis, atopic eczema and acne can be significantly impaired in terms of their psychological wellbeing, social functioning and everyday activities. The significant psychological and social morbidity that occurs in patients with common skin conditions may go unrecognised without appropriate assessment. The level of psychosocial morbidity associated with skin disorders may be underestimated by health professionals.

Identification of a novel cell type-specific intronic enhancer of macrophage migration inhibitory factor (MIF) and its regulation by mithramycin

The aim of this study was to determine the genetic regulation of macrophage migration inhibitory factor (MIF). DNase I hypersensitivity was used to identify potential hypersensitive sites (HS) across the MIF gene locus. Reporter gene assays were performed in different human cell lines with constructs containing the native or mutated HS element. Following phylogenetic and transcription factor binding profiling, electrophoretic mobility shift assay (EMSA) and RNA interference were performed and the effects of incubation with mithramycin, an antibiotic that binds GC boxes, were also studied. An HS centred on the first intron of MIF was identified. The HS acted as an enhancer in human T lymphoblasts (CEMC7A), human embryonic kidney cells (HEK293T) and human monocytic cells (THP-1), but not in a fibroblast-like synoviocyte (FLS) cell line (SW982) or cultured FLS derived from rheumatoid arthritis (RA) patients. Two cis-elements within the first intron were found to be responsible for the enhancer activity. Mutation of the consensus Sp1 GC box on each cis-element abrogated enhancer activity and EMSA indicated Sp1 binding to one of the cis-elements contained in the intron. SiRNA knock-down of Sp1 alone or Sp1 and Sp3 together was incomplete and did not alter the enhancer activity. Mithramycin inhibited expression of MIF in CEMC7A cells. This effect was specific to the intronic enhancer and was not seen on the MIF promoter. These results identify a novel, cell type-specific enhancer of MIF. The enhancer appears to be driven by Sp1 or related Sp family members and is highly sensitive to inhibition via mithramycin.

Factor XIII--an under diagnosed deficiency--are we using the right assays?

BACKGROUND

  The clot solubility test is the most widely used method for detection of factor (F)XIII deficiency. However, it will only detect severe deficiencies; consequently mild deficiencies and heterozygous states are probably under diagnosed.

OBJECTIVE

As an alternative first-line screening test, we assessed an automated quantitative ammonia release assay (QARA).

PATIENTS/METHODS

Inter-assay imprecision was evaluated with commercial normal and pathological control plasmas (10 replicates on each of 5 days). Using the QARA and other commercial assays a comparative assessment of congenital (FXIII range < 1-70 u dL(-1), n = 9) and acquired (n = 43) deficiencies was made. We also investigated the prevalence of acquired deficiencies in hospitalized patients using residual samples from adult patients (n = 1004) and from a paediatric intensive care unit (ICU, n = 56).

RESULTS

Assay imprecision was acceptably low (normal control: mean 86.6 u dL(-1); cv = 2.0%; pathological control: mean 27.5 u dL(-1); cv = 3.8%). Using an iodoacetamide blanking procedure, the QARA results (FXIII range < 1-70 u dL(-1)) exhibited close agreement with those from an immuno-turbidometric FXIII A-subunit (FXIII-A) method. There was also good correlation (R(2) ≥ 0.89) between the QARA (range 20-180 u dL(-1)), a second chromogenic assay, the FXIII-A and FXIII A+B-subunit ELISA. We found that 21% of samples from adult patients had FXIII levels < 70 u dL(-1) (mean normal ± 2 SD 73-161 u dL(-1)) with 6% < 50 u dL(-1). Within the paediatric ICU samples, 52% were < 70 u dL(-1), with 21% < 50 u dL(-1).

CONCLUSIONS

Our data demonstrates that the automated assay is sensitive, highly reproducible and the results from clinical samples suggest that acquired FXIII deficiency is a relatively common phenomenon in hospital patients after surgery and in ICU.

Exploring the needs and expectations of women presenting for hysterosalpingogram examination following a period of subfertility: a qualitative study

AIMS

This study examines women's experience of healthcare following the referral for hysterosalpingography (HSG) after a period of subfertility. These otherwise fit and healthy women enter the healthcare system and their only problem is a failure to become pregnant. They find themselves trying to negotiate a system designed for sick people. Previous research in this field consists mainly of studies comparing HSG to other diagnostic studies. The study aims to address the underlying issues that women have at the start of their subfertility investigations.

METHODS

This qualitative study uses grounded theory methodology. Interviews with women were undertaken immediately prior to their HSG examination. Ten women were interviewed using 12 core questions. Each woman had a diagnosis of primary subfertility. Each was asked how they were coping with the uncertainty of their fertility. They were asked about their expectations of the HSG examination, the importance of HSG and what methods were available to them to reduce any anxiety experienced. Data analysis was undertaken after each interview.

RESULTS

Presently, HSG is seen by healthcare providers as a routine outpatient examination at the start of subfertility investigations. In contrast to this, it was discovered at interview that HSG was seen by the women as a defining moment that would signpost their future treatment options to become pregnant. Women reported receiving little support from health care providers, and that written information given did not fulfil all of their needs. Often written information alone heightened anxiety, and this written information needs to be tailored to a specific set of circumstances. The literature review noted that anxiety can lead to mental health issues, but that properly focused, correctly given, timely information can reduce anxiety.

CONCLUSIONS

The implications of the findings are that if anxiety relating to treatment at this early stage can be managed effectively, it could minimise the possible physical and emotional trauma to the woman as her subfertility journey continues, thus at the same time preventing future anxiety related illness.