I Jennings

Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, England, United Kingdom

Are you I Jennings?

Claim your profile

Publications (61)240.44 Total impact

  • Source

    Full-text · Article · Nov 2015 · Thrombosis Research
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The 5th Haemophilia Global Summit was held in Barcelona, Spain, in September 2014. The programme was designed by an independent Scientific Steering Committee of haemophilia experts and explored issues relevant to the practical management of haemophilia, as well as key opportunities and challenges for care in the future. The topics outlined in this supplement were selected by the Scientific Steering Committee for their relevance to improving haemophilia care globally. In this supplement from the meeting, Gerry Dolan explores pharmacokinetics and dynamics in haemophilia, and Gerry Dolan and Ian Jennings jointly address the role of the laboratory in haemophilia care. The potential benefits of low-dose prophylaxis regimens for people with haemophilia in the developing world are reviewed by Jerzy Windyga, and the question of whether 'Future haemophilia research should be undertaken in the developing world' is debated by Jerzy Windyga and Cedric Hermans. Management strategies for ankle arthropathy are discussed by Sébastien Lobet and E. Carlos Rodríguez-Merchán, and the use of ultrasound for the early detection of haemophilic arthropathy is addressed by Matteo Nicola Dario Di Minno and Víctor Jiménez-Yuste. Finally, the role of patients in the future of haemophilia care is reviewed by Brian O'Mahony.
    Full-text · Article · Sep 2015 · European Journal Of Haematology
  • S. Kitchen · I. Jennings · R. Jones · D. Kitchen · T. Woods · I. Walker

    No preview · Conference Paper · Apr 2015

  • No preview · Conference Paper · Apr 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Point-of-care (POC) testing within hemostasis is an expanding field, with the most widely used test being POC international normalized ratio (INR). Many of these devices are being used in a nonlaboratory setting by staff with no laboratory training. In the United Kingdom, external quality assessment (EQA) is provided by the organization UK National External Quality Assessment Scheme for Blood Coagulation (UK NEQAS BC). Participants within the UK NEQAS BC POC INR program are largely based in primary care (77%), with the majority of EQA samples and patients tests being performed by nurses (70%). Many of these centers do not have support from the laboratory staff and may, therefore, not understand the requirement for a robust quality control (QC) system comprising both internal quality control (IQC) and EQA. From data acquired through a questionnaire of these UK NEQAS BC users, we observed that 2% of the centers never perform IQC tests, only 29% perform IQC tests when starting a new batch of test strips, and just 15% carry out IQC with each clinic as recommended by the UK guidelines. The imprecision of EQA tests was greater for POC users than in the UK NEQAS BC hospital laboratory program, with average coefficients of variation for a 2-year period of 11.0 and 7.3%, respectively. This may reflect the handling of EQA samples rather than the imprecision of the method, due to the lack of laboratory training amongst POC staff. POC INR in the UK could greatly benefit from more interaction and support from laboratories to these POC testers. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
    No preview · Article · Mar 2015 · Seminars in Thrombosis and Hemostasis
  • [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionExternal quality assessment (EQA) is an important component of quality assurance for laboratory tests of haemostasis. Lyophilization of plasma confers stability of labile clotting factors, allowing valid comparison of results between participating centres. However, elevated ambient temperatures in some geographical areas could affect the stability of lyophilized samples in transit.Methods The effect on lyophilized plasma samples of consistent elevated temperature with respect to haemostasis tests was determined in a single centre. The temperature to which packages were exposed during transit was also monitored.ResultsSurvey packages were exposed to average temperatures up to 31.9 °C and maximum temperatures up to 39.7 °C over delivery periods between 1 and 8 weeks. In-house studies revealed samples to be stable over a 6-week period at a constant 30 °C, and only small changes were observed for samples exposed to 37 °C for 4 weeks. 6-week storage at 37 °C was associated with average changes of up to 15% in factor assay activity.Conclusion Lyophilized EQA material employed in UK NEQAS surveys is stable under conditions encountered for the majority of participants, but in cases of delayed delivery of samples, the effect of temperature on sample integrity must be considered when assessing laboratory performance.
    No preview · Article · Dec 2014 · International journal of laboratory hematology
  • Source

    Full-text · Article · Aug 2014 · British Journal of Haematology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Molecular genetic analysis of families with hemophilia and other heritable bleeding disorders is a frequently requested laboratory investigation. In the United Kingdom, laboratories undertaking genetic testing must participate in a recognized external quality assessment scheme for formal accreditation. The UK National External Quality Assessment Scheme (UK NEQAS) for heritable bleeding disorders was established in its current format in 2003, and currently has 27 registered participants in the United Kingdom, the European Union (EU), and the non-EU countries. Two exercises per annum are circulated to participants comprising either whole blood or DNA isolated from cell lines, and laboratories are allowed 6 weeks to analyze the samples and generate a report. Reports are assessed by a panel comprising clinicians and scientists with expertise in this area. Samples to date have involved analysis of the F8 gene (10 exercises), the F9 gene (4 exercises), and the VWF gene (3 exercises) and have comprised a wide spectrum of mutations representing the routine workload encountered in the molecular genetics laboratory. The majority of laboratories in each exercise passed, but a small number did not and reasons for failing included clerical errors, genotyping inaccuracies, and a failure to correctly interpret data. Overall we have seen an improvement in quality of reports submitted for assessment, with a more concise format that will be of value to referring clinicians and counsellors. Informal feedback from participants has been very positive.
    Full-text · Article · Feb 2014 · Seminars in Thrombosis and Hemostasis
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A diagnosis of hemophilia A or hemophilia B begins with clinical assessment of the patient and is facilitated by laboratory testing. The influence of the latter on a diagnosis of hemophilia A or hemophilia B is clear-a diagnosis cannot be made without laboratory confirmation of a deficiency of factor FVIII (FVIII) or factor IX (FIX), respectively. Moreover, the degree of hemophilia severity is specifically characterized by laboratory test results. In turn, patient management, including choice and application of therapies, is influenced by the diagnosis, as well as by identification of respective disease severity. An incorrect diagnosis may lead to inappropriate management and unnecessary therapy, and thus to adverse outcomes. Moreover, identification of factor inhibitors in hemophilia will lead to additional and differential treatments, and incorrect identification of inhibitors or inhibitor levels may also lead to inappropriate management. Problems in hemophilia diagnosis or inhibitor detection can occur at any stage in the clinical diagnosis/laboratory interface, from the "pre-preanalytical" to "preanalytical" to "analytical" to "postanalytical" to "post-postanalytical." This report outlines the various problems in laboratory testing for hemophilia and provides various strategies or solutions to overcome these challenges. Although some outlined solutions are specific to the potential errors related to hemophilia, others are general in nature and can be applied to other areas of laboratory hemostasis. Key to improvement in this area is adoption of best practice by all involved, including clinicians, phlebotomists, and laboratories. Also key is the recognition that such errors may occur, and thus that clinicians should assess laboratory test results in the context of their patient's clinical history and follow-up any potential errors, thus avoid misdiagnoses, by requesting repeat testing on a fresh sample.
    Full-text · Article · Sep 2013 · Seminars in Thrombosis and Hemostasis
  • Source

    Full-text · Article · Jul 2013 · British Journal of Haematology
  • Isobel D. Walker · Ian Jennings
    [Show abstract] [Hide abstract]
    ABSTRACT: Testing for heritable thrombophilia usually includes chromogenic assays of antithrombin and protein C activity, an immunologic assay of free protein S and tests for the factor V Leiden mutation and the prothrombin G20210A polymorphism. Other tests such as a clotting assay of protein C, homocysteine assay or fibrinogen studies may occasionally be considered but in general these are the province of specialist laboratories. Testing should be limited to carefully selected patients and, when antithrombin, protein C and protein S are to be assayed, attention paid to timing sample collection to avoid misdiagnosis resulting from acquired deficiency due to physiological or pathological conditions or their management. It is of paramount importance that the results of the tests are interpreted by someone who knows the clinical details of the individual from whom the sample was taken and understands the limitations of the laboratory tests.
    No preview · Chapter · Feb 2013
  • I Jennings · D P Kitchen · S Kitchen · T A L Woods · I D Walker
    [Show abstract] [Hide abstract]
    ABSTRACT: Introduction: The APTT is widely employed as part of a coagulation screening panel, used as a pre-operative assessment of bleeding risk, to detect hereditary and acquired haemostatic defects and to monitor anticoagulant therapy. External quality assessment (EQA) exercises assess laboratory performance of individual tests, but rarely assess the approach to investigation of an abnormal result. Methods: A multicentre exercise was carried out to investigate the ability of laboratories to identify the cause of a prolonged APTT. A sample was distributed with a request to carry out whichever tests were considered necessary to achieve a probable diagnosis. Results: One hundred and ten centres in the UK NEQAS programme took part, and all 104 centres providing an interpretation correctly identified deficiency of FVIII in the sample. However, of these, 10 centres reported additional defects, including lupus anticoagulant, FIX deficiency, FXII deficiency and a FVIII inhibitor. Conclusions: A markedly varied approach to investigation of a prolonged APTT was observed, although a lack of clinical information may have contributed to this finding.
    No preview · Article · Nov 2012 · International journal of laboratory hematology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background Vitamin K antagonists have been used for many decades and have been traditionally monitored by the measurement of the International Normalised Ratio (INR) in the laboratory. Introduction of Point of Care (POC) testing devices to measure INR has resulted in many tests being undertaken in primary care. External Quality Assessment (EQA) of these POC devices is recommended to ensure accuracy and reliability of INR results outside a laboratory setting. Aim To assess the quality of INR results for users of two POC devices (CoaguChek XS and CoaguChek XS Plus) over a four-year period. Methods Four surveys (two samples) were sent in each 12-month period. The median INR value of each sample was calculated and the percentage deviation from this median determined. Any results greater than 15% from the median were considered to be outside consensus which indicated a possible problem within the testing system. Results Variability of INR results in this UK National External Quality Assessment Scheme (NEQAS) programme was comparable to that in the UK NEQAS EQA programme for laboratory INR testing. Occurrence of persistent problems was lower in the POC programme than the laboratory programme. Conclusions Utilisation of an EQA programme for POC devices in primary care is feasible and necessary. Our data suggest for those health professionals using EQA, the reliability and accuracy of INR testing matches the quality of laboratory testing.
    No preview · Article · Oct 2012 · Journal of clinical pathology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Congenital defects of platelets or plasma proteins involved in blood coagulation generally lead to bleeding disorders. In some of these disorders, patients with a severe phenotype are prone to spontaneous bleeds with critical consequences. This situation occurs more commonly in haemophilia A and haemophilia B and to a certain extent in severe forms (type 3) of von Willebrand disease. Defects in other plasma coagulation proteins and platelet factors are relatively rare, with an incidence of ≤ 1: 1-2 million. Molecular genetic studies of the human coagulation factors, especially factors VIII and IX, have contributed to a better understanding of the biology of these genetic disorders, the accurate detection of carriers and genetic counselling, and have also fostered new therapeutic strategies. This article reviews the evolution of genetics over the last five decades as a tool for bleeding disorder investigations, the recent advances in molecular techniques that have contributed to improved genetic diagnosis of this condition, and the development and utility of proficiency testing programmes and reference materials for genetic diagnosis of bleeding disorders.
    Full-text · Article · Jul 2012 · Haemophilia
  • [Show abstract] [Hide abstract]
    ABSTRACT: von Willebrand disease (VWD) is the most common inherited bleeding disorder, but variable severity and several classification types mean that diagnosis is often not straightforward. In many countries, the assays are not readily available and/or are not well standardized. The latest methods and the basis of VWD are discussed here, together with information from the international quality assessment programme (IEQAS). Factor XIII deficiency is a rare, but important bleeding disorder, which may be missed or diagnosed late. A discussion and update on this diagnosis is considered in the final section of our review.
    No preview · Article · Jul 2012 · Haemophilia
  • Source
    D P Kitchen · S Kitchen · I Jennings · T A L Woods · I D Walker
    [Show abstract] [Hide abstract]
    ABSTRACT: See also Shermock KM, Kraus P, Streiff MB. Novel analysis of clinically relevant diagnostic errors in point-of-care devices: a reply to a rebuttal. This issue, pp 1192-4; Shermock KM, Streiff MB, Pinto BL, Kraus P, Pronovost PJ. Novel analysis of clinically relevant diagnostic errors in point-of-care devices. J Thromb Haemost 2011; 9: 1769-75.
    Preview · Article · Jun 2012 · Journal of Thrombosis and Haemostasis

  • No preview · Article · Jan 2012
  • Source
    I Jennings · S Kitchen · D P Kitchen · T A L Woods · I D Walker

    Preview · Article · Jul 2011 · Journal of Thrombosis and Haemostasis
  • [Show abstract] [Hide abstract]
    ABSTRACT: The quality of anticoagulation management is not readily or frequently assessed, particularly between different centres. This study sought to evaluate agreement in oral anticoagulant management decisions between participating centres in UK NEQAS programmes. Participants were asked to indicate whether they used computerized dosing support software (CDSS) and to complete a series of questions with respect to anticoagulant management provision. Four clinical scenarios were provided, together with past and current International Normalised Ratio (INR) results. Participants were asked to provide recommendations on the target INR they would assign to the patient, the dose of warfarin and a recall interval. Seven hundred and fifty-nine centres returned results, of which 28% were enrolled in the hospital-based EQA programme, and 72% were participants in the point-of-care testing programme. Six hundred (79%) reported use of CDSS. In one straightforward scenario, there was 99% agreement in dose recommendation. However, for three more complex scenarios, differences were apparent in target INRs employed and both dose and recall recommendations. In some cases, differences related to the software system employed. The study emphasizes large variation in the approach to managing these scenarios and warrants further investigation, together with education including promoting national guidelines for the assignment of target ranges.
    No preview · Article · Jul 2011 · International journal of laboratory hematology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Global hemostasis devices are currently being employed in operating rooms to assess the bleeding risk and outcomes for patients undergoing surgery. Two devices currently available are the TEG (Thromboelastograph; Haemoscope Corp., Niles, IL) and the ROTEM (Rotation Thromboelastometer; Pentapharm GmbH, Munich, Germany). Both measure the speed of clot formation, the strength of the clot when formed, and clot fibrinolysis kinetics. The two devices use different parameters so no cross comparisons of results can be made. The devices are usually operated by a member of the operating team and not a laboratory scientist; thus their testing and performance is generally not laboratory controlled, despite quality control being required to ensure reliable results. The UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation has undertaken a series of exercises evaluating the provision of External Quality Assessment (EQA) material for these devices. A series of four studies have taken place using lyophilized plasmas as the test material. Up to 18 TEG users and 10 ROTEM users have been involved in testing two samples per study, for a total of eight samples tested. The samples were normal plasmas, factor VIII or XI deficient samples, or normal plasmas spiked with heparin. The precision of the tests varied greatly for both devices, with coefficients of variances ranging from 7.1 to 39.9% for TEG and 7.0 to 83.6% for ROTEM. Some centers returned results that were sufficiently different from those obtained by other participants to predict alterations in patient management decisions. Our data indicate that regular EQA/proficiency testing is needed for these devices.
    Preview · Article · Oct 2010 · Seminars in Thrombosis and Hemostasis