19 research outputs found

    Critical value reporting : A survey of 36 clinical laboratories in South Africa

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    KMObjective: Critical value policies are used by clinical laboratories to decide when to notify caregivers of life-threatening results. Despite their widespread use, critical value policies have not been published locally. A survey was designed to determine critical value policies for haematology tests in South Africa. Methods: A survey was carried out on 136 identified laboratories across South Africa in January 2013. Of these, 36 responded. Data collected included critical value policies, critical values for haematology parameters, and critical value reporting. Results: Of the 36 laboratories surveyed, 11.1% (n=4) were private, 33.3% (n=12) were affiliated to academic institutions and 55.6% (n=20) were peripheral or regional National Health Laboratory Service laboratories. All the laboratories confirmed that they had a critical value policy, and 83.3% of such policies were derived from local clinical opinion. Mean low and high critical limits for the most frequently listed tests were as follows: haemoglobin 20 g/dl, platelet count 1 000 ×109 /l, white cell count 46×109 /l, activated partial thromboplastin time >101 seconds, and international normalised ratio >6. In almost all cases critical value reporting was performed by the technologist on duty (97.2%). The majority of laboratories required that the person notified of the critical value be the doctor who ordered the test or the caregiver directly involved in the patient’s care (83.3%); 73.3% of laboratories indicated that they followed an algorithm if the doctor/caregiver could not be reached. Conclusion: Each laboratory is responsible for establishing clinically relevant critical limits. Clinicians should be involved in developing the laboratory’s critical value policy. The findings of this survey may be of value to local laboratories that are in the process of establishing or reviewing critical value policie

    Point-of-care estimation of haemoglobin concentration in all age groups in clinical practice

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    Background: The measurement of haemoglobin (Hb) concentration provides a reliable, primary screening test for the presence and severity of anaemia. The HemoCue® is a point-of-care test for Hb measurement. The introduction of point-of-care testing in hospitals and general practice has improved patient care and accessibility. This study was performed to evaluate the utility of point-of-care Hb measurement with the HemoCue® device for the diagnosis of anaemia. Method: In this prospective study, we compared the analytical performance of the HemoCue® to the Coulter® LH 750 automated haematology analyser with regard to accuracy, precision and linearity in the measurement of Hb in adult and paediatric patient samples, referred for routine laboratory testing. Results: Samples from 100 patients were analysed with both instruments, and the results were compared using standard scatter and difference plots. The mean Hb value of the HemoCue® (11.3 g/dl; range 4.6-16.7) was comparable to the Coulter® LH 750 (11.3 g/dl; range 4.7-17.2). The Bland-Altman difference plot revealed good correlation. Bias between the two methods was small, and the imprecision was within acceptable limits. Hb measurement was linear in the range of 4.8-20 g/dl. Conclusion: In all age groups, the HemoCue® point-of-care device can be used to provide accurate and reliable Hb measurements with a smaller sample volume, improved turnaround time, and long-term cost saving.Keywords: haemoglobin, HemoCue®, point-of-care testing, anaemia screenin

    Validation of the CoaguChek XS international normalised ratio point-of-care analyser in patients at Charlotte Maxeke Johannesburg Academic Hospital, South Africa

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    Background. Measurement of the international normalised ratio (INR) is essential in the management of patients on long-term warfarin therapy. The CoaguChek XS portable coagulometer is a point-of-care test for INR measurement. It offers the advantage of improved patient accessibility, particularly in peripheral clinics.Objectives. To evaluate the clinical utility of the CoaguChek XS for monitoring of patients on standard warfarin therapy (INR 2 - 3) as well as those with mechanical heart valve replacements (INR 2.5 - 3.5).Methods. We compared the performance of the CoaguChek XS device with that of the STAGO laboratory analyser with regard to accuracy and precision in 304 patients referred for routine testing.Results. The mean INR value of the CoaguChek XS of 2.75 (standard deviation (SD) 1.18) was comparable to that of the STAGO (2.65 (SD 1.04)). The Bland Altman difference plot revealed good agreement. Bias between the two methods was small, and the imprecision was within acceptable limits. Within the target range (2.0 - 3.5), 93.9% of the CoaguChek XS INR readings were within 0.5 units of the standard laboratory method result. There was, however, an increase in the variability of the differences between the two test methods when the INR was >3.6.Conclusion. The CoaguChek XS point-of-care device can be used to provide accurate and precise INR measurements over a wide range for monitoring of valvular and non-valvular patients on long-term warfarin therapy

    Thrombo-embolic and bleeding complications in patients with mechanical valve replacements - a prospective observational study

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    Background and objectives. Long-term anticoagulation therapy is essential to prevent thrombo-embolic events in patients with mechanical valve replacements. In order to offer indigent patients mechanical heart valve replacement surgery, dedicated anticoagulation clinics are necessary for follow-up. This study assessed the safety and efficacy of lifelong oral anticoagulation therapy in Johannesburg General Hospital mechanical heart valve replacement recipients. The incidence of bleeding and thrombo-embolic complications was documented in three groups of patients with mechanical valve replacements. The groups included patients with aortic valve replacements (AVRs), mitral valve replacements (MVRs) and double (aortic and mitral) valve replacements (DVRs). Materials and methods. A prospective observational study was conducted over a 4-month period. Data on 306 patients attending the Johannesburg General Hospital anticoagulation clinic between 2000 and 2005 were analysed. Of the total patients selected, 205 were assigned to the mechanical valve replacement group (which included 63 patients with AVRs, 93 with MVRs and 49 with DVRs); a control group of 101 nonmechanical valve replacement patients were also included. At each visit the level of anticoagulation was assessed from the international normalised ratio (INR) values, and the presence of bleeding and / or thrombo-embolic complications was documented. Results. There were a total of 51 bleeding and thrombo-embolic complications in the study population. Patients with DVRs had a higher proportion of combined complications (30.61%) than patients with single valve replacements (14.29% in the AVR group and 18.05% in the MVR group) and patients in the control group (12.87%). There were 38 bleeding complications, 30 minor and 8 major. Twelve thrombo-embolic events were documented. Individually, there was no significant difference in thrombo-embolic and bleeding complications between the subgroups. Eighty-two per cent of patients in the mechanical valve replacement group were within the therapeutic range for anticoagulant control (INR 2.5 - 3.5) v. 54% in the control group (INR 2.0 - 3.0). Anticoagulant control was of a high quality and was not a contributing factor to the incidence of bleeding and / or thrombo-embolic complications. Conclusion. The finding of a low incidence of bleeding and thrombo-embolic complications in patients with mechanical valve replacements supports the continued placement of mechanical valves in our setting and use of oral anticoagulation therapy at an INR of 2.5 - 3.5. However the increased risk of both bleeding and thrombo-embolic complications in the DVR group is cause for great concern and warrants further investigation. South African Medical Journal Vol. 96(8) 2006: 710-71

    Thrombotic disorders (part 1)

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    Thromboembolic conditions are the leading cause of mortality, estimated to account for 1 in 4 deaths worldwide in 2010. Over time, the incidence and mortality rates of these conditions have improved in developed countries, but are increasing in developing countries. The haemostatic system comprises 6 main components, i.e. (i) platelets; (ii) vascular endothelium; (iii) coagulation proteins; (iv) natural anticoagulants; (v) the fibrinolytic system; and (vi) natural antifibrinolytic factors. A delicate balance exists between procoagulant and anticoagulant factors within the vascular system. Numerous acquired or inherited conditions may tip the balance either way, i.e. towards a prothrombotic or prohaemorrhagic state. In this issue of CME, the first of a 2-part series on thrombophilic disorders, the subject of discussion is on inherited varieties that the general practitioner is likely to encounter. This review is primarily based on venous thrombosis

    Gaucher disease: A cause of massive splenomegaly in a 15-year-old black African male

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    Patients with Gaucher disease (GD), a rare autosomal recessive lysosomal storage disease, commonly present to paediatricians with massive splenomegaly. While the diagnosis and management of patients with this chronic multisystem disorder has evolved significantly in recent years, the initial diagnosis represents a challenge. We describe the case of a 15-year-old black African male who presented with abdominal distension, delayed growth and fatigue. Initial laboratory studies revealed severe anaemia (haemoglobin concentration 8 g/dL) and moderate thrombocytopenia (platelet count 80 Ă— 109/L). A computed tomography scan of the abdomen showed an enlarged liver of 173 mm and massive splenomegaly of 27 mm. The diagnosis of GD was confirmed by reduced beta-glucocerebrosidase activity and heterozygous mutations in the GBA1 gene. The patient was managed at a dedicated paediatric haematology unit with enzyme replacement therapy and regular clinical, biochemical and radiological monitoring

    Inherited bleeding disorders

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    Abnormal bleeding is a common clinical presentation in general practice, and a rational approach to this problem is therefore required. Investigation of a suspected bleeding disorder necessitates a comprehensive history, thorough physical examination and systematic laboratory work-up. Inherited bleeding disorders (IBDs) typically manifest in childhood, but may present later in life after a haemostatic challenge (such as trauma, surgery, tooth extraction). This two-part CME series is intended to provide insight to the medical practitioner on the clinical spectrum, diagnosis and management of bleeding disorders. Bleeding due to inherited disorders is the subject of discussion in part 1 (current issue), and in part 2 (forthcoming issue) the focus is on bleeding from acquired causes. Patients diagnosed with an IBD should ideally be referred to a dedicated tertiary healthcare facility, e.g. haemophilia centre, for management and follow-up

    Venous thromboembolism: Prophylactic and therapeutic practice guideline

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    Background. Pharmacological prophylactic anticoagulation in many countries, including South Africa, is under-prescribed. This has resulted in unacceptable rates of morbidity and mortality. Method. The Southern African Society of Thrombosis and Haemostasis held a meeting to update the previous guideline and review new literature including guidelines from other societies. The following specialties were represented on the committees: anaesthetics, cardiology, clinical haematology, critical care, obstetrics and gynaecology, haematopathology, internal medicine, neurology, orthopaedic surgery and pulmonology. A draft document was presented at the meeting, which was then revised by consensus agreement. To avoid local bias, the guideline was adjudicated by recognised international external experts. Results and conclusion. A concise, practical updated guideline for thromboprophylaxis and treatment in medical and surgical patients has been produced for South African conditions. It is hoped that this guideline will continue to improve anticoagulation practice in this country, which we believe will directly benefit patient outcomes

    Recommendations for the diagnosis and management of vaccine-induced immune thrombotic thrombocytopenia

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    There have recently been safety concerns regarding an increased risk of vaccine-induced immune thrombotic thrombocytopenia (VITT) following administration of SARS-CoV-2 adenoviral vector vaccines. The Southern African Society of Thrombosis and Haemostasis reviewed the emerging literature on this idiosyncratic complication. A draft document was produced and revised by consensus agreement by a panel of professionals from various specialties. The recommendations were adjudicated by independent international experts to avoid local bias. We present concise, practical guidelines for the clinical management of VITT
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