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Rationale: To examine the potential of TLR9 (Toll-like receptor 9) activation to modulate the type 2 immune response in asthma.Objectives: To evaluate efficacy and safety of AZD1419, an inhaled TLR9 agonist, in a phase 2a, randomized, double-blind trial.Methods: Adult patients with asthma with a history of elevated eosinophils (>250 cells/µl) were randomized 1:1 to receive 13 once-weekly doses of inhaled AZD1419 (1, 4, or 8 mg; n = 40) or placebo (n = 41). Inhaled corticosteroids and long-acting ß2-agonist were tapered down and then discontinued. The last four doses of AZD1419 were given without maintenance medication, followed by a 40-week observation period. Primary endpoint was time to loss of asthma control (LOC).Measurements and Main Results: AZD1419 induced a T-helper cell type 1-type IFN response with a sustained reduction in markers of type 2 inflammation. However, there were no statistically significant differences between AZD1419 and placebo for time to LOC, proportion of patients with LOC, changes in Asthma Control Questionnaire-five-item version, exacerbations, reliever use, FEV1, peak expiratory flow, or fractional exhaled nitric oxide (FeNO). LOC was predicted by an early rise in FeNO in 63% of patients. Despite withdrawal of maintenance treatment, 24 patients completed the study without LOC; AZD1419 n = 11, placebo n = 13. Adverse events were balanced across groups, with no deaths or serious adverse events judged as causally related to AZD1419.Conclusions: AZD1419 was safe and well tolerated but did not lead to improved asthma control, despite reducing markers of type 2 inflammation. Results suggest that a novel accelerated step-down approach based on FeNO is possible for patients with well-controlled asthma.
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Antiasmáticos/uso terapéutico , Asma/tratamiento farmacológico , Oligonucleótidos/uso terapéutico , Receptor Toll-Like 9/uso terapéutico , Administración por Inhalación , Adulto , Anciano , Antiasmáticos/administración & dosificación , Asma/inmunología , Método Doble Ciego , Femenino , Humanos , Factores Inmunológicos/uso terapéutico , Masculino , Persona de Mediana Edad , Receptor Toll-Like 9/agonistas , Receptor Toll-Like 9/efectos de los fármacos , Resultado del TratamientoRESUMEN
The heterogeneous manifestations of MYH9-related disorder (MYH9-RD), characterized by macrothrombocytopenia, Döhle-like inclusion bodies in leukocytes, bleeding of variable severity with, in some cases, ear, eye, kidney, and liver involvement, make the diagnosis for these patients still challenging in clinical practice. We collected phenotypic data and analyzed the genetic variants in more than 3,000 patients with a bleeding or platelet disorder. Patients were enrolled in the BRIDGE-BPD and ThromboGenomics Projects and their samples processed by high throughput sequencing (HTS). We identified 50 patients with a rare variant in MYH9. All patients had macrothrombocytes and all except two had thrombocytopenia. Some degree of bleeding diathesis was reported in 41 of the 50 patients. Eleven patients presented hearing impairment, three renal failure and two elevated liver enzymes. Among the 28 rare variants identified in MYH9, 12 were novel. HTS was instrumental in diagnosing 23 patients (46%). Our results confirm the clinical heterogeneity of MYH9-RD and show that, in the presence of an unclassified platelet disorder with macrothrombocytes, MYH9-RD should always be considered. A HTS-based strategy is a reliable method to reach a conclusive diagnosis of MYH9-RD in clinical practice.
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Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Variación Genética , Secuenciación de Nucleótidos de Alto Rendimiento , Cadenas Pesadas de Miosina/genética , Adolescente , Adulto , Anciano , Alelos , Niño , Preescolar , Mapeo Cromosómico , Evolución Molecular , Femenino , Técnica del Anticuerpo Fluorescente , Expresión Génica , Estudios de Asociación Genética/métodos , Genotipo , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Humanos , Lactante , Masculino , Persona de Mediana Edad , Mutación , Cadenas Pesadas de Miosina/metabolismo , Fenotipo , Adulto JovenRESUMEN
AIMS: Retinoic acid-related orphan receptor γ (RORγ), a master regulator of T-helper 17 (Th17) cell function and differentiation, is an attractive target for treatment of Th17-driven diseases. This first-in-human study aimed to investigate the pharmacokinetics, pharmacodynamics, safety and tolerability of the inverse RORγ agonist AZD0284. METHODS: We conducted a phase I, randomized, single-blind, placebo-controlled, two-part, first-in-human study with healthy subjects receiving single (4-238 mg) or multiple (12-100 mg) oral doses of AZD0284 or placebo after overnight fasting. Subjects in the one single dose cohort additionally received a single dose of AZD0284 after a high-calorie meal. AZD0284 plasma concentrations, as well as inhibition of ex vivo-stimulated interleukin (IL)-17A release in whole blood, were frequently measured after both single and multiple dosing. RESULTS: Eighty-three men participated in the study. AZD0284 was absorbed rapidly into plasma after oral dosing and exhibited a terminal half-life of 13-16 hours. Both the area under the concentration-time curve (AUC) and maximum concentration (Cmax ) increased subproportionally with increasing dose (95% confidence intervals of slope parameter were 0.71-0.84 and 0.72-0.88 for AUC and Cmax , respectively). Food intake delayed the absorption of AZD0284 but did not affect the overall exposure or half-life. AZD0284 showed dose-dependent reduction of ex vivo-stimulated IL-17A release after both single and multiple doses. No significant safety concerns were identified in the study. CONCLUSIONS: AZD0284 was well tolerated, rapidly and dose-dependently absorbed, and reduced stimulated IL-17A release after single and multiple dosing. The results of this study support further clinical development of AZD0284.
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Tretinoina , Administración Oral , Área Bajo la Curva , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Semivida , Humanos , Masculino , Método Simple CiegoRESUMEN
Artificial neural networks are machine-learning algorithms designed to analyse data without a pre-existing hypothesis as to any associations that may exist. This technique has not previously been applied to the risk stratification of patients referred with suspected deep vein thrombosis (DVT). Current assessment is usually with a points-based clinical score, which may be combined with a D-dimer blood test. A neural network was trained to risk-stratify patients presenting with suspected DVT and its performance compared with existing tools. Data from 11 490 cases of suspected DVT presenting consecutively between 1 January 2011 and 31 December 2017 were analysed, and 7080 for whom all components of the Wells' score, a D-dimer and an ultrasound result were available were included in the analysis. The data were broken into a training set of 5270 patients, used to develop the algorithm, and a testing set of 1810 patients to assess performance of the trained algorithm. This network was able to exclude DVT without the need for ultrasound in significantly more patients than existing risk assessment scores, whilst retaining very low false negatives rates. More generally, this approach may improve the analysis of complex data to support decision-making in other areas of clinical medicine.
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Redes Neurales de la Computación , Trombosis de la Vena/diagnóstico , Adulto , Algoritmos , Biomarcadores/sangre , Reacciones Falso Negativas , Femenino , Productos de Degradación de Fibrina-Fibrinógeno/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Prueba de Estudio Conceptual , Estudios Retrospectivos , Medición de Riesgo/métodos , UltrasonografíaRESUMEN
AZD8848 is a TLR7 agonist antedrug developed for administration by inhalation dosing for the treatment of allergic diseases, such as asthma. Allergic asthma is associated with increased levels of Th2 cytokines which are suppressed for extended periods by TLR7 agonists in a number of preclinical models of allergic airway inflammation. However, TLRs form a central part of innate immunity and their activation often results in proinflammatory responses. Whilst AZD8848's antedrug mechanism is designed to restrict its pharmacological action beyond the lung, the effect of chronic, supramaximal dosing to the target tissue has yet to be defined. To support clinical development of this potentially disease modifying approach the nonclinical safety and pharmacodynamics of AZD8848 were evaluated in cynomolgus monkeys in studies examining single or multiple weekly inhaled doses. Here we show that following a single dose nearly all responses returned to baseline within a week. During multiple dosing serum biomarkers were quantified over the dosing period and indicated a limited systemic response. The dose at which maximal interferon responses were seen was dependent on dose. Thorough histopathological examination revealed a dose related increase of size and cells of lymphoid tissues in the lung and nose. Local lymphoid responses were recovered after the treatment free period. These studies are the first to evaluate safety of an inhaled TLR7 agonist and demonstrate AZD8848 is safe with a no observed adverse effect level at 26µg/kg allowing progression to man with weekly inhalation dosing.
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Adenosina/análogos & derivados , Citocinas/sangre , Tejido Linfoide/efectos de los fármacos , Fenilacetatos/toxicidad , Receptor Toll-Like 7/agonistas , Adenosina/administración & dosificación , Adenosina/farmacocinética , Adenosina/toxicidad , Administración por Inhalación , Animales , Citocinas/genética , Femenino , Tejido Linfoide/inmunología , Macaca fascicularis , Masculino , Fenilacetatos/administración & dosificación , Fenilacetatos/farmacocinéticaRESUMEN
The story of the discovery of aspirin stretches back more than 3500 years to when bark from the willow tree was used as a pain reliever and antipyretic. It involves an Oxfordshire clergyman, scientists at a German dye manufacturer, a Nobel Prize-winning discovery and a series of pivotal clinical trials. Aspirin is now the most commonly used drug in the world. Its role in preventing cardiovascular and cerebrovascular disease has been revolutionary and one of the biggest pharmaceutical success stories of the last century.
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Antiinflamatorios no Esteroideos/uso terapéutico , Antipiréticos/uso terapéutico , Aspirina/uso terapéutico , Inhibidores de Agregación Plaquetaria/uso terapéutico , Salix , Antiinflamatorios no Esteroideos/historia , Antiinflamatorios no Esteroideos/farmacología , Antipiréticos/historia , Antipiréticos/farmacología , Aspirina/historia , Aspirina/farmacología , Enfermedades Cardiovasculares/historia , Enfermedades Cardiovasculares/prevención & control , Descubrimiento de Drogas/historia , Predicción , Enfermedades Hematológicas/historia , Enfermedades Hematológicas/prevención & control , Hemorragia/inducido químicamente , Hemorragia/historia , Historia del Siglo XVIII , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Historia Antigua , Corteza de la Planta , Inhibidores de Agregación Plaquetaria/historia , Inhibidores de Agregación Plaquetaria/farmacologíaRESUMEN
BACKGROUND: Pulmonary embolism (PE) can occur when a thrombus (blood clot) travels through the veins and lodges in the arteries of the lungs, producing an obstruction. People who are thought to be at risk include those with cancer, people who have had a recent surgical procedure or have experienced long periods of immobilisation and women who are pregnant. The clinical presentation can vary, but unexplained respiratory symptoms such as difficulty breathing, chest pain and an increased respiratory rate are common.D-dimers are fragments of protein released into the circulation when a blood clot breaks down as a result of normal body processes or with use of prescribed fibrinolytic medication. The D-dimer test is a laboratory assay currently used to rule out the presence of high D-dimer plasma levels and, by association, venous thromboembolism (VTE). D-dimer tests are rapid, simple and inexpensive and can prevent the high costs associated with expensive diagnostic tests. OBJECTIVES: To investigate the ability of the D-dimer test to rule out a diagnosis of acute PE in patients treated in hospital outpatient and accident and emergency (A&E) settings who have had a pre-test probability (PTP) of PE determined according to a clinical prediction rule (CPR), by estimating the accuracy of the test according to estimates of sensitivity and specificity. The review focuses on those patients who are not already established on anticoagulation at the time of study recruitment. SEARCH METHODS: We searched 13 databases from conception until December 2013. We cross-checked the reference lists of relevant studies. SELECTION CRITERIA: Two review authors independently applied exclusion criteria to full papers and resolved disagreements by discussion.We included cross-sectional studies of D-dimer in which ventilation/perfusion (V/Q) scintigraphy, computerised tomography pulmonary angiography (CTPA), selective pulmonary angiography and magnetic resonance pulmonary angiography (MRPA) were used as the reference standard.⢠PARTICIPANTS: Adults who were managed in hospital outpatient and A&E settings and were suspected of acute PE were eligible for inclusion in the review if they had received a pre-test probability score based on a CPR.⢠INDEX TESTS: quantitative, semi quantitative and qualitative D-dimer tests.⢠Target condition: acute symptomatic PE.⢠Reference standards: We included studies that used pulmonary angiography, V/Q scintigraphy, CTPA and MRPA as reference standard tests. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed quality using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). We resolved disagreements by discussion. Review authors extracted patient-level data when available to populate 2 × 2 contingency tables (true-positives (TPs), true-negatives (TNs), false-positives (FPs) and false-negatives (FNs)). MAIN RESULTS: We included four studies in the review (n = 1585 patients). None of the studies were at high risk of bias in any of the QUADAS-2 domains, but some uncertainty surrounded the validity of studies in some domains for which the risk of bias was uncertain. D-dimer assays demonstrated high sensitivity in all four studies, but with high levels of false-positive results, especially among those over the age of 65 years. Estimates of sensitivity ranged from 80% to 100%, and estimates of specificity from 23% to 63%. AUTHORS' CONCLUSIONS: A negative D-dimer test is valuable in ruling out PE in patients who present to the A&E setting with a low PTP. Evidence from one study suggests that this test may have less utility in older populations, but no empirical evidence was available to support an increase in the diagnostic threshold of interpretation of D-dimer results for those over the age of 65 years.
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Productos de Degradación de Fibrina-Fibrinógeno/análisis , Embolia Pulmonar/diagnóstico , Enfermedad Aguda , Adulto , Biomarcadores/sangre , Estudios Transversales , Reacciones Falso Negativas , Reacciones Falso Positivas , Humanos , Embolia Pulmonar/sangre , Estándares de Referencia , Tromboembolia Venosa/sangre , Tromboembolia Venosa/diagnósticoRESUMEN
The guideline was drafted by a writing group identified by the Haemostasis and Thrombosis Task Force of the British Committee for Standards in Haematology (BCSH). All the authors are consultants in haematology in the UK. A search was performed of PubMed and Embase using the term 'cancer' combined with 'thrombosis', 'treatment', 'prophylaxis' and 'clinical presentation'. The search covered articles published up until December 2014. Only human studies were included and articles not written in English were excluded. References in recent reviews were also examined. The writing group produced the draft guideline, which was subsequently revised by consensus by members of the Haemostasis and Thrombosis Task Force of the BCSH and the BCSH executive. The guideline was then reviewed by the sounding board of the British Society for Haematology (BSH). This comprises 50 or more members of the BSH who have reviewed the guidance and commented on the content and application to the UK setting. The 'GRADE' system was used to quote levels and grades of evidence, details of which can be found at: http://www.bcshguidelines.com/BCSH_PROCESS/EVIDENCE_LEVELS_AND_GRADES_OF_RECOMMENDATION/43_GRADE.html. The objective of this guideline is to provide healthcare professionals with clear guidance on the prevention and management of venous thromboembolism (VTE) in patients with cancer and to advise on an approach to screening for cancer in patients with unprovoked VTE in whom cancer was not initially suspected based on clinical grounds.
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Neoplasias , Tromboembolia Venosa , Trombosis de la Vena , Humanos , Neoplasias/diagnóstico , Neoplasias/terapia , PubMed , Reino Unido , Tromboembolia Venosa/diagnóstico , Tromboembolia Venosa/etiología , Tromboembolia Venosa/terapia , Trombosis de la Vena/diagnóstico , Trombosis de la Vena/etiología , Trombosis de la Vena/terapiaRESUMEN
BACKGROUND: Home-based robotic technologies may offer the possibility of self-directed upper limb exercise after stroke as a means of increasing the intensity of rehabilitation treatment. The current literature has a paucity of robotic devices that have been tested in a home environment. The aim of this research project was to evaluate a robotic device Home-based Computer Assisted Arm Rehabilitation (hCAAR) that can be used independently at home by stroke survivors with upper limb weakness. METHODS: hCAAR device comprises of a joystick handle moved by the weak upper limb to perform tasks on the computer screen. The device provides assistance to the movements depending on users ability. Nineteen participants (stroke survivors with upper limb weakness) were recruited. Outcome measures performed at baseline (A0), at end of 8-weeks of hCAAR use (A1) and 1 month after end of hCAAR use (A2) were: Optotrak kinematic variables, Fugl Meyer Upper Extremity motor subscale (FM-UE), Action Research Arm Test (ARAT), Medical Research Council (MRC) and Modified Ashworth Scale (MAS), Chedoke Arm and Hand Activity Inventory (CAHAI) and ABILHAND. RESULTS: Two participants were unable to use hCAAR: one due to severe paresis and the other due to personal problems. The remaining 17 participants were able to use the device independently in their home setting. No serious adverse events were reported. The median usage time was 433 minutes (IQR 250 - 791 min). A statistically significant improvement was observed in the kinematic and clinical outcomes at A1. The median gain in the scores at A1 were by: movement time 19%, path length 15% and jerk 19%, FM-UE 1 point, total MAS 1.5 point, total MRC 2 points, ARAT 3 points, CAHAI 5.5 points and ABILHAND 3 points. Three participants showed clinically significant improvement in all the clinical outcomes. CONCLUSIONS: The hCAAR feasibility study is the first clinical study of its kind reported in the current literature; in this study, 17 participants used the robotic device independently for eight weeks in their own homes with minimal supervision from healthcare professionals. Statistically significant improvements were observed in the kinematic and clinical outcomes in the study.
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Terapia por Ejercicio/métodos , Rehabilitación/instrumentación , Robótica/métodos , Rehabilitación de Accidente Cerebrovascular , Extremidad Superior/fisiopatología , Actividades Cotidianas , Anciano , Brazo , Computadores , Estudios de Factibilidad , Femenino , Humanos , Masculino , Paresia/rehabilitación , Resultado del TratamientoRESUMEN
Dabigatran is an oral direct thrombin inhibitor (DTI) licensed for stroke prevention in atrial fibrillation and likely to be soon approved in Europe for treatment of venous thrombosis. Predictable pharmacokinetics and a reduced risk of intracranial haemorrhage do not negate the potential risk of haemorrhage. Unlike warfarin, there is no reversal agent and measurement of the anticoagulant effect is not 'routine'. The prothrombin time/international normalised ratio response to dabigatran is inconsistent and should not be measured when assessing a patient who is bleeding or needs emergency surgery. The activated partial thromboplastin time (APTT) provides a qualitative measurement of the anticoagulant effect of dabigatran. Knowledge of the time of last dose is important for interpretation of the APTT. Commercially available DTI assays provide a quantitative measurement of active dabigatran concentration in the plasma. If a patient receiving dabigatran presents with bleeding: omit/delay next dose of dabigatran; measure APTT and thrombin time (consider DTI assay if available); administer activated charcoal, with sorbitol, if within 2 h of dabigatran ingestion; give tranexamic acid (1 g intravenously if significant bleeding); maintain renal perfusion and urine output to aid dabigatran excretion. Dabigatran exhibits low protein binding and may be removed by dialysis. Supportive care should form the mainstay of treatment. If bleeding is life/limb threatening, consider an additional haemostatic agent. There is currently no evidence to support the choice of one haemostatic agent (FEIBA, recombinant factor VIIa, prothrombin complex concentrates) over another. Choice will depend on access to and experience with available haemostatic agent(s).
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Antitrombinas/efectos adversos , Bencimidazoles/efectos adversos , Sobredosis de Droga/terapia , Hemorragia/inducido químicamente , beta-Alanina/análogos & derivados , Pruebas de Coagulación Sanguínea , Dabigatrán , Manejo de la Enfermedad , Servicio de Urgencia en Hospital , Hemorragia/terapia , Humanos , Hemorragia Posoperatoria/inducido químicamente , Hemorragia Posoperatoria/terapia , beta-Alanina/efectos adversosRESUMEN
Wear simulation aims to assess wear rates and their dependence on factors like load, kinematics, temperature, and implant orientation. Despite its significance, there is a notable gap in research concerning advancements in simulator control systems and the testing of clinically relevant waveforms. This study addresses this gap by focusing on enhancing the conventional proportional-integral-derivative (PID) controller used in joint simulators through the development of a fuzzy logic-based controller. Leveraging a single-input multiple-output (SIMO) fuzzy logic control system, this study aimed to improve displacement control, augmenting the traditional proportional-integral (PI) tuning approach. The implementation and evaluation of a novel Fuzzy-PI control algorithm were conducted on the Leeds spine wear simulator. This study also included the testing of dailyliving (DL) profiles, particularly from the hip joint, to broaden the scope of simulation scenarios. While both the conventional PI controller and the Fuzzy-PI controller met ISO tolerance criteria for the spine flexion-extension (FE) profile at 1 Hz, the Fuzzy-PI controller demonstrated superior performance at higher frequencies and with DL profiles due to its real-time adaptive tuning capability. The Fuzzy-PI controller represents a significant advancement in joint wear simulation, offering improved control functionalities and more accurate emulation of real-world physiological dynamics.
RESUMEN
Despite the availability of comprehensive evidence-based guidelines there are difficult and controversial areas in the management of venous thromboembolism. Institutions and even countries disagree on the importance of calf vein thrombosis, with some rigorously detecting and treating it and others deliberately not looking for it. The need to treat proximal deep vein thrombosis and pulmonary embolism is accepted but which patients with an unprovoked first event should have long-term anticoagulation has become a difficult clinical decision. We are uncertain how to reduce the incidence of post-thrombotic syndrome seen in a substantial number of patients. How hard to look for an undiagnosed underlying cancer has become a contentious issue particularly in the United Kingdom following the recent publication of a guideline from the National Institute for Health and Clinical Excellence. Whilst we are wrestling with these dilemmas we are entering an era of new anticoagulants and have to solve the logistical problems of introducing them into clinical practice despite cost pressures. These issues will be explored in this review.
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Tromboembolia Venosa/diagnóstico , Tromboembolia Venosa/terapia , Animales , Anticoagulantes/administración & dosificación , Anticoagulantes/efectos adversos , Anticoagulantes/uso terapéutico , Bovinos , Detección Precoz del Cáncer , Factor Xa/administración & dosificación , Factor Xa/uso terapéutico , Humanos , Neoplasias/complicaciones , Neoplasias/diagnóstico , Factores de Tiempo , Tromboembolia Venosa/complicacionesAsunto(s)
Anticuerpos Monoclonales Humanizados/uso terapéutico , Anticoagulantes/uso terapéutico , Antitrombinas/efectos adversos , Dabigatrán/efectos adversos , Dabigatrán/antagonistas & inhibidores , Sobredosis de Droga/tratamiento farmacológico , Adolescente , Anticuerpos Monoclonales Humanizados/farmacología , Anticoagulantes/farmacología , Antitrombinas/administración & dosificación , Coagulación Sanguínea/efectos de los fármacos , Pruebas de Coagulación Sanguínea , Dabigatrán/administración & dosificación , Sobredosis de Droga/sangre , Sobredosis de Droga/diagnóstico , Femenino , HumanosAsunto(s)
Familia , Hemofilia A/diagnóstico , Hemofilia B/diagnóstico , Alelos , Sustitución de Aminoácidos , Factor IX/genética , Factor VIII/genética , Femenino , Genotipo , Hemofilia A/sangre , Hemofilia A/genética , Hemofilia B/sangre , Hemofilia B/genética , Humanos , Masculino , Mutación , Linaje , Diagnóstico PrenatalRESUMEN
BACKGROUND: Warfarin is used as an oral anticoagulant. However, there is wide variation in patient response to warfarin dose. This variation, as well as the necessity of keeping within a narrow therapeutic range, means that selection of the correct warfarin dose at the outset of treatment is not straightforward. OBJECTIVES: To assess the effectiveness of different initiation doses of warfarin in terms of time in-range, time to INR in-range and effect on serious adverse events. SEARCH METHODS: We searched CENTRAL, DARE and the NHS Health economics database on The Cochrane Library (2012, Issue 4); MEDLINE (1950 to April 2012) and EMBASE (1974 to April 2012). SELECTION CRITERIA: All randomised controlled trials which compared different initiation regimens of warfarin. DATA COLLECTION AND ANALYSIS: Review authors independently assessed studies for inclusion. Authors also assessed the risk of bias and extracted data from the included studies. MAIN RESULTS: We identified 12 studies of patients commencing warfarin for inclusion in the review. The overall risk of bias was found to be variable, with most studies reporting adequate methods for randomisation but only two studies reporting adequate data on allocation concealment. Four studies (355 patients) compared 5 mg versus 10 mg loading doses. All four studies reported INR in-range by day five. Although there was notable heterogeneity, pooling of these four studies showed no overall difference between 5 mg versus 10 mg loading doses (RR 1.17, 95% CI 0.77 to 1.77, P = 0.46, I(2) = 83%). Two of these studies used two consecutive INRs in-range as the outcome and showed no difference between a 5 mg and 10 mg dose by day five (RR 0.86, 95% CI 0.62 to 1.19, P = 0.37, I(2 )= 22%); two other studies used a single INR in-range as the outcome and showed a benefit for the 10 mg initiation dose by day 5 (RR 1.49, 95% CI 1.01 to 2.21, P = 0.05, I(2 )= 72%). Two studies compared a 5 mg dose to other doses: a 2.5 mg initiation dose took longer to achieve the therapeutic range (2.7 versus 2.0 days; P < 0.0001), but those receiving a calculated initiation dose achieved a target range quicker (4.2 days versus 5 days, P = 0.007). Two studies compared age adjusted doses to 10 mg initiation doses. More elderly patients receiving an age adjusted dose achieved a stable INR compared to those receiving a 10 mg initial dose (and Fennerty regimen). Four studies used genotype guided dosing in one arm of each trial. Three studies reported no overall differences; the fourth study, which reported that the genotype group spent significantly more time in-range (P < 0.001), had a control group whose INRs were significantly lower than expected. No clear impacts from adverse events were found in either arm to make an overall conclusion. AUTHORS' CONCLUSIONS: The studies in this review compared loading doses in several different situations. There is still considerable uncertainty between the use of a 5 mg and a 10 mg loading dose for the initiation of warfarin. In the elderly, there is some evidence that lower initiation doses or age adjusted doses are more appropriate, leading to fewer high INRs. However, there is insufficient evidence to warrant genotype guided initiation.