Methods for specifying the target difference in a randomised controlled trial : the Difference ELicitation in TriAls (DELTA) systematic review

Peer reviewedPublisher PD

The benefits and risks of bacille Calmette-Guérin vaccination among infants at high risk for both tuberculosis and severe combined immunodeficiency: assessment by Markov model

BACKGROUND: Bacille Calmette-Guérin (BCG) vaccine is given to Canadian Aboriginal neonates in selected communities. Severe reactions and deaths associated with BCG have been reported among infants born with immunodeficiency syndromes. The main objective of this study was to estimate threshold values for severe combined immunodeficiency (SCID) incidence, above which BCG is associated with greater risk than benefit. METHODS: A Markov model was developed to simulate the natural histories of tuberculosis (TB) and SCID in children from birth to 14 years. The annual risk of tuberculous infection (ARI) and SCID incidence were varied in analyses. The model compared a scenario of no vaccination to intervention with BCG. Appropriate variability and uncertainty analyses were conducted. Outcomes included TB incidence and quality-adjusted life years (QALYs). RESULTS: In sensitivity analyses, QALYs were lower among vaccinated infants if the ARI was 0.1% and the rate of SCID was higher than 4.2 per 100,000. Assuming an ARI of 1%, this threshold increased to 41 per 100,000. In uncertainty analyses (Monte Carlo simulations) which assumed an ARI of 0.1%, QALYs were not significantly increased by BCG unless SCID incidence is 0. With this ARI, QALYs were significantly decreased among vaccinated children if SCID incidence exceeds 23 per 100,000. BCG is associated with a significant increase in QALYs if the ARI is 1%, and SCID incidence is below 5 per 100,000. CONCLUSION: The possibility that Canadian Aboriginal children are at increased risk for SCID has serious implications for continued BCG use in this population. In this context, enhanced TB Control – including early detection and treatment of infection – may be a safer, more effective alternative

What's behind the white coat: Potential mechanisms of physician-attributable variation in critical care.

BackgroundCritical care intensity is known to vary across regions and centers, yet the mechanisms remain unidentified. Physician behaviors have been implicated in the variability of intensive care near the end of life, but physician characteristics that may underlie this association have not been determined.PurposeWe sought to identify behavioral attributes that vary among intensivists to generate hypotheses for mechanisms of intensivist-attributable variation in critical care delivery.MethodsWe administered a questionnaire to intensivists who participated in a prior cohort study in which intensivists made prognostic estimates. We evaluated the degree to which scores on six attribute measures varied across intensivists. Measures were selected for their relevance to preference-sensitive critical care: a modified End-of-Life Preferences (EOLP) scale, Life Orientation Test-Revised (LOT-R), Jefferson Scale of Empathy (JSE), Physicians' Reactions to Uncertainty (PRU) scale, Collett-Lester Fear of Death (CLFOD) scale, and a test of omission bias. We conducted regression analyses assessing relationships between intensivists' attribute scores and their prognostic accuracy, as physicians' prognostic accuracy may influence preference-sensitive decisions.Results20 of 25 eligible intensivists (80%) completed the questionnaire. Intensivists' scores on the EOLP, LOT-R, PRU, CLFOD, and omission bias measures varied considerably, while their responses on the JSE scale did not. There were no consistent associations between attribute scores and prognostic accuracy.ConclusionsIntensivists vary in feasibly measurable attributes relevant to preference-sensitive critical care delivery. These attributes represent candidates for future research aimed at identifying mechanisms of clinician-attributable variation in critical care and developing effective interventions to reduce undue variation

Clinical Interventions to Prevent Tumour Lysis Syndrome in Hematologic Malignancy: A Multisite Retrospective Chart Review

ABSTRACTBackground: Tumour lysis syndrome (TLS) occurs when lysis of malignant cells causes electrolyte disturbances and potentially organ dysfunction. Guidelines recommending preventive therapy according to TLS risk are based on low-quality evidence.Objectives: The primary objective was to characterize utilization of TLS preventive strategies through comprehensive description of current practice. Secondary objectives were to determine TLS incidence, to compare use of preventive strategies among intermediate- and high-risk patients, and to describe TLS treatment strategies.Methods: This retrospective chart review examined data for patients with newly diagnosed hematologic malignancy who were admitted to an oncology centre and/or affiliated intensive care unit between October 2015 and September 2016 in Toronto, Ontario, Canada. Results: Fifty-eight patients (29 at intermediate risk, 29 at high risk) were eligible for inclusion. Use of preventive allopurinol, IV bicarbonate, and furosemide was similar between groups. Rasburicase was more frequently used for high-risk patients (3% [1/29] of intermediate-risk patients versus 36% [9/25] of high-risk patients; p = 0.003). In 4 (14%) of the intermediate-risk patients and 2 (8%) of the high-risk patients, TLS developed during the admission. TLS was observed in 10% (1/10) of patients who received preventive rasburicase and 11% (5/44) of those who did not (p > 0.99), and in 9% (4/45) of patients who received preventive IV bicarbonate and 25% (2/8) of those who did not (p = 0.22). Treatment strategies included rasburicase, IV bicarbonate, furosemide, and renal replacement therapy.Conclusions: In this retrospective chart review, rasburicase was more commonly used for high-risk patients, whereas the use of other agents was similar between risk groups. This pattern of use is inconsistent with guidelines, which recommend that all high-risk patients receive rasburicase. There was no difference in TLS incidence between patients who did and did not receive preventive rasburicase or IV bicarbonate. Further prospective studies are needed to inform management of patients with malignancies who are at intermediate or high risk of TLS.RÉSUMÉContexte : Le syndrome de lyse tumorale (SLT) se produit lorsque la lyse de cellules malignes provoque des perturbations électrolytiques et la dysfonction potentielle d’un organe. Les lignes directrices préconisant une thérapie préventive basée sur le risque de SLT se fondent sur des éléments de preuve de piètre qualité.Objectifs : L’objectif principal consistait à décrire l’adoption des stratégies de prévention du SLT en décrivant précisément la pratique actuelle. Les objectifs secondaires consistaient, quant à eux, à déterminer l’incidence du SLT, à comparer l’utilisation des stratégies de prévention pour les patients présentant un risque élevé et moyen et à décrire les stratégies de traitement du SLT.Méthodes : Cet examen rétrospectif a permis d’examiner les données de patients ayant récemment reçu un diagnostic d’hémopathie maligne et ayant été admis dans un centre d’oncologie ou une unité de soins intensifs affiliée, entre octobre 2015 et septembre 2016 à Toronto (Ontario), au Canada.Résultats : Cinquante-huit patients (29 présentant un risque moyen et 29 un risque élevé) étaient admissibles. L’utilisation d’allopurinol à titre préventif, de bicarbonate par voie intraveineuse et de furosémide était similaire d’un groupe à l’autre. Le rasburicase était plus fréquemment utilisé pour les patients présentant un risque élevé (3 % [1/29] de patients présentant un risque moyen contre 36 % [9/25] de patients présentant un risque élevé; p = 0.003). Quatre (14 %) patients présentant un risque moyen et deux (8 %) présentant un risque élevé ont développé un SLT pendant l’admission. Le SLT a été observé chez 10 % (1/10) des patients ayant reçu du rasburicase à titre préventif et chez 11 % (5/44) des patients qui n’en avaient pas reçu (p > 0,99); il a aussi été observé chez 9 % (4/45) des patients ayant reçu du bicarbonate par voie intraveineuse à titre préventif et chez 25 % (2/8) des patients qui n’en avaient pas reçu (p = 0.22). Les stratégies de traitement comprenaient le rasburicase, le bicarbonate par voie intraveineuse, le furosémide et la thérapie de remplacement rénal.Conclusions : Dans cet examen rétrospectif des dossiers, l’usage du rasburicase était plus fréquent pour les patients présentant un risque élevé, tandis que celui d’autres agents était similaire entre les groupes à risque. Ce schéma d’utilisation n’est pas conforme aux lignes directrices, qui recommandent que tous les patients présentant un risque élevé reçoivent du rasburicase. Aucune différence n’est apparue dans l’incidence du SLT parmi les patients ayant reçu du rasburicase ou du bicarbonate par voie intraveineuse à titre préventif et parmi ceux qui n’en avaient pas reçu. Davantage d’études prospectives sont nécessaires pour mieux connaitre la gestion des patients à haut risque ou ceux qui présentent des risques moyens de SLT, mais qui ont des malignités.