210 research outputs found

    [Accepted Manuscript] Comparison of Propensity Score Methods and Covariate Adjustment: Evaluation in 4 Cardiovascular Studies.

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    Propensity scores (PS) are an increasingly popular method to adjust for confounding in observational studies. Propensity score methods have theoretical advantages over conventional covariate adjustment, but their relative performance in real-word scenarios is poorly characterized. We used datasets from 4 large-scale cardiovascular observational studies (PROMETHEUS, ADAPT-DES [the Assessment of Dual AntiPlatelet Therapy with Drug-Eluting Stents], THIN [The Health Improvement Network], and CHARM [Candesartan in Heart Failure-Assessment of Reduction in Mortality and Morbidity]) to compare the performance of conventional covariate adjustment with 4 common PS methods: matching, stratification, inverse probability weighting, and use of PS as a covariate. We found that stratification performed poorly with few outcome events, and inverse probability weighting gave imprecise estimates of treatment effect and undue influence to a small number of observations when substantial confounding was present. Covariate adjustment and matching performed well in all of our examples, although matching tended to give less precise estimates in some cases. PS methods are not necessarily superior to conventional covariate adjustment, and care should be taken to select the most suitable method

    [Accepted Manuscript] Left Main Revascularization With PCI or CABG in Patients With Chronic Kidney Disease: EXCEL Trial.

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    The optimal revascularization strategy for patients with left main coronary artery disease (LMCAD) and chronic kidney disease (CKD) remains unclear. This study investigated the comparative effectiveness of percutaneous coronary intervention (PCI) versus coronary artery bypass graft (CABG) surgery in patients with LMCAD and low or intermediate anatomical complexity according to baseline renal function from the multicenter randomized EXCEL (Evaluation of XIENCE Versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization) trial. CKD was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m2 using the CKD Epidemiology Collaboration equation. Acute renal failure (ARF) was defined as a serum creatinine increase ≥5.0 mg/dl from baseline or a new requirement for dialysis. The primary composite endpoint was the composite of death, myocardial infarction (MI), or stroke at 3-year follow-up. CKD was present in 361 of 1,869 randomized patients (19.3%) in whom baseline estimated glomerular filtration rate was available. Patients with CKD had higher 3-year rates of the primary endpoint compared with those without CKD (20.8% vs. 13.5%; hazard ratio [HR]: 1.60; 95% confidence interval [CI]: 1.22 to 2.09; p = 0.0005). ARF within 30 days occurred more commonly in patients with compared with those without CKD (5.0% vs. 0.8%; p < 0.0001), and was strongly associated with the 3-year risk of death, stroke, or MI (50.7% vs. 14.4%; HR: 4.59; 95% CI: 2.73 to 7.73; p < 0.0001). ARF occurred less commonly after revascularization with PCI compared with CABG both in patients with CKD (2.3% vs. 7.7%; HR: 0.28; 95% CI: 0.09 to 0.87) and in those without CKD (0.3% vs. 1.3%; HR: 0.20; 95% CI: 0.04 to 0.90; pinteraction = 0.71). There were no significant differences in the rates of the primary composite endpoint after PCI and CABG in patients with CKD (23.4% vs. 18.1%; HR: 1.25; 95% CI: 0.79 to 1.98) and without CKD (13.4% vs. 13.5%; HR: 0.97; 95% CI: 0.73 to 1.27; pinteraction = 0.38). Patients with CKD undergoing revascularization for LMCAD in the EXCEL trial had increased rates of ARF and reduced event-free survival. ARF occurred less frequently after PCI compared with CABG. There were no significant differences between PCI and CABG in terms of death, stroke, or MI at 3 years in patients with and without CKD. (EXCEL Clinical Trial [EXCEL]; NCT01205776)

    Prepositions, syntax and the acquisition of English as a foreign language

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    SIGLEAvailable from British Library Document Supply Centre-DSC:DXN017761 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Current and future challenges in the design and analysis of cluster randomization trials

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    Randomized trials in which the unit of randomization is a community, worksite, school or family are becoming widely used in the evaluation of life-style interventions for the prevention of disease. The increasing interest in adopting a cluster randomization design is being matched by rapid methodological developments. In this paper we describe several of these developments. Brief mention is also made of issues related to economic analysis and to the planning and conduct of meta-analyses for cluster randomization trials. Recommendations for reporting are also discussed. Copyright © 2001 John Wiley & Sons, Ltd

    Evaluating clinical trials

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