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Sainfort F.,University of Minnesota | Kuntz K.M.,University of Minnesota | Gregory S.,University of Minnesota | Butler M.,University of Minnesota | And 4 more authors.
Value in Health | Year: 2013

Objective: Decision models are sometimes used alongside systematic reviews to synthesize evidence. Clarity, however, is lacking about when and how to conduct modeling studies in tandem with systematic reviews, as well as about how to evaluate and present model results. The objective of this study was to collect and analyze information from various sources to inform the development of a framework for deciding when and how a decision model should be added to a systematic review. Methods: We collected data through 1) review and analysis of evidence reports that used decision models; 2) review and synthesis of current best practices for the development of decision models; 3) interviews of Evidence-Based Practice Center directors and selected staff, United States Preventive Services Task Force members, and decision modelers who developed models used by the United States Preventive Services Task Force; and 4) a focus group of expert modelers. Results: Models are well suited to address gaps in the literature, better suited for certain types of research questions, and essential for determining the value of information relating to future research. Opinions differ regarding whether model outputs constitute evidence, but interviewees expressed concern over the lack of standards and directions in grading and reporting such evidence. Interviews of stakeholders and modelers revealed the importance of communication and presentation of model results as well as the importance of model literacy and involvement of stakeholders. Conclusions: The study demonstrates the need for a framework for deciding when and how to use models alongside systematic reviews and provides information to develop such a framework. © 2013 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. Source


Thomas R.J.,Beth Israel Deaconess Medical Center | Mietus J.E.,Beth Israel Deaconess Medical Center | Peng C.-K.,Beth Israel Deaconess Medical Center | Guo D.,Sleep Disorders Center | And 6 more authors.
Sleep Medicine | Year: 2014

Objectives: The physiologic relationship between slow-wave activity (SWA) (0-4. Hz) on the electroencephalogram (EEG) and high-frequency (0.1-0.4. Hz) cardiopulmonary coupling (CPC) derived from electrocardiogram (ECG) sleep spectrograms is not known. Because high-frequency CPC appears to be a biomarker of stable sleep, we tested the hypothesis that that slow-wave EEG power would show a relatively fixed-time relationship to periods of high-frequency CPC. Furthermore, we speculated that this correlation would be independent of conventional nonrapid eye movement (NREM) sleep stages. Methods: We analyzed selected datasets from an archived polysomnography (PSG) database, the Sleep Heart Health Study I (SHHS-I). We employed the cross-correlation technique to measure the degree of which 2 signals are correlated as a function of a time lag between them. Correlation analyses between high-frequency CPC and delta power (computed both as absolute and normalized values) from 3150 subjects with an apnea-hypopnea index (AHI) of ≤5 events per hour of sleep were performed. Results: The overall correlation (r) between delta power and high-frequency coupling (HFC) power was 0.40 ± 0.18 (P = .001). Normalized delta power provided improved correlation relative to absolute delta power. Correlations were somewhat reduced in the second half relative to the first half of the night (r= 0.45. ± 0.20 vs r= 0.34. ± 0.23). Correlations were only affected by age in the eighth decade. There were no sex differences and only small racial or ethnic differences were noted. Conclusions: These results support a tight temporal relationship between slow wave power, both within and outside conventional slow wave sleep periods, and high frequency cardiopulmonary coupling, an ECG-derived biomarker of "stable" sleep. These findings raise mechanistic questions regarding the cross-system integration of neural and cardiopulmonary control during sleep. © 2013 Elsevier B.V. Source


Lal B.K.,University of Maryland Baltimore County | Zhou W.,Stanford University | Li Z.,Yale University | Li Z.,Veterans Affairs Cooperative Studies Program Coordinating Center | And 4 more authors.
Journal of Vascular Surgery | Year: 2015

Objective The Veterans Affairs Open Versus Endovascular Repair (OVER) Trial of Abdominal Aortic Aneurysms study was a randomized controlled trial comparing open vs endovascular repair (EVAR) in standard-risk patients with infrarenal aortic aneurysms. The analysis reported here identifies characteristics, risk factors, and long-term outcome of endoleaks in patients treated with EVAR in the OVER cohort. Methods The OVER trial enrolled 881 patients, of whom 439 received successful EVAR. Logistic regression analysis was used to identify predictors for endoleaks and secondary interventions. Kaplan-Meier survival analysis, longitudinal plots, and generalized linear mixed models methods were used to describe time to endoleak detection, resolution, or death. Results During a mean follow-up of 6.2 ± 2.4 years, 135 patients (30.5%) developed 187 endoleaks. Four patients with EVAR went on to rupture; these four patients did not all have an endoleak. Mortality between patients who did and did not develop endoleaks was not significantly different. The 187 endoleaks included 12% type I, 76% type II, 3% type III, 3% type IV, and 6% indeterminate. Patient demographics and vascular risk factors were not associated with endoleak development. The presence of endoleaks resulted in an increase in aneurysm diameter over time (P <.0001). Fifty-three percent of endoleaks resolved spontaneously, and 31.9% received secondary interventions. The initial aneurysm size independently predicted a need for secondary interventions (P <.0003). Delayed type II endoleaks (detected >1 year after EVAR) were associated with aneurysm enlargement compared with the early counterpart. There was no difference in aneurysm size or length of survival between type II and other types of endoleak. Conclusions We present one of the most comprehensive and longest follow-up analyses of patients treated with aortic endografts. Endoleaks were common and negatively affected aneurysm diameter reduction. Delayed type II endoleaks were associated with late aneurysm diameter enlargement. Endoleaks and aneurysm diameter enlargement were not associated with excess mortality compared with those without these features. © Published by Elsevier Inc. Source


Adabag S.,Veterans Affairs Health Care System | Adabag S.,University of Minnesota | Rector T.S.,Veterans Affairs Health Care System | Rector T.S.,University of Minnesota | And 8 more authors.
European Journal of Heart Failure | Year: 2014

Aims Sudden cardiac death (SCD) accounts for ∼ 25% of all deaths in heart failure with preserved ejection fraction (HFpEF). However, strategies to identify HFpEF patients at a higher risk of SCD have not been developed.Methods and results We studied 4128 patients with HFpEF enrolled in the Irbesartan in Patients with Heart Failure and Preserved Ejection Fraction (I-PRESERVE) trial. All SCDs were adjudicated by a clinical endpoint committee. Cumulative incidences of SCD were estimated counting other deaths as competing risks. Cox regression analysis was used to generate a risk model for SCD. During a mean follow-up of 4.1 years, 231 (5.6%) patients died suddenly and 650 (15.7%) died non-suddenly. A multivariable model in 3480 patients including age, gender, history of diabetes and myocardial infarction, LBBB on ECG, and the natural logarithm of NT-proBNP identified a subgroup of 837 (24%) patients with ≥10% cumulative incidence of SCD over 5 years, accounting for other deaths as competing risk (Harrell's C index 0.75). The 5-year cumulative incidences of SCD in the higher and lower risk groups were 11% and 4%, respectively. In the higher risk group, 32% of deaths were SCD compared with 26% in the entire I-PRESERVE cohort.Conclusions A multivariable prediction model identified patients with HFpEF who have a ≥10% risk of SCD over 5 years, similar to the risk of SCD in the Sudden Cardiac Death in Heart Failure (SCD-Heft) trial. This model may be useful for selecting patients with HFpEF for SCD prevention trials. © 2014 The Authors European Journal of Heart Failure. Source


Goldman S.,Cardiology Section 1 111C | Goldman S.,University of Arizona | Sethi G.K.,Cardiology Section 1 111C | Sethi G.K.,University of Arizona | And 39 more authors.
JAMA - Journal of the American Medical Association | Year: 2011

Context: Arterial grafts are thought to be better conduits than saphenous vein grafts for coronary artery bypass grafting (CABG) based on experience with using the left internal mammary artery to bypass the left anterior descending coronary artery. The efficacy of the radial artery graft is less clear. Objective: To compare 1-year angiographic patency of radial artery grafts vs saphenous vein grafts in patients undergoing elective CABG. Design, Setting, and Participants: Multicenter, randomized controlled trial conducted from February 2003 to February 2009 at 11 Veterans Affairs medical centers among 757 participants (99% men) undergoing first-time elective CABG. Interventions: The left internal mammary artery was used to preferentially graft the left anterior descending coronary artery whenever possible; the best remaining recipient vessel was randomized to radial artery vs saphenous vein graft. Main Outcome Measures: The primary end point was angiographic graft patency at 1 year after CABG. Secondary end points included angiographic graft patency at 1 week after CABG, myocardial infarction, stroke, repeat revascularization, and death. Results: Analysis included 733 patients (366 in the radial artery group, 367 in the saphenous vein group). There was no significant difference in study graft patency at 1 year after CABG (radial artery, 238/266; 89%; 95% confidence interval [CI], 86%-93%; saphenous vein, 239/269; 89%; 95% CI, 85%-93%; adjusted OR, 0.99; 95% CI, 0.56-1.74; P=.98). There were no significant differences in the secondary end points. Conclusion: Among Veterans Affairs patients undergoing first-time elective CABG, the use of a radial artery graft compared with saphenous vein graft did not result in greater 1-year patency. Trial Registration: clinicaltrials.gov Identifier: NCT00054847 ©2011 American Medical Association. All rights reserved. Source

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