@article{hager_tsiatis_davidian_2018, title={Optimal two-stage dynamic treatment regimes from a classification perspective with censored survival data}, volume={74}, ISSN={["1541-0420"]}, DOI={10.1111/biom.12894}, abstractNote={Clinicians often make multiple treatment decisions at key points over the course of a patient's disease. A dynamic treatment regime is a sequence of decision rules, each mapping a patient's observed history to the set of available, feasible treatment options at each decision point, and thus formalizes this process. An optimal regime is one leading to the most beneficial outcome on average if used to select treatment for the patient population. We propose a method for estimation of an optimal regime involving two decision points when the outcome of interest is a censored survival time, which is based on maximizing a locally efficient, doubly robust, augmented inverse probability weighted estimator for average outcome over a class of regimes. By casting this optimization as a classification problem, we exploit well-studied classification techniques such as support vector machines to characterize the class of regimes and facilitate implementation via a backward iterative algorithm. Simulation studies of performance and application of the method to data from a sequential, multiple assignment randomized clinical trial in acute leukemia are presented.}, number={4}, journal={BIOMETRICS}, author={Hager, Rebecca and Tsiatis, Anastasios A. and Davidian, Marie}, year={2018}, month={Dec}, pages={1180–1192} }
 @article{harskamp_alexander_ferguson_hager_mack_englum_wojdyla_schulte_kouchoukos_winter_et al._2016, title={Frequency and Predictors of Internal Mammary Artery Graft Failure and Subsequent Clinical Outcomes Insights From the Project of Ex-vivo Vein Graft Engineering via Transfection (PREVENT) IV Trial}, volume={133}, ISSN={["1524-4539"]}, DOI={10.1161/circulationaha.115.015549}, abstractNote={The internal mammary artery (IMA) is the preferred conduit for bypassing the left anterior descending (LAD) artery in patients undergoing coronary artery bypass grafting. Systematic evaluation of the frequency and predictors of IMA failure and long-term outcomes is lacking.The Project of Ex-vivo Vein Graft Engineering via Transfection (PREVENT) IV trial participants who underwent IMA-LAD revascularization and had 12- to 18-month angiographic follow-up (n=1539) were included. Logistic regression with fast false selection rate methods was used to identify characteristics associated with IMA failure (≥75% stenosis). The relationship between IMA failure and long-term outcomes, including death, myocardial infarction, and repeat revascularization, was assessed with Cox regression. IMA failure occurred in 132 participants (8.6%). Predictors of IMA graft failure were LAD stenosis <75% (odds ratio, 1.76; 95% confidence interval, 1.19-2.59), additional bypass graft to diagonal branch (odds ratio, 1.92; 95% confidence interval, 1.33-2.76), and not having diabetes mellitus (odds ratio, 1.82; 95% confidence interval, 1.20-2.78). LAD stenosis and additional diagonal graft remained predictive of IMA failure in an alternative model that included angiographic failure or death before angiography as the outcome. IMA failure was associated with a significantly higher incidence of subsequent acute (<14 days of angiography) clinical events, mostly as a result of a higher rate of repeat revascularization.IMA failure was common and associated with higher rates of repeat revascularization, and patients with intermediate LAD stenosis or with an additional bypass graft to the diagonal branch had increased risk for IMA failure. These findings raise concerns about competitive flow and the benefit of coronary artery bypass grafting in intermediate LAD stenosis without functional evidence of ischemia.URL: http:/www.clinicaltrials.gov. Unique identifier: NCT00042081.}, number={2}, journal={CIRCULATION}, author={Harskamp, Ralf E. and Alexander, John H. and Ferguson, T. Bruce, Jr. and Hager, Rebecca and Mack, Michael J. and Englum, Brian and Wojdyla, Daniel and Schulte, Phillip J. and Kouchoukos, Nicholas T. and Winter, Robbert J. and et al.}, year={2016}, month={Jan}, pages={131–138} }
 @misc{harskamp_alexander_ferguson_hager_mack_englum_wojdyla_schulte_kouchoukos_winter_et al._2016, title={Response to letters regarding article, "Frequency and Predictors of Internal Mammary Artery Graft Failure and Subsequent Clinical Outcomes: Insights From the Project of Ex-Vivo Vein Graft Engineering via Transfection (PREVENT) IV Trial"}, volume={133}, number={21}, journal={Circulation (New York, N.Y. : 1950)}, author={Harskamp, R. E. and Alexander, J. H. and Ferguson, T. B. and Hager, R. and Mack, M. J. and Englum, B. and Wojdyla, D. and Schulte, P. J. and Kouchoukos, N. T. and Winter, R. J. and et al.}, year={2016}, pages={e665–665} }