Optimal two-stage dynamic treatment regimes from a classification perspective with censored survival data.

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.

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.

BACKGROUND: 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. METHODS AND RESULTS: 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. CONCLUSIONS: 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. CLINICAL TRIAL REGISTRATION: URL: http:/www.clinicaltrials.gov. Unique identifier: NCT00042081.

Saphenous vein graft failure after coronary artery bypass surgery: insights from PREVENT IV.

BACKGROUND: Coronary artery bypass grafting success is limited by vein graft failure (VGF). Understanding the factors associated with VGF may improve patient outcomes. METHODS AND RESULTS: We examined 1828 participants in the Project of Ex Vivo Vein Graft Engineering via Transfection IV (PREVENT IV) trial undergoing protocol-mandated follow-up angiography 12 to 18 months post-coronary artery bypass grafting or earlier clinically driven angiography. Outcomes included patient- and graft-level angiographic VGF (≥75% stenosis or occlusion). Variables were selected by using Fast False Selection Rate methodology. We examined relationships between variables and VGF in patient- and graft-level models by using logistic regression without and with generalized estimating equations. At 12 to 18 months post-coronary artery bypass grafting, 782 of 1828 (42.8%) patients had VGF, and 1096 of 4343 (25.2%) vein grafts had failed. Demographic and clinical characteristics were similar between patients with and without VGF, although VGF patients had longer surgical times, worse target artery quality, longer graft length, and they more frequently underwent endoscopic vein harvesting. After multivariable adjustment, longer surgical duration (odds ratio per 10-minute increase, 1.05; 95% confidence interval, 1.03-1.07), endoscopic vein harvesting (odds ratio, 1.41; 95% confidence interval, 1.16-1.71), poor target artery quality (odds ratio, 1.43; 95% confidence interval, 1.11-1.84), and postoperative use of clopidogrel or ticlopidine (odds ratio, 1.35; 95% confidence interval, 1.07-1.69) were associated with patient-level VGF. The predicted likelihood of VGF in the graft-level model ranged from 12.1% to 63.6%. CONCLUSIONS: VGF is common and associated with patient and surgical factors. These findings may help identify patients with risk factors for VGF and inform the development of interventions to reduce VGF. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00042081.

Meta-analysis of intracranial hemorrhage in acute coronary syndromes: incidence, predictors, and clinical outcomes.

BACKGROUND: Little is known about the incidence, predictors, or outcomes of intracranial hemorrhage (ICH) in patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS). We aimed to determine the incidence and timing of ICH, characterize the location of ICH, and identify independent baseline predictors of ICH in NSTE ACS patients. METHODS AND RESULTS: We pooled patient-level data from 4 contemporary antithrombotic therapy trials. Multivariable modeling identified independent predictors of ICH. ICHs were adjudicated by a clinical events committee. Of 37 815 patients, 135 (0.4%) had an ICH. The median (25th, 75th percentiles) follow-up was 332 (184, 434) days but differed across trials. Locations of ICH were intracerebral (50%), subdural (31%), subarachnoid (18.5%), and intraventricular (11%). Independent predictors of ICH were older age (HR per 10 years, 1.61; 95% CI, 1.35 to 1.91); prior stroke/transient ischemic attack; HR, 1.95; 95% CI, 1.14 to 3.35), higher systolic blood pressure; HR per 10 mm Hg increase, 1.09; 95% CI, 1.01 to 1.18), and larger number of antithrombotic agents (HR per each additional agent, 2.06; 95% CI, 1.49 to 2.84). Of all ICHs, 45 (33%) were fatal. CONCLUSIONS: In patients with NSTE ACS enrolled in recent clinical trials of antithrombotic therapies, ICH was uncommon. Patients with older age, prior transient ischemic attack/stroke, higher systolic blood pressure, or larger number of antithrombotic agents were at increased risk. One-third of patients with ICH died. These data may be useful to trialists and data and safety monitoring committees for trial conduct and monitoring. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov/. Unique identifiers: TRACER: NCT00527943, PLATO: NCT00391872, APPRAISE-2: NCT00831441, TRILOGY ACS: NCT00699998.