Special topics.
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Cardiovascular Diseases↗
Biomedical subjects
Frederic S Resnic
Publications and source records attributed to Frederic S Resnic.
Prognosis in critical care.
Prognostic risk prediction models have been employed in the intensive care unit (ICU) setting since the 1980s and provide health care providers with important information to help inform decisions related to treatment and prognosis, as well as to compare outcomes across institutions. Prognostic models for critical care are among the most widely utilized and tested predictive models in healthcare. In this article, we review and compare mortality prediction models, including the APACHE (1981), SAPS (1984), APACHE-II (1985), MPM (1987), APACHE-III (1991), SAPS-II (1993), and MPM-II (1993). We emphasize the importance of model calibration in this domain. In addition, we present a brief review of the statistical methodology, multiple logistic regression, which underlies most of the models currently used in critical care.
Artificial Intelligence↗
Monitoring device safety in interventional cardiology.
OBJECTIVE: A variety of postmarketing surveillance strategies to monitor the safety of medical devices have been supported by the U.S. Food and Drug Administration, but there are few systems to automate surveillance. Our objective was to develop a system to perform real-time monitoring of safety data using a variety of process control techniques. DESIGN: The Web-based Data Extraction and Longitudinal Time Analysis (DELTA) system imports clinical data in real-time from an electronic database and generates alerts for potentially unsafe devices or procedures. The statistical techniques used are statistical process control (SPC), logistic regression (LR), and Bayesian updating statistics (BUS). MEASUREMENTS: We selected in-patient mortality following implantation of the Cypher drug-eluting coronary stent to evaluate our system. Data from the University of Michigan Consortium Bare-Metal Stent Study was used to calculate the event rate alerting boundaries. Data analysis was performed on local catheterization data from Brigham and Women's Hospital from July 1, 2003, shortly after the Cypher release, to December 31, 2004, including 2,270 cases with 27 observed deaths. RESULTS: The single-stratum SPC had alerts in months 4 and 10. The multistrata SPC had alerts in months 5, 10, and 18 in the moderate-risk stratum, and months 1, 4, 7, and 10 in the high-risk stratum. The only cumulative alerts were in the first month for the high-risk stratum of the multistrata SPC. The LR method showed no monthly or cumulative alerts. The BUS method showed an alert in the first month for the high-risk stratum. CONCLUSION: The system performed adequately within the Brigham and Women's Hospital Intranet environment based on the design goals. All three cumulative methods agreed that the overall observed event rates were not significantly higher for the new medical device than for a closely related medical device and were consistent with the observation that the initial concerns about this device dissipated as more data accumulated.
Bayes Theorem↗
Effect of stent implantation on upstream coronary artery compliance--a cause of late plaque rupture?
Stent implantation in the rabbit aorta has been shown to increase vessel wall compliance at the inflow to the stent, but it is uncertain whether similar effects might be seen in the coronary arteries of humans and whether this would have any significant clinical consequences. First, we measured vessel compliance (systolic lumen area--diastolic lumen area/pulse pressure) before, immediately after, and at the 6-month follow-up visit at a site 5 mm upstream of the proximal edge of an implanted coronary stent in patients undergoing coronary intervention using motorized pull-back intravascular ultrasound recordings. Compliance in the upstream segment increased significantly immediately after stenting (before 7.13 +/- 1.49 vs after 10.73 +/- 1.36 mm2/mm Hg, p = 0.03), an effect that was unchanged at 6 months of follow-up (11.84 +/- 2.11 mm2/mm Hg, p = 0.08 vs before stenting). Second, we examined the site of plaque rupture in all patients presenting with an acute coronary syndrome in whom the culprit lesion was in a vessel that had had a stent implanted >12 months previously (n = 31). Plaque rupture was statistically more likely at the inflow to the stent (n = 22) than at other sites within the culprit vessel (n = 9, p <0.01). We conclude that stenting causes an increase in vessel compliance immediately proximal to the stent, and that when a vessel has been previously stented, plaque rupture is most likely to occur at the stent inflow site.
Aged↗
A global goodness-of-fit test for receiver operating characteristic curve analysis via the bootstrap method.
OBJECTIVE: Medical classification accuracy studies often yield continuous data based on predictive models for treatment outcomes. A popular method for evaluating the performance of diagnostic tests is the receiver operating characteristic (ROC) curve analysis. The main objective was to develop a global statistical hypothesis test for assessing the goodness-of-fit (GOF) for parametric ROC curves via the bootstrap. DESIGN: A simple log (or logit) and a more flexible Box-Cox normality transformations were applied to untransformed or transformed data from two clinical studies to predict complications following percutaneous coronary interventions (PCIs) and for image-guided neurosurgical resection results predicted by tumor volume, respectively. We compared a non-parametric with a parametric binormal estimate of the underlying ROC curve. To construct such a GOF test, we used the non-parametric and parametric areas under the curve (AUCs) as the metrics, with a resulting p value reported. RESULTS: In the interventional cardiology example, logit and Box-Cox transformations of the predictive probabilities led to satisfactory AUCs (AUC=0.888; p=0.78, and AUC=0.888; p=0.73, respectively), while in the brain tumor resection example, log and Box-Cox transformations of the tumor size also led to satisfactory AUCs (AUC=0.898; p=0.61, and AUC=0.899; p=0.42, respectively). In contrast, significant departures from GOF were observed without applying any transformation prior to assuming a binormal model (AUC=0.766; p=0.004, and AUC=0.831; p=0.03), respectively. CONCLUSIONS: In both studies the p values suggested that transformations were important to consider before applying any binormal model to estimate the AUC. Our analyses also demonstrated and confirmed the predictive values of different classifiers for determining the interventional complications following PCIs and resection outcomes in image-guided neurosurgery.
Adolescent↗
Exploration of a Bayesian updating tool to provide real-time safety monitoring for new medical devices.
Data Extraction and Longitudinal Time Analysis (DELTA) was developed to provide real-time safety monitoring of new devices in the domain of interventional cardiology. This field provides the necessary infrastructure for this type of endeavor. The American College of Cardiology National Cardiovascular Data Repository (ACC-NCDR) provides a national standardized data dictionary, and there is point of care data collection in many centers. The tool utilizes both Bayesian statistical updating and classical frequentist methods for automated event rate monitoring.
Bayes Theorem↗
Comparison of the risk of vascular complications associated with femoral and radial access coronary catheterization procedures in obese versus nonobese patients.
In this retrospective review of 5,234 cardiac catheterizations and percutaneous coronary interventions, the rate of vascular complications was highest in extremely thin and morbidly obese patients and lowest in moderately obese patients, consistent with the previously reported "obesity paradox." The use of transradial access and arterial access closure devices was associated with reduced vascular complications in the population of obese patients.
Aged↗
No-reflow is an independent predictor of death and myocardial infarction after percutaneous coronary intervention.
BACKGROUND: No-reflow occurring during percutaneous coronary intervention (PCI) has been associated with poor inhospital outcomes. The objectives of this analysis were to evaluate the occurrence of no-reflow as an independent predictor of adverse events and to determine whether treatment with intracoronary vasodilator therapy affected clinical outcomes. METHODS: We prospectively collected data from 4264 consecutive patients undergoing PCI, identifying those with no-reflow, and analyzed their treatments and clinical outcomes. RESULTS: No-reflow was identified in 135 of 4264 patients (3.2%). Baseline demographics were comparable, but patients with no-reflow were more likely to have acute myocardial infarction, unstable angina, and cardiogenic shock and to have undergone saphenous vein graft interventions. No-reflow was highly predictive of postprocedural myocardial infarction (17.7% vs 3.5% in patients without no-reflow, P <.001) and death (7.4% vs 2.0%, P <.001) and remained a strong independent predictor of death or myocardial infarction after multivariate analysis (odds ratio 3.6, P <.001). The administration of intracoronary verapamil, sodium nitroprusside, or both was not associated with a reduction in the rate of death or myocardial infarction (adjusted odds ratio of death or myocardial infarction 1.04, P =.945 for nitroprusside; and adjusted odds ratio of death or myocardial infarction 0.94, P =.91 for verapamil), despite an improvement in angiographic flow rates for patients treated with sodium nitroprusside. CONCLUSIONS: No-reflow is a strong independent predictor of inhospital mortality and postprocedural myocardial infarction. Administration of verapamil or sodium nitroprusside was not associated with improved inhospital outcomes in patients with no-reflow, although anterograde flow rates were improved in patients treated with sodium nitroprusside.
Aged↗
Exploration of a bayesian updating methodology to monitor the safety of interventional cardiovascular procedures.
Appropriate methods for monitoring of the safety of medical devices introduced into clinical practice have been elusive to develop and implement. A novel approach is the application of Bayesian updating, which incorporates existing knowledge regarding event rates into the estimation of risk. This framework has been shown in other domains to be data efficient and to address some of the limitations of conventional statistical methods. In this article, the authors propose a methodologic framework for developing initial prior probability distributions in risk-stratified patient groups and a mechanism for incorporating accumulating procedure safety experience. In addition, they use this methodology to retrospectively analyze the clinical outcomes of 309 patients undergoing an infrequent interventional cardiology procedure, rotational atherectomy. These exploratory analyses demonstrate the feasibility of Bayesian updating applied to medical device safety evaluation and indicate that the methodology is capable of generating stable estimates of risk in a variety of patient risk groups.
Atherectomy, Coronary↗