Bruce Cooil

Identification of Patients at Increased Risk of First Unheralded Acute Myocardial Infarction by Electron-Beam Computed Tomography

BACKGROUND There is a clear relationship between absolute calcium scores (CS) and severity of coronary artery disease. However, hard coronary events have been shown to occur across all ranges of CS. METHODS AND RESULTS We conducted 2 analyses: in group A, 172 patients underwent electron-beam CT (EBCT) imaging within 60 days of suffering an unheralded myocardial infarction. In group B, 632 patients screened by EBCT were followed up for a mean of 32+/-7 months for the development of acute myocardial infarction or cardiac death. The mean patient age and prevalence of coronary calcification were similar in the 2 groups (53+/-8 versus 52+/-9 years and 96% each). In group B, the annualized event rate was 0.11% for subjects with CS of 0, 2.1% for CS 1 to 99, 4.1% for CS 100 to 400, and 4.8% for CS >400, and only 7% of the patients had CS >400. However, mild, moderate, and extensive absolute CSs were distributed similarly between patients with events in both groups (34%, 35%, and 27%, respectively, in group A and 44%, 30%, and 22% in group B). In contrast, the majority of events in both groups occurred in patients with CS >75th percentile (70% in each group). CONCLUSIONS Coronary calcium is present in most patients who suffer acute coronary events. Although the event rate is greater for patients with high absolute CSs, few patients have this degree of calcification on a screening EBCT. Conversely, the majority of events occur in individuals with high CS percentiles. Hence, CS percentiles constitute a more effective screening method to stratify individuals at risk.

Effect of HMG-CoA Reductase Inhibitors on Coronary Artery Disease as Assessed by Electron-Beam Computed Tomography

BACKGROUND Angiographic studies of the regression of coronary artery disease are invasive and costly, and they permit only limited assessment of changes in the extent of atherosclerotic disease. Electron-beam computed tomography (CT) is noninvasive and inexpensive. The entire coronary-artery tree can be studied during a single imaging session, and the volume of coronary calcification as quantified with this technique correlates closely with the total burden of atherosclerotic plaque. METHODS We conducted a retrospective study of 149 patients (61 percent men and 39 percent women; age range, 32 to 75 years) with no history of coronary artery disease who were referred by their primary care physicians for screening electron-beam CT. All patients underwent base-line scanning and follow-up assessment after a minimum of 12 months (range, 12 to 15), and a volumetric calcium score was calculated as an estimate of the total burden of plaque. Treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors was begun at the discretion of the referring physician. Serial measurements of low-density lipoprotein (LDL) cholesterol were obtained, and the change in the calcium-volume score was correlated with average LDL cholesterol levels. RESULTS One hundred five patients (70 percent) received treatment with HMG-CoA reductase inhibitors, and 44 patients (30 percent) did not. At follow-up, a net reduction in the calcium-volume score was observed only in the 65 treated patients whose final LDL cholesterol levels were less than 120 mg per deciliter (3.10 mmol per liter) (mean [+/-SD] change in the score, -7+/-23 percent; P=0.01). Untreated patients had an average LDL cholesterol level of at least 120 mg per deciliter and at the time of follow-up had a significant net increase in mean calcium-volume score (mean change, +52+/-36 percent; P<0.001). The 40 treated patients who had average LDL cholesterol levels of at least 120 mg per deciliter had a measurable increase in mean calcium-volume score (25+/-22 percent, P<0.001), although it was smaller than the increase in the untreated patients. CONCLUSIONS The extent to which the volume of atherosclerotic plaque decreased, stabilized, or increased was directly related to treatment with HMG-CoA reductase inhibitors and the resulting serum LDL cholesterol levels. These changes can be determined noninvasively by electron-beam CT and quantified with use of a calcium-volume score.

Progression of coronary calcium on serial electron beam tomographic scanning is greater in patients with future myocardial infarction

We conducted an observational study relating the occurrence of acute myocardial infarction (MI) to coronary artery calcium progression in 817 asymptomatic subjects referred for sequential electron beam tomographic imaging (average interval 2.2 +/- 1.3 years). A calcium volume score (CVS) was used for plaque quantification. The yearly mean absolute and percent CVS changes in the 45 patients who had a MI were 147 +/- 152 and 47 +/- 50%, respectively, compared with 63 +/- 128 and 26 +/- 32%, respectively (p <0.001, p = 0.01), in patients without events.

The Long Term Stock Market Valuation of Customer Satisfaction

Firm valuation has been an important domain of interest for finance. However, most financial models do not include customer-related metrics in this process. Studies in marketing have found that one particular customer metric, customer satisfaction, improves the ability to predict future cash flows, long-term financial measures, stock performance, and shareholder value. However, most of these studies predominantly employ models that are not directly used in finance practice. This article extends existing literature by examining the impact of customer satisfaction on firm valuation by employing multiples and risk-adjusted abnormal return models borrowed directly from the practice of finance. Data include 3600 firm-quarter observations from the American Customer Satisfaction Index, COMPUSTAT, and Center for Research in Securities Prices databases from 1996 to 2006. The results indicate that a portfolio of stocks consisting of firms with high levels and positive changes in customer satisfaction will outperform the other three possible portfolio combinations (low levels and negative changes, low levels and positive changes, and high levels and negative changes in customer satisfaction) along with Standard & Poors 500. Initially, the stock market undervalues positive satisfaction information, but the market adjusts in the long run.

Progression of Coronary Artery Calcium and Occurrence of Myocardial Infarction in Patients With and Without Diabetes Mellitus

Progression of coronary artery calcium, a marker of atherosclerosis, can be slowed with statins, and continued progression of calcium is associated with an increased risk of myocardial infarction. However, it is not known whether statins are effective in slowing calcium progression in diabetes mellitus. In a retrospective study, we examined 1153 nondiabetic and 157 diabetic subjects who underwent sequential electron beam tomography scans at a minimum 1-year interval to assess progression of coronary calcium. A yearly score increase >15% was considered evidence of true progression. The use of statins and occurrence of myocardial infarction were recorded. There was no difference in baseline calcium score between diabetic and nondiabetic patients. Diabetic patients with no coronary calcium on the baseline scans developed it more often than nondiabetic subjects (42% versus 25%; P=0.046) during follow-up. Calcium progression was 33% greater in diabetic patients than nondiabetic subjects (P<0.001) if no statin therapy was provided and 17.7% greater when statins were used (P<0.001). Among the 49 subjects who experienced a myocardial infarction, the calcium score increased on average 20% more in diabetic than nondiabetic patients (P<0.001). In logistic models, diabetes mellitus and systemic hypertension were the best predictors of calcium progression (odds ratio, 3.1 and 1.9, respectively), whereas baseline calcium score percentile and statin therapy were the best predictors of infarction. These findings support the notion that diabetes mellitus causes accelerated atherosclerosis, even in the presence of statin therapy, and provide evidence that coronary calcium monitoring is an effective method to assess treatment efficacy.

Should Recommendation Agents Think Like People

Electronic recommendation agents have the potential to increase the level of service provided by firms operating in the online environment. Recommendation agents assist consumers in making product decisions by generating rank-ordered alternative lists based on consumer preferences. However, many of the online agents currently in use rank options in different ways than the consumers they are designed to help. Two experiments examine the role of similarity between an electronic agent and a consumer, in terms of actual similarity of attribute weights and perceived similarity of decision strategies, on the quality of consumer choices. Results indicate that it helps consumers to use a recommendation agent that thinks like them, either in terms of attribute weights or decision strategies. When agents are completely dissimilar, consumers may be no better, and sometimes worse off, using an agent’s ordered list than if they simply used a randomly ordered list of options.

Evaluation of chest pain in patients with low to intermediate pretest probability of coronary artery disease by electron beam computed tomography

Despite its limited sensitivity and specificity in patients with low to intermediate probability of coronary artery disease (CAD), exercise treadmill testing (ETT) is frequently used as the initial test for investigation of chest pain. Although myocardial perfusion imaging is a significantly more accurate test, its added cost to ETT is considerable. The cost of a non-contrast electron beam computed tomography (EBCT) scan is comparable to that of ETT and the calcium score (CS) correlates closely with the volume of atherosclerotic plaque. Therefore, we tested the hypothesis that EBCT might be an effective and cost-beneficial technique for the identification of angiographically obstructive CAD (> or = 50% stenosis) in patients with low to intermediate pretest probability of disease. We calculated the theoretic cost of attaining a diagnosis of CAD based on a Bayesian model that utilizes published sensitivity and specificity levels for ETT, EBCT, and stress myocardial perfusion imaging. We then submitted a cohort of 207 patients with low to intermediate probability of disease both to EBCT and ETT in random order, and estimated the cost of achieving a correct diagnosis by either route based on the number of expected further tests. An EBCT calcium score of 150 was chosen as a cut-point with a sensitivity of 74% and a specificity of 89% for the presence of obstructive CAD. The theoretic Bayesian model predicted substantial cost savings when EBCT was used as the initial test instead of ETT, with decreasing benefit as the prevalence of disease increased (44% saving at 0% prevalence; 15% saving at 100% prevalence). In the patient cohort, the diagnostic pathway starting with EBCT provided a 45% to 65% cost saving over the ETT pathway. We conclude that in patients with low to intermediate pretest probability of disease, a pathway based on EBCT as the initial test to investigate presence of obstructive CAD provides a substantial cost benefit over a pathway based on ETT. Such cost advantages decrease as the prevalence of disease increases.

Individual differences in risk perception versus risk taking: handedness and interhemispheric interaction.

Research indicates that right-hemisphere mechanisms are specifically sensitive to and averse to risk. Research also indicates that mixed degree of handedness is associated with increased access to right hemisphere processing. Accordingly, it was predicted that mixed-handers would exhibit greater risk aversion. Participants were presented with various risky activities and were asked to rate (i) the perceived risk, (ii) the perceived benefit, and (iii) their likelihood to engage in each activity. No handedness differences were found for any of these ratings. Regression analyses, however, indicated that the likelihood to engage in risky activities was predicted primarily by the perceived risks in mixed-handers and by the perceived benefits in strong-handers.

The Relationship of Employee Perceptions of Organizational Climate to Business-Unit Outcomes: An MPLS Approach

There has been an extensive exploration of how organizational climate is related to various business outcomes, but these studies have generally examined outcomes separately or developed univariate measures that combine outcomes. These approaches fail to (a) accommodate the multivariate character of important business results and (b) facilitate the firms need to achieve success on several dimensions. This research proposes a methodological approach new to the service domain to address these issues. Using data from a large, multinational retail grocery superstore based in continental Western Europe, this study illustrates how multivariate partial least squares (MPLS) models can be used. MPLS provides three interpretable factors of climate—Overall Organizational Climate, Self-Efficacy Versus Leaders Efficacy, and Personal Empowerment Versus Management Facilitation —that are important predictors of three business outcomes: employee retention, customer satisfaction, and scaled revenue. The use of the MPLS approach in other services domains is also explored.

Call Center Satisfaction and Customer Retention in a Co-Branded Service Context

Purpose – This paper aims to examine call center satisfaction in an escalated call center context where callers are organization members of the primary/leveraged brand and have purchased additional co‐branded services as part of their membership. It also aims to examine the relationship between call center satisfaction and actual retention of both the co‐branded service offered and the primary brand (call center operated by the membership organization).Design/methodology/approach – The survey data used in the analyses involve a sample size of 88 respondents, all members of a large, national nonprofit organization in the USA. Factor analysis and logistic regression were used to test the propositions.Findings – The results indicate that caller satisfaction has four dimensions similar to those found in SERVQUAL. Although call center satisfaction dimensions are not significant for co‐branded service retention, the empathy dimension is most important to primary/leveraged brand retention.Research limitations/im...