Eric D. Peterson

The society of thoracic surgeons: 30-day operative mortality and morbidity risk models

BACKGROUND Although 30 day risk-adjusted operative mortality (ROM) has been used for quality assessment, it is not sufficient to describe the outcomes after coronary artery bypass grafting (CABG) surgery. Risk-adjusted major morbidity may differentially impact quality of care (as complications occur more frequently than death) and enhance a surgical teams ability to assess their quality. This study identified the preoperative risk factors associated with several complications and a composite outcome (the presence of any major morbidity or 30-day operative mortality or both). METHODS For CABG procedures, the 1997 to 1999 Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database was used to develop ROM and risk-adjusted morbidity (ROMB) models. Risk factors were selected using standard STS univariate screening and multivariate logistic regression approaches. Risk model performance was assessed. Across STS participating sites, the association of observed-to-expected (O/E) ratios for ROM and ROMB was evaluated. RESULTS The 30-day operative death and major complication rates for STS CABG procedures were 3.05% and 13.40%, respectively (503,478 CABG procedures), including stroke (1.63%), renal failure (3.53%), reoperation (5.17%), prolonged ventilation (5.96%), and sternal infection (0.63%). Risk models were developed (c-indexes for stroke [0.72], renal failure [0.76], reoperation [0.64], prolonged ventilation [0.75], sternal infection [0.66], and the composite endpoint [0.71]). Only a slight correlation was found, however, between ROMB and ROM indicators. CONCLUSIONS Used in combination, ROMB and ROM may provide the surgical team with additional information to evaluate the quality of their care as well as valuable insights to allow them to focus on areas for improvement.

Use of a Prognostic Treadmill Score in Identifying Diagnostic Coronary Disease Subgroups

BACKGROUND Exercise testing is useful in the assessment of symptomatic patients for diagnosis of significant or extensive coronary disease and to predict their future risk of cardiac events. The Duke treadmill score (DTS) is a composite index that was designed to provide survival estimates based on results from the exercise test, including ST-segment depression, chest pain, and exercise duration. However, its usefulness for providing diagnostic estimates has yet to be determined. METHODS AND RESULTS A logistic regression model was used to predict significant (>/=75% stenosis) and severe (3-vessel or left main) coronary artery disease, and a Cox regression analysis was used to predict cardiac survival. After adjustment for baseline clinical risk, the DTS was effectively diagnostic for significant (P<0.0001) and severe (P<0.0001) coronary artery disease. For low-risk patients (score >/=+5), 60% had no coronary stenosis >/=75% and 16% had single-vessel >/=75% stenosis. By comparison, 74% of high-risk patients (score <-11) had 3-vessel or left main coronary disease. Five-year mortality was 3%, 10%, and 35% for low-, moderate-, and high-risk DTS groups (P<0.0001). CONCLUSIONS The composite DTS provides accurate diagnostic and prognostic information for the evaluation of symptomatic patients evaluated for clinically suspected ischemic heart disease.

Regional gray matter volumetric changes in autism associated with social and repetitive behavior symptoms

BackgroundAlthough differences in brain anatomy in autism have been difficult to replicate using manual tracing methods, automated whole brain analyses have begun to find consistent differences in regions of the brain associated with the social cognitive processes that are often impaired in autism. We attempted to replicate these whole brain studies and to correlate regional volume changes with several autism symptom measures.MethodsWe performed MRI scans on 24 individuals diagnosed with DSM-IV autistic disorder and compared those to scans from 23 healthy comparison subjects matched on age. All participants were male. Whole brain, voxel-wise analyses of regional gray matter volume were conducted using voxel-based morphometry (VBM).ResultsControlling for age and total gray matter volume, the volumes of the medial frontal gyri, left pre-central gyrus, right post-central gyrus, right fusiform gyrus, caudate nuclei and the left hippocampus were larger in the autism group relative to controls. Regions exhibiting smaller volumes in the autism group were observed exclusively in the cerebellum. Significant partial correlations were found between the volumes of the caudate nuclei, multiple frontal and temporal regions, the cerebellum and a measure of repetitive behaviors, controlling for total gray matter volume. Social and communication deficits in autism were also associated with caudate, cerebellar, and precuneus volumes, as well as with frontal and temporal lobe regional volumes.ConclusionGray matter enlargement was observed in areas that have been functionally identified as important in social-cognitive processes, such as the medial frontal gyri, sensorimotor cortex and middle temporal gyrus. Additionally, we have shown that VBM is sensitive to associations between social and repetitive behaviors and regional brain volumes in autism.

Exploring the Behavior of Hospital Composite Performance Measures An Example From Coronary Artery Bypass Surgery

Background— Composite scores that combine several performance measures into a single ranking are becoming the accepted metric for assessing hospital performance. In particular, the Centers for Medicare & Medicaid Services Hospital Quality Incentive Demonstration (HQID) project bases financial rewards and penalties on these scores. Although the HQID composite calculation is straightforward and easily understood, its method of combining process and outcome measures has not been validated. Methods and Results— Using data on 530 hospitals from the Society of Thoracic Surgeons National Cardiac Database, we replicated the HQID methodology with 6 nationally endorsed performance measures (5 process measures plus survival) for coronary artery bypass surgery. Composite scores were essentially determined by process measure performance alone; the survival component explained only 4% of the composite score’s total variance. This result persisted even when the survival component was allowed a 5-fold greater weighting in the composite summary. The popular “all-or-none” measurement approach was also dominated by the process component. Substantial disagreement was found among hospital rankings when several alternative methods were used; up to 60% of hospitals eligible for the top financial reward under HQID would change designation depending on the composite methodology used. The application of a simple statistical adjustment (standardization) to each method would provide more consistent results and a more balanced assessment of performance based on both process and outcomes. Conclusions— Existing methods used to create composite performance measures have remarkably different weighting of process versus outcomes metrics and lead to highly divergent provider rankings. Simple alternative methods can create more balanced process-outcome performance assessments.