Increased CT use over the 15-year study period resulted in increased radiation exposure, doubling mean per capita effective dose (1.2 mSv to 2.3 mSv), as well as those receiving high exposure (1.2% to 2.5%) and very high exposure (0.6% to 1.4%).
The increased imaging use and radiation exposure among HMO enrollees was similar to that of fee-for-service Medicare patients in previous studies.
Bottom line: There is a significant increase in use of diagnostic imaging studies and associated radiation exposure among integrated healthcare system enrollees from 1996 to 2010, similar to patients in fee-for-service health plans.
Citation: Smith-Bindman R, Miglioretti DL, Johnson E, et al. Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996-2010. JAMA. 2012;307(22):2400-2409.
Postoperative Troponin Predicts 30-Day Mortality
Clinical question: Does postoperative peak troponin level predict 30-day mortality in patients undergoing noncardiac surgery?
Background: The use of postoperative peak troponin levels in predicting 30-day mortality for patients undergoing noncardiac surgery has not been studied extensively. Identifying patients at high risk for death following noncardiac surgery could facilitate appropriate postoperative care and improve survival.
Study design: Prospective cohort study.
Setting: International university and nonuniversity hospitals.
Synopsis: The Vascular Events In Noncardiac Surgery Patients Cohort Evaluation (VISION) Study is a large, international, multicenter, prospective cohort study designed to evaluate the major complications of noncardiac surgery. More than 15,100 patients ages 45 and older requiring at least an overnight hospitalization were enrolled following noncardiac surgery.
Peak troponin measurements during the first three postoperative days of 0.01 ng/ml or less, 0.02 ng/ml, 0.03 ng/ml to 0.29 ng/ml, and 0.3 ng/ml or greater had 30-day mortality rates of 1.0%, 4.0%, 9.3%, and 16.9%, respectively.
This study demonstrates the sensitivity of troponin measurement for predicting postoperative 30-day mortality in patients undergoing noncardiac surgery. The study does not address interventions based on an increased postoperative troponin level. Future studies might investigate postoperative modifiable risk factors.
Bottom line: Postoperative peak troponin level predicts 30-day mortality in patients undergoing noncardiac surgery.
Citation: Devereaux PJ, Chan MT, Alonso-Coello P, et al. Association between postoperative troponin levels and 30-day mortality among patients undergoing noncardiac surgery. JAMA. 2012;307(21):2295-2304.
Clinical Prediction Model of Mortality in Acute Heart Failure
Clinical question: Can a clinical prediction model accurately risk-stratify patients presenting to the ED with acute heart failure?
Background: Accurately prognosticating mortality is essential when determining whether to hospitalize or discharge patients presenting to the ED with acute heart failure. Evidence-based clinical prediction models enable physicians to risk-stratify patients and optimize care.
Study design: Retrospective cohort study.
Setting: Multicenter study of 86 hospitals in Ontario, Canada.
Synopsis: Data collected from 12,591 patients who presented to EDs with acute heart failure in Ontario were analyzed. A clinical prediction model of seven-day mortality of discharged and hospitalized patients was derived and validated. The Emergency Heart Failure Mortality Risk Grade (EHMRG) found an increased mortality based on higher triage heart rate, lower triage systolic blood pressure, initial oxygen saturation, and elevated troponin levels. This model uses readily available data collected in ED visits. The high-risk EHMRG score predicted about 8% seven-day mortality versus 0.3% in the low-risk score.
This model was not applied to chronic heart failure, did not utilize left ventricular function, and does not differentiate between systolic and diastolic heart failure.
Bottom line: The Emergency Heart Failure Mortality Risk Grade predicts seven-day mortality in acute heart failure in the emergent setting.
Citation: Lee DS, Stitt A, Austin PC, et al. Prediction of heart failure mortality in emergent care: a cohort study. Ann Intern Med. 2012;156(11):767-775.