title: A retrospective comparison of mortality in critically ill hospitalized patients undergoing echocardiography with and without an ultrasound contrast agent.
abstract: OBJECTIVE
  To compare acute mortality in critically ill hospitalized patients undergoing echocardiography with and without an ultrasound contrast agent (UCA).
  
  
  BACKGROUND
  Because of serious cardiopulmonary reactions reported immediately after administration of perflutren-containing UCAs, the FDA required a black box safety warning for this class of agents, including perflutren protein-type A microspheres injectable suspension.
  
  
  METHODS
  This study used the largest hospital service-level database in the U.S. All adult patients undergoing in-patient echocardiography between January 2003 and October 2005 were identified (n = 2,588,722, of which 22,499 received perflutren protein-type A microspheres injectable suspension). Of the 22,499 contrast echocardiography patients, 2,900 had diagnoses meeting criteria for critical illness (heart failure, acute myocardial infarction, arrhythmia, respiratory failure, pulmonary embolism, emphysema, and pulmonary hypertension). To control for the differences between the contrast and noncontrast patients, we used propensity score matching. Variables used in the construction of the propensity score included comorbidities, demographic factors, hospital-specific factors, level of care, and mechanical ventilation status. Patients receiving contrast echocardiography were matched to 4 control patients who received noncontrast echocardiography. Conditional logistic regression was used to estimate mortality effects.
  
  
  RESULTS
  There were 167 deaths in the study among critically ill patients, 38 of 2,900 from the contrast group and 129 of 11,600 from the control group. The contrast agent was not associated with an increase in same-day mortality (odds ratio: 1.18; 95% confidence interval: 0.82 to 1.71; p = 0.37). Before matching, contrast patients showed greater morbidity than noncontrast patients (Deyo-Charlson comorbidity score 2.45 vs. 2.25, p < 0.0001). After propensity score matching, these differences were significantly reduced, showing that both groups were well balanced.
  
  
  CONCLUSIONS
  There is no increase in mortality in critically ill patients undergoing echocardiography with the UCA compared with case-matched control patients.
authors.affiliation: ICON Clinical Research, San Francisco, California, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Exuzides
authors.forename: Michael L
authors.initials: ML
authors.lastname: Main
authors.forename: Chris
authors.initials: C
authors.lastname: Colby
authors.forename: Paul A
authors.initials: PA
authors.lastname: Grayburn
authors.forename: Steven B
authors.initials: SB
authors.lastname: Feinstein
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Goldman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015897:Comorbidity; D003287:Contrast Media / Q000009:adverse effects*; D016638:Critical Illness; D019992:Databases as Topic; D004452:Echocardiography / Q000401:mortality*; D005260:Female; D005466:Fluorocarbons / Q000009:adverse effects*; D017052:Hospital Mortality; D006801:Humans; D007297:Inpatients / Q000706:statistics & numerical data*; D016015:Logistic Models; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D016017:Odds Ratio; D057216:Propensity Score; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren