Jersey Chen

Exposure to Low-Dose Ionizing Radiation from Medical Imaging Procedures

BACKGROUND The growing use of imaging procedures in the United States has raised concerns about exposure to low-dose ionizing radiation in the general population. METHODS We identified 952,420 nonelderly adults (between 18 and 64 years of age) in five health care markets across the United States between January 1, 2005, and December 31, 2007. Utilization data were used to estimate cumulative effective doses of radiation from imaging procedures and to calculate population-based rates of exposure, with annual effective doses defined as low (< or = 3 mSv), moderate (> 3 to 20 mSv), high (> 20 to 50 mSv), or very high (> 50 mSv). RESULTS During the study period, 655,613 enrollees (68.8%) underwent at least one imaging procedure associated with radiation exposure. The mean (+/-SD) cumulative effective dose from imaging procedures was 2.4+/-6.0 mSv per enrollee per year; however, a wide distribution was noted, with a median effective dose of 0.1 mSv per enrollee per year (interquartile range, 0.0 to 1.7). Overall, moderate effective doses of radiation were incurred in 193.8 enrollees per 1000 per year, whereas high and very high doses were incurred in 18.6 and 1.9 enrollees per 1000 per year, respectively. In general, cumulative effective doses of radiation from imaging procedures increased with advancing age and were higher in women than in men. Computed tomographic and nuclear imaging accounted for 75.4% of the cumulative effective dose, with 81.8% of the total administered in outpatient settings. CONCLUSIONS Imaging procedures are an important source of exposure to ionizing radiation in the United States and can result in high cumulative effective doses of radiation.

National and Regional Trends in Heart Failure Hospitalization and Mortality Rates for Medicare Beneficiaries, 1998-2008

CONTEXT It is not known whether recent declines in ischemic heart disease and its risk factors have been accompanied by declines in heart failure (HF) hospitalization and mortality. OBJECTIVE To examine changes in HF hospitalization rate and 1-year mortality rate in the United States, nationally and by state or territory. DESIGN, SETTING, AND PARTICIPANTS From acute care hospitals in the United States and Puerto Rico, 55,097,390 fee-for-service Medicare beneficiaries hospitalized between 1998 and 2008 with a principal discharge diagnosis code for HF. MAIN OUTCOME MEASURES Changes in patient demographics and comorbidities, HF hospitalization rates, and 1-year mortality rates. RESULTS The HF hospitalization rate adjusted for age, sex, and race declined from 2845 per 100,000 person-years in 1998 to 2007 per 100,000 person-years in 2008 (P < .001), a relative decline of 29.5%. Age-adjusted HF hospitalization rates declined over the study period for all race-sex categories. Black men had the lowest rate of decline (4142 to 3201 per 100,000 person-years) among all race-sex categories, which persisted after adjusting for age (incidence rate ratio, 0.81; 95% CI, 0.79-0.84). Heart failure hospitalization rates declined significantly faster than the national mean in 16 states and significantly slower in 3 states. Risk-adjusted 1-year mortality decreased from 31.7% in 1999 to 29.6% in 2008 (P < .001), a relative decline of 6.6%. One-year mortality rates declined significantly in 4 states but increased in 5 states. CONCLUSIONS The overall HF hospitalization rate declined substantially from 1998 to 2008 but at a lower rate for black men. The overall 1-year mortality rate declined slightly over the past decade but remains high. Changes in HF hospitalization and 1-year mortality rates were uneven across states.

Trends in length of stay and short-term outcomes among Medicare patients hospitalized for heart failure, 1993-2006.

CONTEXT Whether decreases in the length of stay during the past decade for patients with heart failure (HF) may be associated with changes in outcomes is unknown. OBJECTIVE To describe the temporal changes in length of stay, discharge disposition, and short-term outcomes among older patients hospitalized for HF. DESIGN, SETTING, AND PARTICIPANTS An observational study of 6,955,461 Medicare fee-for-service hospitalizations for HF between 1993 and 2006, with a 30-day follow-up. MAIN OUTCOME MEASURES Length of hospital stay, in-patient and 30-day mortality, and 30-day readmission rates. RESULTS Between 1993 and 2006, mean length of stay decreased from 8.81 days (95% confidence interval [CI], 8.79-8.83 days) to 6.33 days (95% CI, 6.32-6.34 days). In-hospital mortality decreased from 8.5% (95% CI, 8.4%-8.6%) in 1993 to 4.3% (95% CI, 4.2%-4.4%) in 2006, whereas 30-day mortality decreased from 12.8% (95% CI, 12.8%-12.9%) to 10.7% (95% CI, 10.7%-10.8%). Discharges to home or under home care service decreased from 74.0% to 66.9% and discharges to skilled nursing facilities increased from 13.0% to 19.9%. Thirty-day readmission rates increased from 17.2% (95% CI, 17.1%-17.3%) to 20.1% (95% CI, 20.0%-20.2%; all P < .001). Consistent with the unadjusted analyses, the 2005-2006 risk-adjusted 30-day mortality risk ratio was 0.92 (95% CI, 0.91-0.93) compared with 1993-1994, and the 30-day readmission risk ratio was 1.11 (95% CI, 1.10-1.11). CONCLUSION For patients admitted with HF during the past 14 years, reductions in length of stay and in-hospital mortality, less marked reductions in 30-day mortality, and changes in discharge disposition accompanied by increases in 30-day readmission rates were observed.

Patterns of Hospital Performance in Acute Myocardial Infarction and Heart Failure 30-Day Mortality and Readmission

Background—In 2009, the Centers for Medicare & Medicaid Services is publicly reporting hospital-level risk-standardized 30-day mortality and readmission rates after acute myocardial infarction (AMI) and heart failure (HF). We provide patterns of hospital performance, based on these measures. Methods and Results—We calculated the 30-day mortality and readmission rates for all Medicare fee-for-service beneficiaries ages 65 years or older with a primary diagnosis of AMI or HF, discharged between July 2005 and June 2008. We compared weighted risk-standardized mortality and readmission rates across Hospital Referral Regions and hospital structural characteristics. The median 30-day mortality rate was 16.6% for AMI (range, 10.9% to 24.9%; 25th to 75th percentile, 15.8% to 17.4%; 10th to 90th percentile, 14.7% to 18.4%) and 11.1% for HF (range, 6.6% to 19.8%; 25th to 75th percentile, 10.3% to 12.0%; 10th to 90th percentile, 9.4% to 13.1%). The median 30-day readmission rate was 19.9% for AMI (range, 15.3% to 29.4%; 25th to 75th percentile, 19.5% to 20.4%; 10th to 90th percentile, 18.8% to 21.1%) and 24.4% for HF (range, 15.9% to 34.4%; 25th to 75th percentile, 23.4% to 25.6%; 10th to 90th percentile, 22.3% to 27.0%). We observed geographic differences in performance across the country. Although there were some differences in average performance by hospital characteristics, there were high and low hospital performers among all types of hospitals. Conclusions—In a recent 3-year period, 30-day risk-standardized mortality rates for AMI and HF varied among hospitals and across the country. The readmission rates were particularly high.

An Administrative Claims Measure Suitable for Profiling Hospital Performance on the Basis of 30-Day All-Cause Readmission Rates Among Patients With Heart Failure

Background—Readmission soon after hospital discharge is an expensive and often preventable event for patients with heart failure. We present a model approved by the National Quality Forum for the purpose of public reporting of hospital-level readmission rates by the Centers for Medicare & Medicaid Services. Methods and Results—We developed a hierarchical logistic regression model to calculate hospital risk-standardized 30-day all-cause readmission rates for patients hospitalized with heart failure. The model was derived with the use of Medicare claims data for a 2004 cohort and validated with the use of claims and medical record data. The unadjusted readmission rate was 23.6%. The final model included 37 variables, had discrimination ranging from 15% observed 30-day readmission rate in the lowest predictive decile to 37% in the upper decile, and had a c statistic of 0.60. The 25th and 75th percentiles of the risk-standardized readmission rates across 4669 hospitals were 23.1% and 24.0%, with 5th and 95th percentiles of 22.2% and 25.1%, respectively. The odds of all-cause readmission for a hospital 1 standard deviation above average was 1.30 times that of a hospital 1 standard deviation below average. State-level adjusted readmission rates developed with the use of the claims model are similar to rates produced for the same cohort with the use of a medical record model (correlation, 0.97; median difference, 0.06 percentage points). Conclusions—This claims-based model of hospital risk-standardized readmission rates for heart failure patients produces estimates that may serve as surrogates for those derived from a medical record model.

Association of door-to-balloon time and mortality in patients admitted to hospital with ST elevation myocardial infarction: national cohort study

Objective To evaluate the association between door-to-balloon time and mortality in hospital in patients undergoing primary percutaneous coronary intervention for ST elevation myocardial infarction to assess the incremental mortality benefit of reductions in door-to-balloon times of less than 90 minutes. Design Prospective cohort study of patients enrolled in the American College of Cardiology National Cardiovascular Data Registry, 2005-6. Setting Acute care hospitals. Participants 43 801 patients with ST elevation myocardial infarction undergoing primary percutaneous coronary intervention. Main outcome measure Mortality in hospital. Results Median door-to-balloon time was 83 minutes (interquartile range 6-109, 57.9% treated within 90 minutes). Overall mortality in hospital was 4.6%. Multivariable logistic regression models with fractional polynomial models indicated that longer door-to-balloon times were associated with a higher adjusted risk of mortality in hospital in a continuous non-linear fashion (30 minutes=3.0%, 60 minutes=3.5%, 90 minutes=4.3%, 120 minutes=5.6%, 150 minutes=7.0%, 180 minutes=8.4%, P<0.001). A reduction in door-to-balloon time from 90 minutes to 60 minutes was associated with 0.8% lower mortality, and a reduction from 60 minutes to 30 minutes with a 0.5% lower mortality. Conclusion Any delay in primary percutaneous coronary intervention after a patient arrives at hospital is associated with higher mortality in hospital in those admitted with ST elevation myocardial infarction. Time to treatment should be as short as possible, even in centres currently providing primary percutaneous coronary intervention within 90 minutes.

Do "America's Best Hospitals" perform better for acute myocardial infarction?

Background “Americas Best Hospitals,” an influential list published annually by U.S. News & World Report, assesses the quality of hospitals. It is not known whether patients admitted to hospitals ranked at the top in cardiology have lower short-term mortality from acute myocardial infarction than those admitted to other hospitals or whether differences in mortality are explained by differential use of recommended therapies. Methods Using data from the Cooperative Cardiovascular Project on 149,177 elderly Medicare beneficiaries with acute myocardial infarction in 1994 or 1995, we examined the care and outcomes of patients admitted to three types of hospitals: those ranked high in cardiology (top-ranked hospitals); hospitals not in the top rank that had on-site facilities for cardiac catheterization, coronary angioplasty, and bypass surgery (similarly equipped hospitals); and the remaining hospitals (non–similarly equipped hospitals). We compared 30-day mortality; the rates of use of aspirin, beta-blockers...

Racial Differences in the Use of Cardiac Catheterization after Acute Myocardial Infarction

BACKGROUND Several studies have reported that black patients are less likely than white patients to undergo cardiac catheterization after acute myocardial infarction. The role of the race of the physician in this pattern is unknown. METHODS We analyzed data from the Cooperative Cardiovascular Project, a study of Medicare beneficiaries hospitalized for acute myocardial infarction in 1994 and 1995, to evaluate whether differences between black patients and white patients in the use of cardiac catheterization within 60 days after acute myocardial infarction varied according to the race of their attending physician. RESULTS Our study cohort consisted of 35,676 white and 4039 black patients with acute myocardial infarction who were treated by 17,550 white and 588 black physicians. Black patients had lower rates of cardiac catheterization than white patients, regardless of whether their attending physician was white (rate of catheterization, 38.4 percent vs. 45.7 percent; P< 0.001) or black (38.2 percent vs. 49.6 percent, P<0.001). We did not find a significant interaction between the race of the patients and the race of the physicians in the use of cardiac catheterization. The adjusted mortality rate among black patients was lower than or similar to that among white patients for up to three years after the infarction. CONCLUSIONS Racial differences in the use of cardiac catheterization are similar among patients treated by white physicians and those treated by black physicians, suggesting that this pattern of care is independent of the race of the physician.

Reduction in Acute Myocardial Infarction Mortality in the United States: Risk-Standardized Mortality Rates From 1995-2006

CONTEXT During the last 2 decades, health care professional, consumer, and payer organizations have sought to improve outcomes for patients hospitalized with acute myocardial infarction (AMI). However, little has been reported about improvements in hospital short-term mortality rates or reductions in between-hospital variation in short-term mortality rates. OBJECTIVE To estimate hospital-level 30-day risk-standardized mortality rates (RSMRs) for patients discharged with AMI. DESIGN, SETTING, AND PATIENTS Observational study using administrative data and a validated risk model to evaluate 3,195,672 discharges in 2,755,370 patients discharged from nonfederal acute care hospitals in the United States between January 1, 1995, and December 31, 2006. Patients were 65 years or older (mean, 78 years) and had at least a 12-month history of fee-for-service enrollment prior to the index hospitalization. Patients discharged alive within 1 day of an admission not against medical advice were excluded, because it is unlikely that these patients had sustained an AMI. MAIN OUTCOME MEASURE Hospital-specific 30-day all-cause RSMR. RESULTS At the patient level, the odds of dying within 30 days of admission if treated at a hospital 1 SD above the national average relative to that if treated at a hospital 1 SD below the national average were 1.63 (95% CI, 1.60-1.65) in 1995 and 1.56 (95% CI, 1.53-1.60) in 2006. In terms of hospital-specific RSMRs, a decrease from 18.8% in 1995 to 15.8% in 2006 was observed (odds ratio, 0.76; 95% CI, 0.75-0.77). A reduction in between-hospital heterogeneity in the RSMRs was also observed: the coefficient of variation decreased from 11.2% in 1995 to 10.8%, the interquartile range from 2.8% to 2.1%, and the between-hospital variance from 4.4% to 2.9%. CONCLUSION Between 1995 and 2006, the risk-standardized hospital mortality rate for Medicare patients discharged with AMI showed a significant decrease, as did between-hospital variation.

Relationship Between Hospital Readmission and Mortality Rates for Patients Hospitalized With Acute Myocardial Infarction, Heart Failure, or Pneumonia

IMPORTANCE The Centers for Medicare & Medicaid Services publicly reports hospital 30-day, all-cause, risk-standardized mortality rates (RSMRs) and 30-day, all-cause, risk-standardized readmission rates (RSRRs) for acute myocardial infarction, heart failure, and pneumonia. The evaluation of hospital performance as measured by RSMRs and RSRRs has not been well characterized. OBJECTIVE To determine the relationship between hospital RSMRs and RSRRs overall and within subgroups defined by hospital characteristics. DESIGN, SETTING, AND PARTICIPANTS We studied Medicare fee-for-service beneficiaries discharged with acute myocardial infarction, heart failure, or pneumonia between July 1, 2005, and June 30, 2008 (4506 hospitals for acute myocardial infarction, 4767 hospitals for heart failure, and 4811 hospitals for pneumonia). We quantified the correlation between hospital RSMRs and RSRRs using weighted linear correlation; evaluated correlations in groups defined by hospital characteristics; and determined the proportion of hospitals with better and worse performance on both measures. MAIN OUTCOME MEASURES Hospital 30-day RSMRs and RSRRs. RESULTS Mean RSMRs and RSRRs, respectively, were 16.60% and 19.94% for acute myocardial infarction, 11.17% and 24.56% for heart failure, and 11.64% and 18.22% for pneumonia. The correlations between RSMRs and RSRRs were 0.03 (95% CI, -0.002 to 0.06) for acute myocardial infarction, -0.17 (95% CI, -0.20 to -0.14) for heart failure, and 0.002 (95% CI, -0.03 to 0.03) for pneumonia. The results were similar for subgroups defined by hospital characteristics. Although there was a significant negative linear relationship between RSMRs and RSRRs for heart failure, the shared variance between them was only 2.9% (r2 = 0.029), with the correlation most prominent for hospitals with RSMR <11%. CONCLUSION AND RELEVANCE Risk-standardized mortality rates and readmission rates were not associated for patients admitted with an acute myocardial infarction or pneumonia and were only weakly associated, within a certain range, for patients admitted with heart failure.