The United States had by far the highest rate of 30-day readmission after a discharge diagnosis of ST-elevation myocardial infarction in an international study of 17 Western nations, published in the Jan. 4 issue of JAMA.
Even though the readmission rate varied greatly from one country to the next, America’s 14.5% rate of readmission within 30 days was at least one-third higher than that of the other 16 countries, said Dr. Robb D. Kociol of Duke Clinical Research Institute, Durham, N.C., and his associates.
This discrepancy appeared to be related to patients’ hospital length of stay, which was significantly shorter in the United States than in all the other countries, they noted.
Dr. Kociol and his colleagues studied 30-day readmission rates because "high" rates are increasingly used as an indicator of both poor quality of care and unnecessarily high health care costs. Researchers are trying to identify predictors of readmission in hopes of lowering these rates.
The investigators performed a post hoc analysis of data from an international clinical trial of acute STEMI – Assessment of Pexelizumab in Acute Myocardial Infarction – that had been conducted at 296 sites between 2004 and 2006. There were 5,571 study subjects who survived to hospital discharge, and 631 (11.3%) of them were readmitted within 30 days.
The rate of early readmission was 14.5% within the United States, compared with 9.9% outside the United States. This represents a 68% increase in the risk of readmission for U.S. patients, Dr. Kociol and his associates said (JAMA 2011;307:66-74).
"Higher readmission rates in the U.S. may be an adverse effect of the short length-of-stay practice."
When subjects who were readmitted for elective revascularization procedures were excluded from the analysis, the rate of readmission was 10.5% in the United States, compared with 7.7% outside this country.
Several countries had significantly lower odds of 30-day readmission than the United States, including Italy, Germany, Canada, Portugal, the Netherlands, and the Czech Republic. The other countries participating in the MI study were Australia, Austria, Belgium, Switzerland, Denmark, Spain, France, New Zealand, Poland, and Sweden.
In a further analysis of the data, increased disease severity (as measured by the number of involved vessels), a high baseline heart rate, and high-risk changes on ECG were all important predictors of early readmission. However, residence in the United States was the strongest predictor of 30-day readmission for any cause, they added.
Several predictive factors were comparable between the United States and the other countries, including patient age, sex, and comorbidities. Rates of appropriate discharge prescriptions for medications such as aspirin, ticlopidine, clopidogrel, beta-blockers, and statins also were similar.
One factor that stood out as different was hospital length of stay. "Perhaps the most intriguing finding" of this study was that length of stay showed an inverse correlation with risk of readmission. Each 1-day increase in length of stay was associated with a 17% reduction in risk of readmission.
The United States had the shortest hospitalizations. Length of stay was 3 days or fewer for two-thirds of U.S. patients but for only 16% of non-U.S. patients. And only 16.6% of U.S. patients were hospitalized for 6 days or longer, compared with 54% of patients outside the U.S.
"These data raise the possibility that higher readmission rates in the U.S. may be an adverse effect of the short length-of-stay practice," the investigators noted.
Another system-related difference between the United States and the other countries in this study is that most of them have near-universal health care coverage for all citizens, whether through a state-run system, private compulsory health insurance, or a combination of the two. This may allow people in the other countries to obtain faster and easier access to post-discharge follow-up with a primary caregiver, heading off readmission, Dr. Kociol and his colleagues added.
This study was supported by the Duke Clinical Research Institute. The original MI study was funded by Procter & Gamble, Alexion, and the American Heart Association Pharmaceutical Roundtable.