PITTSBURGH — Hospitals with low adherence to acute MI process measures have higher 30-day mortality rates than do other U.S. hospitals, even after adjustment for differences in patient populations.
Recent studies have shown significant improvements in adherence to acute MI process measures—particularly aspirin and β-blockers and ACE inhibitors for left-ventricular systolic dysfunction—but little is known about the hospitals with consistently poor adherence or the relationship between poor adherence and outcomes.
Dr. Ioana Popescu of the department of internal medicine at the University of Iowa, Iowa City, and associates calculated a composite acute MI compliance score for 2,761 hospitals that reported acute MI process measures for at least 25 acute MI cases a year to the Centers for Medicare and Medicaid Services' Hospital Quality Alliance database in 2004–2006. The number of hospitals—2,761—represents 63% of U.S. hospitals treating acute MI patients.
The hospitals were categorized as low-performing (lowest decile for every study year), high-performing (highest decile), and intermediate-performing (all other), Dr. Popescu reported at the annual meeting of the Society of General Internal Medicine.
Risk-adjusted mortality was calculated as the observed or predicted mortality multiplied by the mean overall population mortality rate, using the records of 208,080 Medicare beneficiaries admitted with acute MI in 2005. The 30-day predicted mortality was estimated using models controlling for patient demographics, comorbidity, and patient clustering within hospitals.
Mean compliance for the five widely reported acute MI process measures was 68% for the 105 low-performing hospitals, 92% for the 2,493 intermediate performers, and 99% for the 163 high-performing hospitals.
Compared with high-performers, low performers were significantly less likely to be teaching hospitals or in an urban location. Low performers were more likely “safety net” hospitals and to be for-profit institutions. The proportion of uncompensated care was significantly greater at low-performing hospitals, whereas staffing ratio, acute MI volume, revascularization, and bed count rates were lower.
Patients at low-performing hospitals were slightly older (80 vs. 79 years), and more likely to be black (9% vs. 4%), female (56% vs. 48%), have lower incomes ($33,739 vs. $46,698), and more comorbidities than those at high-performing institutions.
Mean observed 30-day mortality after acute MI was 26% at the low-performers, 19% at intermediate hospitals, and 15% at the high performers. Even after controlling for differences in patient characteristics, the mean 30-day risk-adjusted mortality rate was significantly greater for low performers, at 19%, versus 16% for the intermediate and 15% for the high performers.