Outcomes of acute myocardial infarction patients admitted to different hospitals.

OR = odds ratio; CI = confidence interval; HR = hazard ratio.Note: The analyses of length of stay and 30-day readmissions excluded patients who died in hospital or were transferred to another acute care hospital after admission. The analyses of 30-day readmissions also excluded readmissions for rehabilitations and were limited to patients admitted before November 30, 2008.*Multivariate generalized linear (for length of stay), logistic (for readmissions and 30-day mortality) and Cox proportional hazard (for 1-year mortality) models adjusted for patient age, gender, race, median household income, high school graduation rate, tobacco use, individual medical comorbidities (congestive heart failure, cardiac arrhythmias, valvular disease, pulmonary circulation disorders, peripheral vascular disorders, hypertension, paralysis, other neurological disorders, chronic pulmonary disease, diabetes, hypothyroidism, renal failure, liver disease, peptic ulcer disease excluding bleeding, lymphoma, metastatic cancer, solid tumor without metastasis, rheumatoid arthritis, coagulopathy, obesity, weight loss, fluid and electrolyte disorders, blood loss anemia, and deficiency anemia), and hospital characteristics (including number of beds, profit status, rural vs. urban location, teaching status, and nurse staffing ratio).**Low-quality hospitals were defined as those in the bottom 10% rankings of the composite quality score, medium-quality hospitals in the middle 80%, and high-quality hospitals in the top 10% rankings of the composite quality score.