30-day risk-standardized mortality and readmission rates after ischemic stroke in critical access hospitals

BACKGROUND AND PURPOSE-: The critical access hospital (CAH) designation was established to provide rural residents with local access to emergency and inpatient care. CAHs, however, have poorer short-term outcomes for pneumonia, heart failure, and myocardial infarction compared with other hospitals. We assessed whether 30-day risk-standardized mortality rates (RSMRs) and risk-standardized readmission rates (RSRRs) after ischemic stroke differ between CAHs and non-CAHs. METHODS-: The study included all fee-for-service Medicare beneficiaries 65 years of age or older with a primary discharge diagnosis of ischemic stroke (International Classification of Diseases, 9th revision codes 433, 434, 436) in 2006. Hierarchical generalized linear models calculated hospital-level RSMRs and RSRRs, adjusting for patient demographics, medical history, and comorbid conditions. Non-CAHs were categorized by hospital volume quartiles and the RSMR and RSRR posterior probabilities in comparison with CAHs were determined using linear regression with Markov chain Monte Carlo simulation. RESULTS-: There were 10 267 ischemic stroke discharges from 1165 CAHs and 300 114 discharges from 3381 non-CAHs. The RSMRs of CAHs were higher than non-CAHs (11.9%±1.4% vs 10.9%±1.7%; P<0.001), but the RSRRs were comparable (13.7%±0.6% vs 13.7%±1.4%; P=0.3). The RSMRs for the 2 higher volume quartiles of non-CAHs were lower than CAHs (posterior probability of RSMRs higher than CAHs=0.007 for quartile 3; P<0.001 for quartile 4), but there were no differences for lower volume hospitals; RSRRs did not vary by annual hospital volume. CONCLUSIONS-: CAHs had higher RSMRs compared with non-CAHs, but readmission rates were similar. The observed differences may be partly explained by patient characteristics and annual hospital volume.