Seasonal Variation in 30-Day Mortality After Stroke

Teaching Versus Nonteaching Hospitals

STROKEAHA: January 8, 2013

Background and Purpose—A systematic review found an association between the July start of internships and residencies and higher mortality rates for hospitalized patients, but data related to stroke are limited. We assessed seasonal variations in 30-day risk-adjusted mortality rates (RAMRs) after ischemic stroke by hospital teaching status.

Methods—The analysis included all fee-for-service Medicare beneficiaries aged ≥65 years with a primary discharge diagnosis of ischemic stroke (International Classification of Diseases9th revision, codes 433, 434, and 436) from 1999 to 2006. Hierarchical linear regression models calculated RAMRs, adjusting for patient demographics and comorbidities. Annual data were combined and reconstructed for time series analyses; RAMRs were calculated for each month. Structural models compared monthly seasonal patterns stratified by hospital teaching status. Read More