Geographic patterns in recurrent ischemic stroke

Background. Over 185,000 recurrent strokes occur in the United States each year. The aims of this dissertation are to identify whether there are geographic patterns in recurrent stroke within the first year after an incident stroke, how these patterns may have changed over time and whether healthcare availability and accessibility are associated with these recurrent stroke patterns.;Methods. Recurrent stroke rates for ischemic stroke were calculated for 1-year following hospital discharge for stroke by county for all fee-for-service Medicare beneficiaries from 1994 to 2002. For the first study, we calculated rates for 2000 to 2002. The rates were then standardized, smoothed, and mapped. A Bayesian conditional autoregressive model risk-adjusted for patient characteristics. In the second study, we examined whether patterns in recurrent stroke have changed from 1994 to 2002. To achieve this a Bayesian spatio-temporal Poisson model was used to determine county-specific risk-adjusted recurrent stroke rates over time. For the third study, we developed county measures of socioeconomic status and indicators of healthcare availability and accessibility. These measures were then included as covariates in a Bayesian conditional autoregressive model of recurrence rates from 2000 to 2002.;Results. We identified substantial geographic variation in the rates of recurrent ischemic stroke by county across the United States. These patterns persisted even after adjustment for individual patient characteristics. Recurrent stroke rates have declined 5% in the US from 1994-1996 to 2000-2002, however temporal patterns varied markedly by geographic region. Although counties with fewer physicians had higher recurrent stroke rates, after risk-adjustment there was no association between our selected measures of healthcare availability and accessibility and recurrent stroke hospitalization rates.;Conclusions. One-year recurrent stroke hospitalization rates vary substantially across the United States. Over the past decade national recurrent stroke rates have decreased by almost 5%; however these temporal patterns vary by region, with areas of the west and northwest experiencing increasing recurrent stroke rates. These geographic patterns cannot be explained by county differences in patient characteristics or healthcare availability and accessibility.