US geographic distribution of rt-PA utilization by hospital for acute ischemic stroke

Previously, we have estimated US national rates of recombinant tissue plasminogen activator (rt-PA) use to be 1.8% to 3.0% of all ischemic stroke patients. However, we hypothesized that the rate of rt-PA use may vary widely depending on regional variation, and that a large percentage of the US population likely does not have access to hospitals using rt-PA regularly. We describe the US geographic distribution of hospitals using rt-PA for acute ischemic stroke.

This analysis used the MEDPAR database, which is a claims-based dataset that contains every fee-for-service Medicare-eligible hospital discharge in the US. Cases potentially eligible for rt-PA treatment based on diagnosis were defined as those with a hospital DRG code of 14, 15, or 559, and that also had an ICD-9 code of 433, 434, or 436. Thrombolysis use was defined as an ICD-9 code of 99.1. Study interval was July 1, 2005 to June 30, 2007. Hospital locations were mapped using ArcView software; population densities and regions of the US are based on US Census 2000.

There were 4750 hospitals in the MEDPAR database, which included 495 186 ischemic stroke admissions during the study period. Of these hospitals, 64% had no reported treatments with rt-PA for ischemic stroke, and 0.9% reported >10% treatment rates within the MEDPAR dataset. Bed size, rural or underserved designation, and population density were significantly associated with reported rt-PA treatment rates, and remained significant in the multivariable regression. Approximately 162 million US citizens reside in counties containing a hospital reporting a >or=2.4% treatment rate within the MEDPAR dataset.

We report the first description of US hospital rt-PA treatment rates by hospital. Unfortunately, we found that 64% of US hospitals did not report giving rt-PA at all within the MEDPAR database within a 2-year period. These tended to be hospitals that were smaller (average bed size of 95), located in less densely populated areas, or located in the South or Midwest. In addition, 40% of the US population resides in counties without a hospital that administered rt-PA to at least 2.4% of ischemic stroke patients, although distinguishing transferred patients is problematic within administrative datasets. Such national-based resource-utilization data is important for planning at the local and national level, especially for such initiatives as telemedicine, to reach underserved areas.