Research Brief 44:
Washington Inpatient Atlas Project (WIAP)

Concerns about the increasing cost of health care have led to questions about the appropriate quality, accessibility, and utilization of healthcare resources. The most comprehensive research to date on the geographic variation of healthcare, the Dartmouth Atlas of Health Care, revealed substantial differences in the access to and usage of healthcare resources, both across the country and even within single cities, including wide variation in the use of many major medical procedures. The substantial geographic variation in the use of medical treatments and hospital resources suggests that decisions about health care are not always based on solid scientific evidence. They may be based on the availability of resources, as well as regional trends and consensus.

Research Brief Series

Following an introductory document, there is a series of research briefs, each of which could be read as a stand-alone document. Each of these describes the geographic and historical variation in the usage rate of a specific inpatient surgical procedure in Washington State. Each brief includes four charts:

the statewide rates by sex and age bracket over the period 1990-2005,
the statewide rates for each year from 1990-2005 adjusted for age and sex with confidence intervals,
the regional rates adjusted for age and sex in 2005 with confidence intervals, and
the regional rates adjusted for age and sex for each year in the period 1990-2005.

There are many possible explanations for the observed variations. These studies do not make any conclusions as to why the variations exist. The purpose is to display them and hopefully to stimulate discussion.