"Virtual" clinical trials: case control experiments utilizing a health services research workstation.

We created an interface to a growing repository of clinical and administrative information to facilitate the design and execution of case-control experiments. The system enables knowledgeable users to generate and test hypotheses regarding associations among diseases and outcomes. The intuitive interface allows the user to specify criteria for selecting cases and defining putative risks. The repository contains comprehensive administrative and selected clinical information on all ambulatory and emergency department visits as well as hospital admissions since 1994. We tested the workstation's ability to determine relationships between outpatient diagnoses including hypertension, osteoarthritis and hypercholesterolemia with the occurrence of admissions for stroke and myocardial infarction and achieved results consistent with published studies. Successful implementation of this Health Services Research Workstation will allow "virtual" clinical trials to validate the results of formal clinical trials on a local population and may provide meaningful analyses of data when formal clinical trials are not feasible.