The effect of an on-site radiology facility on radiologic utilization in family practice.

Family physicians around the world are increasing their use of diagnostic x-ray examinations at a time of controversy about radiologic overutilization. To explore the role of accessibility in utilization, a study was undertaken testing the hypothesis that on-site radiology facilities are an important determinant of usage. Using a historical cohort design with chart review, rates in selected groups of patients were compared between two teaching family medicine centers, one with an on-site radiology service and one without. After controlling for confounding variables, patients with chest-related diagnoses were 2.4 times more likely (P less than .05) to have a chest film in the presence of on-site facilities. Rates for the off-site examination, upper gastrointestinal series, in patients with abdominal-related diagnoses were similar (relative risk 1.34, P greater than .5) at both centers. Higher usage brought no short-term clinical benefit. It was also observed that residents overinterpreted one quarter of chest films when compared with radiologists' reports.