Regional differences in use of endoscopic ultrasonography in Ontario: a population-based retrospective cohort study.

BACKGROUND:Endoscopic ultrasonography is a safe and accurate modality for evaluating and managing hepatobiliary and gastrointestinal conditions (malignant and nonmalignant); its use is increasing. The aim of this study was to describe regional trends in the use of endoscopic ultrasonography in Ontario. METHODS:We conducted a population-based retrospective cohort study using health administrative databases. We identified all patients who underwent an endoscopic ultrasound procedure in Ontario from 2003 to 2011 using physician billing data. Patient, physician and institution characteristics were examined. The primary outcome was use of endoscopic ultrasonography. RESULTS:We identified 9076 endoscopic ultrasound procedures performed in 8001 patients (3858 women [48.2%]; median patient age at first procedure 59 years). A total of 3066 procedures (33.8%) involved fine-needle aspiration. Use of endoscopic ultrasonography increased 17-fold over the study period. In 2011, people living in the health region with the highest rate of use of endoscopic ultrasonography were more than 4 times more likely to undergo the procedure than people living in the health region with the lowest rate of use (standardized rate 61.6 v. 12.9 per 100 000). About 7 in 10 endoscopic ultrasound procedures were performed in an academic institution or regional cancer centre. All 17 endoscopists performing endoscopic ultrasonography during the study period practised in urban areas. INTERPRETATION:Although the use of endoscopic ultrasonography increased over time in Ontario, there were marked regional differences in use. Provincial needs- and evidence-based initiatives may be needed to narrow the regional gaps in provision of endoscopic ultrasound services in the province.