Time Trends in Colonoscopy Volume in the United States from 2002 to 2007

Abstract

Background: In 2001, Medicare instituted reimbursement for average-risk screening colonoscopy. Several studies have reported an increase in colonoscopy volume in the period immediately following this change in Medicare policy. However, it is unknown if colonoscopy volume has continued to increase in the ensuing years. The purpose of this study was to quantify changes in colonoscopy volume between 2002 and 2007. Methods: We performed a longitudinal retrospective cohort study using endoscopist- and procedure-level data from the Clinical Outcomes Research Initiative (CORI) database. All colonoscopies performed between 2002 and 2007 were eligible for inclusion in the analysis. Endoscopists performing fewer than 100 colonoscopies in any year of analysis were excluded. Data were extracted on annual colonoscopy volume for each endoscopist as well as the indication for each colonoscopy (average-risk screening or surveillance). To fully account for the multiple data points (colonoscopies) within each endoscopist (panel data), we used generalized estimating equations (GEE) rather than simple linear regression (aggregate data) to compare annual changes in colonoscopy volume. Results: 142 endoscopists performed 481,883 procedures during the time period and were included in the analysis. 85% of procedures were performed in a community/HMO setting, and 9% and 5% were performed in a VA/Military and non-VA academic setting, respectively. Common indications for colonoscopy were average-risk screening (24% of procedures) and surveillance (21%). Mean colonoscopy volume per endoscopist gradually increased between 2002 (476 colonoscopies per year (CPY)) and 2006 (616 CPY), but then decreased slightly to 574 CPY in 2007 (p<0.0001 for each year compared to 2002). In subgroup analyses by indication (screening and surveillance), a similar relationship between colonoscopy volume and year of exam was noted (Table). Conclusions: Screening, surveillance, and overall colonoscopy volume has continued to increase in the years following the enactment of Medicare reimbursement for average-risk screening. Pending analyses of these data will examine the impact of this ongoing increase in colonoscopy demand on colonoscopy procedure time and polyp detection rates (colonoscopy quality markers).