LOS ANGELES — Establishment of a screening program using virtual colonoscopy did not lead to a decrease in the number of standard optical colonoscopies performed within 14 months of its introduction, Dr. Darren C. Schwartz reported at the annual Digestive Disease Week.
Only a small proportion of patients who underwent virtual colonoscopy were subsequently referred for optical colonoscopy with polypectomy, said Dr. Schwartz, a fellow at the University of Wisconsin, Madison.
Contrary to the researchers' initial hypothesis, there was no observable shift in the purpose of optical colonoscopy referrals from screening to therapeutic interventions such as polypectomy.
Dr. Schwartz and his colleagues measured the impact of primary screening virtual colonoscopy on the demand for optical colonoscopy at the University of Wisconsin Medical Center. This project was feasible because in 2004, third-party payers in Wisconsin agreed to pay for primary screening virtual colonoscopy for patients at average risk for colorectal cancer.
All optical colonoscopy procedures were performed by 10 university attending gastroenterologists, and all virtual colonoscopy procedures were performed by three attending radiologists at the same university-based endoscopy unit.
The investigators collected virtual colonoscopy and optical colonoscopy referral data and information about the number and type of procedures prospectively. The relevant time periods were the 3 months before the introduction of screening virtual colonoscopy (T1), the period from 3 months before to 5 months after virtual colonoscopy became available (T2), and the 14-month period after introduction of virtual colonoscopy (T3).
The investigators also looked at the period 6–14 months after virtual colonoscopy screening was initiated (T4) because they thought there would be an initial increase in virtual colonoscopy productivity during the first 6 months, followed by a “steady state” level of productivity.
End points included monthly referrals for virtual colonoscopy and optical colonoscopy, monthly number of virtual colonoscopies actually performed, and monthly numbers of screening optical colonoscopies, total optical colonoscopies, and optical colonoscopies with polypectomy.
Monthly referrals for screening optical colonoscopy fell from a mean of 255 (T1) to 218 (T3) after institution of virtual colonoscopy screening, but this decrease was not significant. The total number of optical colonoscopies and the number of screening optical colonoscopies actually performed per month also did not change significantly. The mean percentage of optical colonoscopies with polypectomy remained essentially constant during all study periods, ranging from 40.5% for T2 to 42.9% for T4.
Of the patients who had screening virtual colonoscopies during study period T4 (mean of 120 per month), 15.1% had polyps detected and 7.0% (8.4 per month) were referred for optical colonoscopy with polypectomy. In addition, 136 patients initially referred for optical colonoscopy subsequently opted for virtual colonoscopy between T2 and T4.
Dr. Schwartz reported no relevant financial relationships.