Virtual colon scans bring big benefits but face big hurdles

Virtual colonoscopy has much to recommend it, including charges about half of those for optical colonoscopy. But it faces significant hurdles before it becomes a major part of the nation's colon cancer screening program, presenters said during an educational session Friday.

In all but a few instances, Medicare payment policies have kept virtual colonoscopy (VC) in the background, leaving the 80 million people in the 50 and over screening category with little choice but to seek optical colon (OC) scans. CMS sometimes allows virtual scans in instances when optical scans fail, but VC's use in screening is universally rejected except by some private payers.

Some practices collecting private payments for virtual scans are charging about $900 for the VC service compared with $2400 for optical scans, said copresenter Dr. Bruce Reiner, director of research at the Baltimore VA Medical Center. Medicare, when it does pay for a diagnostic virtual scan, allows $600 compared with $1100 for an optical scan.

The virtual colon scan is minimally invasive, can identify extracolonic findings, and has a lower risk of morbidity, usually bowel perforation, than optical colonoscopy, Reiner said.

VC scan times are shorter (14.1 minutes versus 31.5 minutes for OC) and require less of a time commitment by the patient, who is usually sedated with OC and must take a day off from work to recover, said copresenter Allyson Conway Mortati, a virtual colonoscopy product manager for E-Z-EM.

Where VC has run into problems is in the realm of clinical data. Two papers are commonly cited: a best-case 2003 paper by Pickhardt et al that found VC and OC equivalent in spotting polyps 6 mm or larger, and a worst-case 2004 paper by Cotton et al that gave VC only a 55% sensitivity in detecting polyps 10 mm or larger. The Pickhardt study used optimized screening techniques, including 3D interpretation, rigorous bowel cleansing, and a relatively healthy patient base, Mortati said. The Cotton study used older 2000-2001 data and less refined interpretive techniques.

VC advocates have pinned their hopes on a clinical trial of 2000 patients at 15 centers that will compare the two modalities. The American College of Radiology Imaging Network is sponsoring the trial.

If the results are good, VC will have to prove its value on an economic basis. It may stand a good chance there as well, based on information Reiner presented. Quantitative analysis has generally been confined to the gastroenterology literature, which for the most part concludes that the higher the chance of finding polyps, the greater reason to go to OC in the first place.

Consensus holds that for VC to be cost-effective, it must be priced at 60% or less of the charges for OC, Reiner said. Based on current charges, VC more than meets that threshold.

One solution has been found already in Wisconsin where Dr. Perry Pickhardt, an associate professor of abdominal imaging at the University of Wisconsin, Madison, has worked with gastroenterologists in a cooperative approach to screening, Reiner said. They have managed to win some payment support from managed care organizations in the area.

Factors that made the collaboration possible included long waits for OC and a need to increase the frequency of screening, Reiner said.