CTC tops colonoscopy, but author/journal bias may be a factor

A systematic review of the available literature on patient preferences for CT colonography (CTC) versus colonoscopy has shown that while the majority of studies score CTC as the preferred test, results varied based on patient type and the publishing journal’s specialty focus, according to an article published online in the Journal of General Internal Medicine.

Review authors Otto S. Lin, MD, of Virginia Mason Medical Center in Seattle, and colleagues examined published studies, abstracts and book chapters that were published from 1995 through February 2012. Studies could feature either prospective or retrospective enrollment of diagnostic or screening patients who had undergone both CTC and colonoscopy and reported their preference.

A total of 23 studies, featuring 5,616 subjects, met the review’s inclusion criteria. Lin et al reported that in 16 of these studies, patients preferred CTC over colonoscopy, while colonoscopy was preferred in three studies.

Because of the various study designs, the authors did not calculate an overall pooled preference, but a stratified analysis was conducted to tease out the effect of certain variables, such as CTC technique, procedure indication and the type of journal in which the study was published.

“Because acceptance and preference are ‘soft’ measures, they are prone to bias,” explained the authors. “This is reflected by the differences seen when studies are stratified by journal type or lead author specialty.” Studies published in radiology journals or by radiology authors demonstrated a stronger preference for CTC compared with studies in gastroenterology journals or from gastroenterology authors. Studies in general medicine journals were less likely to show a preference for CTC compared with radiology journals.

Symptomatic patients had no preference, but screening patients preferred CTC, according to the results.

Lin and colleagues noted that methodological differences may explain some of the variation in results between studies from differing journal and specialty types. Six out of 11 radiology studies included screening cohorts, while only two out of 11 gastroenterology or general medicine studies included a screening cohort. In addition, the three studies using “low prep” CTC regimens—which can feature laxative-free bowel preparation—were all conducted by radiology authors.

“Previous studies have consistently shown that bowel preparation is the worst part of the colonoscopy experience,” wrote the authors. “However, it must be kept in mind that in clinical practice, ‘low-prep’ regimens would necessitate a second, fuller bowel preparation for colonoscopy if pathology (e.g. polyp) is discovered; this may impact the preference of some patients.”

While CTC is preferred in general, the authors pointed to a couple barriers standing in the way of wider CTC use, including inadequate insurance coverage for the procedure. Even if CTC reimbursement spreads, Lin and colleagues suggested that closer logistical cooperation between radiology and gastroenterology departments would be needed to ensure same-day colonoscopy after a positive CTC exam.