Preference for Virtual Colonoscopy Scan (VC) over optical Colonoscopy

By Eric Barnes, staff writer

Patients undergoing virtual colonoscopy experience less pain and discomfort and more overall satisfaction than those undergoing conventional colonoscopy, a recent research study has found.

Months after the exam, however, perceptions of the experience evened out. The new analysis of the multicenter U.K. Special Interest Group in Gastrointestinal and Abdominal Radiology (SIGGAR) trial differed in key ways from previous patient-satisfaction studies, which have generally favored virtual colonoscopy (also known as CT colonography or CTC) for its greater patient comfort. For one thing, the current screening trial randomized exam selections, with patients scheduled to receive one exam or the other but not both. In addition, this study included a three-month follow-up interview to assess patients’ longer-term views. “We found small but significant and consistent advantages favoring CT colonography, which was also associated with fewer post-test problems,” wrote study authors Christian von Wagner, PhD; Dr. Steve Halligan; and others from the University College London, along with colleagues from Imperial College London and Birmingham University.

CTC’s perceived advantages disappeared over time, however. “The two tests are comparable (and highly favorable) in terms of longer-term consequences,” the group wrote in a study published online March 21 in Radiology. The researchers sought to diverge from previous studies comparing patient preferences for the screening exams. “Studies of acceptability have typically been nonrandomized, often with within-subject comparisons with CT colonography given first, followed immediately by colonoscopy,” von Wagner and colleagues wrote. “Although convenient, such designs may miss aspects of experience. For example, in daily practice, some patients undergoing CT colonography or colonoscopy are referred for further colonic investigations (usually after CT colonography for lesion confirmation and biopsy). Patients may view referral negatively.”

Two exams, one per patient A total of 547 patients, all 55 years or older, with symptoms indicating colorectal cancer (change in bowel habit, anemia, bleeding, etc.) were recruited between 2004 and 2007 at 21 U.K. hospitals and referred for evaluation of the entire colon. They were randomly assigned at a 2-to-1 ratio to undergo either colonoscopy (n = 362) or CTC (n = 185). All patients followed dietary restrictions and underwent full-bowel purgation. For CTC, most of the centers used sodium picosulphate/magnesium citrate, one used macrogol, and one used sodium meglumine diatrizoate. All CTC exams were preceded by bowel insufflation with room air or CO2 and IV administration of the antispasmolytic agent hyoscine-N-butylbromide unless contraindicated.

Fourteen centers used automated insufflation of CO2 (ProtoCO2l, Bracco Diagnostics), six used room air, and one used air and CO2 about equally, the authors wrote. Video-assisted optical colonoscopy was performed by 227 practitioners using endoscopes, with sedation in approximately 80% of exams and analgesia in 87%, von Wagner and colleagues wrote. The post-test questionnaires assessed bowel preparation and satisfaction with the exam. Eight potential adverse effects — abdominal pain and/or cramps, nausea and/or vomiting, faint feeling or dizziness, gas, soreness, soiling, sleep difficulties, and anxiety — were evaluated on a severity score of 1 to 4. Three months later, the follow-up questionnaires assessed how and when patients received their results, psychologic consequences of the test, and feelings about a second exam if patients were referred for one.

Satisfaction edge for VC Post-test results Immediately after the exam, patients reported the following: Those undergoing colonoscopy were less satisfied with the test (median score 61, interquartile range [IQR]: 55-67) than those who received CTC (median score 64, IQR: 58-70, p = 0.008). Colonoscopy patients were significantly more worried (median score 16, IQR: 12-21) than CTC patients (median score 15, IQR: 9-19, p = 0.007). Colonoscopy patients experienced more discomfort (median score 39, IQR: 29-51) than CTC patients (median score 35, IQR: 24-44). Colonoscopy patients experienced more adverse events such as dizziness or feeling faint (82 of 246) than CTC patients (28 of 122, p = 0.39) Three-month follow-up: There were no differences in three-month psychological consequences of diagnosis, except a trend toward a difference in negative effect (p = 0.05), with patients undergoing CTC reporting less intense negative experiences.

Patients undergoing colonoscopy were significantly more likely to receive their results on the same day (65%, versus 17% for CTC), and colonoscopy patients were also more likely to receive results in a face-to-face conversation with the provider (85%, versus 50% for CTC). Logically, colonoscopy patients were more satisfied with the way the results were conveyed. Substantially more of the patients were referred for additional exams after CTC compared to conventional colonoscopy, which is both diagnostic and therapeutic when used to remove polyps. Thirty-five patients referred after CTC were sent to colonoscopy or flexible sigmoidoscopy.

Among 230 patients who underwent colonoscopy, six (3%) were referred subsequently for CT colonography, four (2%) for barium enema, four (2%) for flexible sigmoidoscopy, two (1%) for repeat colonoscopy, and one for surgery. Among responding patients referred for colonic follow-up testing, two (25%) of eight patients in the colonoscopy group reported that they “minded” being referred, compared with nine (39%) of 23 responding patients referred after CTC, von Wagner and colleagues stated. Study limitations include the possibility of patients having preconceived notions about the exams, and the fact that they rated them without comprehensive knowledge of their sensitivity. In addition, there were differences in how the exams were performed in the 21 centers, including variations in bowel preparation, sedation and/or analgesia, and gas insufflation, which may have influenced patients’ opinions, according to the authors.

The fact that all of the patients were symptomatic also merits consideration, explained Dr. Steve Halligan in an email to”Symptomatic patients are a complex group — the physician is faced with a patient who is complaining of something,” Halligan noted. “If a test is normal and the patient still has symptoms, then the clinician may choose to continue chasing the symptoms with another test, even if the first test is normal or only shows a small polyp, etc.” SIGGAR was a pragmatic trial inasmuch as it “looked at what happens when tests are implemented in normal daily clinical practice versus strictured by all sorts of referral criteria specific to a research study,” he added. “The situation is much cleaner for a screening study — we are looking for a limited pathology set and clear criteria for onward referral.”

As a result, the effects of the higher referral rate in this symptomatic cohort can’t readily be extrapolated to a study of asymptomatic patients. For asymptomatic individuals undergoing screening CTC, the referral rate to colonoscopy would be expected to range from approximately 8% to 12% of participants, far lower than the 33% referred in this analysis. As a result, far fewer screening patients would be expected to be dissatisfied as a result of having been referred for a second exam. Overall the findings suggest that CTC is more immediately acceptable to patients than colonoscopy, but postprocedural differences in the way results are delivered favor colonoscopy, the authors concluded.

Psychological outcomes were comparable between the two tests. “When making decisions to refer symptomatic patients, the clinical and administrative advantages of colonoscopy should be balanced against the superior acceptability of CT colonography,” von Wagner and colleagues wrote.