**7. Patient preferences**

When asked if they would prefer CTC or OC, patients more often prefer CTC [102]. In one study, 696 asymptomatic patients at high risk for colorectal cancer screening underwent both CTC and OC [103]. Patients were asked using standardized forms about preparation inconvenience and discomfort, examination discomfort and examination preference. Over‐ all, patients preferred CTC to OC (72.3% vs. 5.1%; P <0.001). Reported discomfort however, was similar for CTC and OC (P = 0.63). In another study that evaluated patients with a histo‐ ry of diverticulitis, 74% preferred CTC preferred over OC [71]. Patients found colonoscopy more uncomfortable (p < 0.03), more painful (p < 0.001), and more difficult (p < 0.01) than CTC [71].

Other studies conflict with those mentioned above. Even though CTC is a less invasive alter‐ native than OC, procedural pain is not uncommon. In several studies, the pain associated with CTC was higher than that associated with OC, albeit there is no sedation given for the former test [104]. Using a time-trade off technique, 295 patients reported statistically more pain and discomfort after CTC and showed preference for optical colonoscopy [105]. The pain during CTC however, is usually not so severe as to abort the test [33].

In a well-designed study, 111 patients underwent CTC followed immediately by OC [15]. The preference for either examination was evaluated after completion of both examina‐ tions. Of the 68 patients who favored one examination, 56 [82%) preferred CTC (P < 0.00001). CTC was regarded as "not painful" by 62 (57%) of 108 patients compared with 28 (26%) for colonoscopy [15].

Intuitively we may believe that CTC, being a noninvasive test, would be preferred to OC by most patients. However, when the risks of finding lesions that require follow-up and other factors are taken into account, patient preferences may change. In one study, OC was preferred over CTC as the need for a follow-up test increased, as the likelihood of missing cancers or polyps increased, and as the cost for CTC increased (the odds rato of preferring CTC to OC ranged from 0.65 to 0.80)[106]. Therefore, an informed decision re‐ garding CTC vs. OC should include a discussion of the benefits, risks, costs and associat‐ ed uncertainties of the tests. In summary, patients usually prefer CTC to OC but the preference is most likely dependent on a number of other factors such as insurance cover‐ age, type of sedation used locally for OC, and the risk of finding a significant polyp on CTC thereby requiring a follow-up OC.
