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Background and Study Aims: Novel imaging techniques need to be evaluated for their ability to improve the detection of polyps. Critical appraisal of reported studies reveals remarkable differences in study designs, despite their similar objectives. The aim of the current study was to compare frequently used study designs for their required sample size to detect relevant differences in polyp detection rates., Patients and Methods: Three commonly reported study designs were compared: design 1, the parallel randomized design; design 2, the randomized cross-over design with direct removal of polyps; and design 3, the randomized cross-over design without direct removal of polyps. A total of five different scenarios were analyzed per study design, representing a variety of clinical settings. Each scenario was repeated 1000 times for each study design and the sample size that produced a significant result per study design in each scenario was recorded., Results: In many scenarios, study design 1 required 10-15 times more patients to reach the same statistical power of 80% compared with study design 2. Further reductions in sample size could be achieved when study design 3 was used, although this design is limited by its impracticality., Conclusions: The randomized parallel design requires a larger sample size to achieve equivalent power to the cross-over design. Researchers should carefully consider whether the latter design could be used instead, as it requires a lower number of subjects, although it may be more cumbersome for patients, endoscopists, and researchers., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background and Study Aims: Radiofrequency ablation (RFA) is safe and effective for the eradication of neoplastic Barrett's esophagus; however, occasionally there is minimal regression after initial circumferential balloon-based RFA (c-RFA). This study aimed to identify predictive factors for a poor response 3 months after c-RFA, and to relate the percentage regression at 3 months to the final treatment outcome., Methods: We included consecutive patients from 14 centers who underwent c-RFA for high grade dysplasia at worst. Patient and treatment characteristics were registered prospectively. "Poor initial response" was defined as < 50 % regression of the Barrett's esophagus 3 months after c-RFA, graded by two expert endoscopists using endoscopic images. Predictors of initial response were identified through logistic regression analysis., Results: There were 278 patients included (median Barrett's segment C4M6). In poor initial responders (n = 36; 13 %), complete response for neoplasia (CR-neoplasia) was ultimately achieved in 86 % (vs. 98 % in good responders; P < 0.01) and complete response for intestinal metaplasia (CR-IM) in 66 % (vs. 95 %; P < 0.01). Poor responders required 13 months treatment (vs. 7 months; P < 0.01) for a median of four RFA sessions (vs. three; P < 0.01). We identified four independent baseline predictors of poor response: active reflux esophagitis (odds ratio [OR] 37.4; 95 % confidence interval [CI] 3.2 - 433.2); endoscopic resection scar regeneration with Barrett's epithelium (OR 4.7; 95 %CI 1.1 - 20.0); esophageal narrowing pre-RFA (OR 3.9; 95 %CI 1.0 - 15.1); and years of neoplasia pre-RFA (OR 1.2; 95 %CI 1.0 - 1.4)., Conclusions: Patients with a poor initial response to c-RFA have a lower ultimate success rate for CR-neoplasia/CR-IM, require more treatment sessions, and a longer treatment period. A poor initial response to c-RFA occurs more frequently in patients who regenerate their endoscopic resection scar with Barrett's epithelium, and those with ongoing reflux esophagitis, neoplasia in Barrett's esophagus for a longer time, or a narrow esophagus., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background and Study Aims: We previously developed a prognostic model for primary sclerosing cholangitis (PSC), which was primarily based on a cholangiographic classification of the intra- and extrahepatic biliary tree lesions. The aim of the present study was to validate the performance of this model in an external cohort., Patients and Methods: The validation dataset consisted of patients with PSC from a single referral center in Oslo, Norway. The patients' cholangiograms were scored according to the Amsterdam classification. We then examined whether adjusting the value of the original coefficients of the predictors or adding new predictors would improve the fit of the original model in the validation cohort. In addition, we evaluated calibration (closeness between observed and expected survival) and discrimination using the concordance index., Results: A total of 111 patients (mean age 35 +/- 13 years; 76 % male) were included in the validation study. Baseline clinical characteristics were comparable between the two cohorts. None of the coefficients that were re-estimated in the validation cohort differed significantly from the values of the original model. Observed and expected survival curves were in close agreement across different risk groups. Discrimination of the original model was preserved in the validation cohort: the concordance index was the same in both cohorts., Conclusions: The prognostic model showed adequate performance in an independent series of patients. Therefore, we updated the model using the data from both cohorts to provide more robust estimates of transplant-free survival for individual patients. A nomogram was constructed, which can be used to predict medium- and long-term prognosis in individual patients with PSC., (Copyright Georg Thieme Verlag KG Stuttgart . New York.)

Background and Study Aim: Patients with longstanding ulcerative colitis are at increased risk of developing colorectal cancer. Colonoscopic surveillance is advised, but the detection of neoplasia by conventional colonoscopy is difficult. The aim of this study was to compare the accuracy of narrow-band imaging (NBI), a new imaging technique, with standard colonoscopy for the detection of neoplasia in patients with longstanding ulcerative colitis., Patients and Methods: This was a prospective, randomized, crossover study of 42 patients with longstanding ulcerative colitis. All participants underwent NBI and conventional colonoscopy with at least 3 weeks between the procedures. Randomization determined the order of the examinations. Targeted biopsies were taken during both procedures; additional random biopsies were taken at conventional colonoscopy only. The number of patients with neoplasia detected by targeted biopsies was used to assess the sensitivity for each technique., Results: With NBI, 52 suspicious lesions were detected in 17 patients, compared with 28 suspicious lesions in 13 patients detected during conventional colonoscopy. Histopathological evaluation of targeted biopsies revealed 11 patients with neoplasia: in four patients the neoplasia was detected by both techniques, in four patients neoplasia was detected only by NBI, and in three patients neoplasia was detected only by conventional colonoscopy ( P = 0.705). Aside from targeted biopsies, 1522 random biopsies were taken. These revealed one additional patient with dysplasia that was not detected by either technique., Conclusions: The sensitivity of the studied first-generation NBI system for the detection of patients with neoplasia seems to be comparable to conventional colonoscopy, although more suspicious lesions were found during NBI. We believe that it is still too early to stop taking additional random biopsies at surveillance colonoscopy in patients with ulcerative colitis.