Cap Assisted Colonoscopy for the Detection of Serrated Polyps
Cap Assisted Colonoscopy for the Detection of Serrated Polyps
We conducted a post hoc analysis of a previously conducted randomized controlled trial comparing standard (SC) and cap assisted colonoscopy (CAC) for adenoma detection. The original study was a prospective randomized controlled trial conducted at the Kansas City Veterans Affairs Medical Center and was approved by its Institutional Review Board (KCVA IRB) and was registered at http://clinicaltrial.gov (NCT 01211132). The primary results have been previously reported.
Subjects who were referred for screening or surveillance colonoscopy were prospectively enrolled between September 2009 and October 2010. Subjects were included in the study if they were referred for a screening or surveillance colonoscopy and agreed to provide a written informed consent. The procedure was considered a screening one if the patient never had a colonoscopy before or if no polyps were detected on previous colonoscopies. On the other hand, subjects with a history of adenoma on a prior colonoscopy and who were referred for follow-up were deemed to be undergoing surveillance colonoscopy.
The exclusion criteria of the study included previous surgical resection of any part of the colon, personal history of colon cancer, history of inflammatory bowel disease, use of antiplatelet agents or anti-coagulants that precluded removal of polyps, poor general condition or any other reason to avoid prolonged procedure time, history of polyposis syndrome or hereditary nonpolyposis colorectal cancer, or the inability to give an informed consent.
Following enrollment and randomization to one of the arms, those subjects who had inadequate colon preparation or in whom the cecum could not be reached were also excluded. Different patient parameters were recorded included demographics (age, gender and race), indication of colonoscopy, body mass index (BMI), family history of colorectal cancer (first-degree relative), history of smoking, and history of prior abdominal surgery.
Following enrollment, subjects were randomized to undergo either SC or CAC by opening an opaque sealed envelope containing the procedure allocation. The randomization sequence was stratified by the indication of colonoscopy (screening vs. surveillance) and was generated by the statistician with a computerized randomization scheme using block sizes of 10.
Moderate sedation was used in the study using intravenous midazolam in combination with either meperidine or fentanyl. The colonoscope was inserted and advanced to the cecum. Careful mucosal inspection and polypectomies were performed during the withdrawal phase. Procedural times were recorded using a stopwatch (the cecal intubation time as well as withdrawal time). The stopwatch was not paused during any maneuver intended to assist cecal intubation (like suctioning of fluid, cleaning of the mucosa, abdominal pressure, or changing of position). The cecum was identified using the landmarks including the appendiceal orifice (which was photo documented) and intubation of the terminal ileum was attempted in all cases and its successful intubation was recorded. The withdrawal time in the study was defined as the time spent on mucosal inspection while the colonoscope was being withdrawn. The stopwatch was paused whenever the colonic mucosa was not being examined (for example during suctioning of fluid or during biopsies and polypectomy). In the CAC procedures, the cap was used to flatten the mucosal folds in order to inspect their proximal aspect for polyps.
Bowel preparation was evaluated and was then classified into four categories as follows: excellent (>90% of mucosa seen, the colonic contents were mostly liquid with minimal suctioning needed for clearing the mucosa), good (same as excellent except that significant suctioning was needed for clearing the mucosa), fair same as excellent except that the colonic contents were a mixture of liquid and semisolid which could be suctioned and/or washed), and inadequate (<90% of mucosa seen, the colonic contents were a mixture of semisolid and solid colonic contents, which could not be suctioned or washed). All procedural complications were recorded (like bleeding or perforation). Endoscopists were asked to document any technical difficult encountered with the cap like cap dislodgement or any difficulty in suctioning fluid or cleaning the mucosa or during therapeutic interventions attributable to the cap.
All analyses were performed using Stata/IC V.10.1 (StataCorp). The original study was powered to the primary end point that was the proportion of subjects with at least one adenoma. Fisher's exact test, t test, and Wilcoxon rank sum test were used to compare the differences across the two study groups regarding the total number of subjects with significant serrated polyps as well as the total number of significant serrated polyps detected. Similar comparisons were made for the individual categories of serrated polyps. A p value <0.05 was considered statistically significant and the results were reported in accordance to the guidelines of CONSORT 2010 and Standards for Reporting of Diagnostic Accuracy.
Significant serrated polyps were defined in this study as sessile serrated adenoma/polyp, traditional serrated adenoma, proximal hyperplastic polyps and large (≥1 cm) hyperplastic polyp.
All specimens were reviewed by an expert GI-pathologist who is well-familiar with the recent WHO classification for serrated polyposis.
Methods
Study Design
We conducted a post hoc analysis of a previously conducted randomized controlled trial comparing standard (SC) and cap assisted colonoscopy (CAC) for adenoma detection. The original study was a prospective randomized controlled trial conducted at the Kansas City Veterans Affairs Medical Center and was approved by its Institutional Review Board (KCVA IRB) and was registered at http://clinicaltrial.gov (NCT 01211132). The primary results have been previously reported.
Study Subjects
Subjects who were referred for screening or surveillance colonoscopy were prospectively enrolled between September 2009 and October 2010. Subjects were included in the study if they were referred for a screening or surveillance colonoscopy and agreed to provide a written informed consent. The procedure was considered a screening one if the patient never had a colonoscopy before or if no polyps were detected on previous colonoscopies. On the other hand, subjects with a history of adenoma on a prior colonoscopy and who were referred for follow-up were deemed to be undergoing surveillance colonoscopy.
The exclusion criteria of the study included previous surgical resection of any part of the colon, personal history of colon cancer, history of inflammatory bowel disease, use of antiplatelet agents or anti-coagulants that precluded removal of polyps, poor general condition or any other reason to avoid prolonged procedure time, history of polyposis syndrome or hereditary nonpolyposis colorectal cancer, or the inability to give an informed consent.
Following enrollment and randomization to one of the arms, those subjects who had inadequate colon preparation or in whom the cecum could not be reached were also excluded. Different patient parameters were recorded included demographics (age, gender and race), indication of colonoscopy, body mass index (BMI), family history of colorectal cancer (first-degree relative), history of smoking, and history of prior abdominal surgery.
Randomization
Following enrollment, subjects were randomized to undergo either SC or CAC by opening an opaque sealed envelope containing the procedure allocation. The randomization sequence was stratified by the indication of colonoscopy (screening vs. surveillance) and was generated by the statistician with a computerized randomization scheme using block sizes of 10.
Colonoscopy Procedure
Moderate sedation was used in the study using intravenous midazolam in combination with either meperidine or fentanyl. The colonoscope was inserted and advanced to the cecum. Careful mucosal inspection and polypectomies were performed during the withdrawal phase. Procedural times were recorded using a stopwatch (the cecal intubation time as well as withdrawal time). The stopwatch was not paused during any maneuver intended to assist cecal intubation (like suctioning of fluid, cleaning of the mucosa, abdominal pressure, or changing of position). The cecum was identified using the landmarks including the appendiceal orifice (which was photo documented) and intubation of the terminal ileum was attempted in all cases and its successful intubation was recorded. The withdrawal time in the study was defined as the time spent on mucosal inspection while the colonoscope was being withdrawn. The stopwatch was paused whenever the colonic mucosa was not being examined (for example during suctioning of fluid or during biopsies and polypectomy). In the CAC procedures, the cap was used to flatten the mucosal folds in order to inspect their proximal aspect for polyps.
Bowel preparation was evaluated and was then classified into four categories as follows: excellent (>90% of mucosa seen, the colonic contents were mostly liquid with minimal suctioning needed for clearing the mucosa), good (same as excellent except that significant suctioning was needed for clearing the mucosa), fair same as excellent except that the colonic contents were a mixture of liquid and semisolid which could be suctioned and/or washed), and inadequate (<90% of mucosa seen, the colonic contents were a mixture of semisolid and solid colonic contents, which could not be suctioned or washed). All procedural complications were recorded (like bleeding or perforation). Endoscopists were asked to document any technical difficult encountered with the cap like cap dislodgement or any difficulty in suctioning fluid or cleaning the mucosa or during therapeutic interventions attributable to the cap.
Study Endpoints and Statistical Analysis
All analyses were performed using Stata/IC V.10.1 (StataCorp). The original study was powered to the primary end point that was the proportion of subjects with at least one adenoma. Fisher's exact test, t test, and Wilcoxon rank sum test were used to compare the differences across the two study groups regarding the total number of subjects with significant serrated polyps as well as the total number of significant serrated polyps detected. Similar comparisons were made for the individual categories of serrated polyps. A p value <0.05 was considered statistically significant and the results were reported in accordance to the guidelines of CONSORT 2010 and Standards for Reporting of Diagnostic Accuracy.
Definitions
Significant serrated polyps were defined in this study as sessile serrated adenoma/polyp, traditional serrated adenoma, proximal hyperplastic polyps and large (≥1 cm) hyperplastic polyp.
Pathology Review
All specimens were reviewed by an expert GI-pathologist who is well-familiar with the recent WHO classification for serrated polyposis.
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