Analysis Of Relative Risk Factors Influencing Missing Of Colorectal Adenomas During Colonoscopy

Background and Aims： Colonoscopy is currently considered to be the goldstandard for detecting adenomatous polyps. However, colonoscopy is not perfectbecause a considerable number of adenomas can be missed during routine colonoscopy.Several foreign studies have reported that adenomas are missed during colonoscopicexamination at a rate that varies from6%to27%because of study heterogeneity. Thereasons why adenomas are missed may be various, and the adenoma miss rate affectscolonoscopic surveillance intervals and procedural quality. The aim of the current studywas to analyze the miss rates for colorectal adenomas during colonoscopy as well asrelative factors influencing the adenoma miss rate of per-patient and instruct theendoscopists to reduce the missing of colorectal adenomas during routine colonoscopy.Patients and Methods：This prospective study was performed at a single institution,which was strictly in accordance with the patient inclusion criteria and exclusion criteriato randomized investigate patients who underwent index and follow-up colonoscopy indigestive endoscopy center of General Hospital of Beijing Military Region during June2012and December2013. Detailed information of patients such as sex, age, date ofexamination, surveillance interval, bowel preparation and features of adenomas such assize, number, shape, location and pathology as well as colonoscopists, colonoscopicinsertion and withdrawal time was noted. In order to facilitate sorting and statistics weestablished the electronic files.432patients were enrolled as research object to analyze, compared the results of two colonoscopies and the missed adenomas was defined as theadenomas detected only during the second colonoscopy. In order to provide appropriatesurveillance interval of patients, this study calculated miss rates according topatient-based methods. The per-patient miss rate was calculated as the number ofpatients with adenomas missed during the first colonoscopy divided by the total numberof patients. Factors associated with the miss rates in these patients were analyzed.Chi-square test was used to analyze the relative factors influencing the adenoma missrate of per-patient. Then choose the meaningful factors into the logistic regressionmodel for multiple factors analysis.Results：The average surveillance interval of two colonoscopies is (10.70±5.34)months. Of a total of432patients with two colonoscopies,116had missed adenomas onfirst colonoscopy. Per-patient miss rate for adenomas was26.9%. Among them,per-patient miss rate for low-risk adenomas was higher than per-patient miss rate forhigh-risk one (21.1%vs5.8%,P<0.05). Of the colorectal carcinoma, none was missed.Per-patient miss rate for adenomas smaller than5mm was62.1%. Per-patient miss ratefor adenomas6-9mm and more than10mm were21.6%and16.3%, respectively（P<0.05）. Per-patient miss rate were significantly higher for flat type adenomas ascompared with protruded type adenomas(73.3%vs26.7%,P<0.05). Per-patient miss ratefor multiple parts of bowel, left colon and right colon were52.6%,26.7%and20.7%,respectively（P<0.05）. There is no statistical significance in patient`s gender(X2=3.380,P>0.05) and age (X2=4.562,P>0.05). Per-patient miss rate according to thenumber of adenomas detected during the initial examination was as follows:19.1%forpatients with one adenoma on the first examination,25.0%for two adenomas,33.3%for three and more than three adenomas, respectively (p<0.05). The per-patient miss rateaccording to the histology type of adenomas detected during the initial examination wasas follows:22.8%for patients with hyperplastic or inflammatory adenomas on the firstexamination,21.4%for low-risk adenomas,37.6%for high-risk adenomas, respectively(p<0.05). A higher miss rate of per-patient often occurred in primary colonoscopists, ascompared with experience colonoscopists (49.6%vs16.6%,P<0.05). Per-patient miss rate were significantly higher for poor and/or inadequate bowel preparation as comparedwith excellent and/or adequate bowel preparation (41.8%vs14.7%,P<0.05). Per-patientmiss rate according to the insertion time during the initial examination was as follows:36.2%for less than5minutes on the first examination,25.8%for5-10minutes, and19.1%for more than10minutes, respectively (p<0.05). There is no significantlydifference in per-patient miss rate of adenomas was found in the current study whencomparing procedures with a withdrawal time longer or shorter than6minutes (27.0%vs27.4%,p>0.05). Logistic regression analysis showed that the bigger the adenomasize,the lower likely there are to be missed adenomas (OR:0.341;95%CI:0.173-0.671).Also, The longer insertion time took, the lower the adenoma miss rate (OR:0.987;95%CI:0.981-0.994). Per-patient miss rate were lower for high-risk adenomas ascompared with low-risk adenomas (OR:0.324;95%CI:0.154-0.680). Adenomas happensin multiple parts of bowel easily lead to missing (OR:3.791;95%CI:1.505-9.546).Conclusions：1. A significant miss rates for adenomas exists during routine colonoscopy. Themissed diagnosis of adenomas is not only significantly associated with features ofmissed adenomas such as the size, shape, number, location et al, but also relativefactors with skills of colonoscopists, insertion time, withdrawal time and bowelpreparation influencing the per-patient miss rate of adenomas.2. The key is based on a high-quality index colonoscopy to avoid adenomas missingand improve adenomas detection rate during colonoscopy. Improving diagnosis andtreatment skills of colonoscopists and giving enough insertion and withdrawal time aswell as ensure good bowel preparation.3. Per-patient miss rate for high-risk adenomas is low. Selecting appropriatecolonoscopy surveillance interval may refer to colonoscopy follow-up guidelines andcombining with the characteristics of patients.