Chronic methadone use,poor bowel visualization and failed colonoscopy:A preliminary study

AIM:To examine effects of chronic methadone usage on bowel visualization,preparation,and repeat colonoscopy.METHODS:In-patient colonoscopy reports from October,2004 to May,2009 for methadone dependent(MD) patients were retrospectively evaluated and compared to matched opioid naive controls(C).Strict criteria were applied to exclude patients with risk factors known to cause constipation or gastric dysmotility.Colonoscopy reports of all eligible patients were analyzed for degree of bowel visualization,assessment of bowel preparation(good,fair,or poor),and whether a repeat colonoscopy was required.Bowel visualization was scored on a 4 point scale based on multiple prior studies:excellent = 1,good = 2,fair = 3,or poor = 4.Analysis of variance(ANOVA) and Pearson χ 2 test were used for data analyses.Subgroup analysis included correlation between methadone dose and colonoscopy outcomes.All variables significantly differing between MD and C groups were included in both univariate and multivariate logistic regression analyses.P values were two sided,and < 0.05 were considered statistically significant.RESULTS:After applying exclusionary criteria,a total of 178 MD patients and 115 C patients underwent a colonoscopy during the designated study period.A total of 67 colonoscopy reports for MD patients and 72 for C were included for data analysis.Age and gender matched controls were randomly selected from this population to serve as controls in a numerically comparable group.The average age for MD patients was 52.2 ± 9.2 years(range:32-72 years) years compared to 54.6 ± 15.5 years(range:20-81 years) for C(P = 0.27).Sixty nine percent of patients in MD and 65% in C group were males(P = 0.67).When evaluating colonoscopy reports for bowel visualization,MD patients had significantly greater percentage of solid stool(i.e.,poor visualization) compared to C(40.3% vs 6.9%,P < 0.001).Poor bowel preparation(35.8% vs 9.7%,P < 0.001) and need for repeat colonoscopy(32.8% vs 12.5%,P = 0.004) were significantly higher in MD group compared to C,respectively.Under univariate analysis,factors significantly associated with MD group were presence of fecal particulate [odds ratio(OR),3.89,95% CI:1.33-11.36,P = 0.01] and solid stool(OR,13.5,95% CI:4.21-43.31,P < 0.001).Fair(OR,3.82,95% CI:1.63-8.96,P = 0.002) and poor(OR,8.10,95% CI:3.05-21.56,P < 0.001) assessment of bowel preparation were more likely to be associated with MD patients.Requirement for repeat colonoscopy was also significant higher in MD group(OR,3.42,95% CI:1.44-8.13,P = 0.01).In the multivariate analyses,the only variable independently associated with MD group was presence of solid stool(OR,7.77,95% CI:1.66-36.47,P = 0.01).Subgroup analysis demonstrated a general trend towards poorer bowel visualization with higher methadone dosage.ANOVA analysis demonstrated that mean methadone dose associated with presence of solid stool(poor visualization) was significantly higher compared to mean dosage for clean colon(excellent visualization,P = 0.02) or for those with liquid stool only(good visualization,P = 0.01).CONCLUSION:Methadone dependence is a risk factor for poor bowel visualization and leads to more repeat colonoscopies.More aggressive bowel preparation may be needed in MD patients.

Colometer:A real-time quality feedback system for screening colonoscopy

AIM:To investigate the performance of a new software-based colonoscopy quality assessment system.METHODS:The software-based system employs a novel image processing algorithm which detects the levels of image clarity,withdrawal velocity,and level of the bowel preparation in a real-time fashion from live video signal.Threshold levels of image blurriness and the withdrawal velocity below which the visualization could be considered adequate have initially been determined arbitrarily by review of sample colonoscopy videos by two experienced endoscopists.Subsequently,an overall colonoscopy quality rating was computed based on the percentage of the withdrawal time with adequate visualization(scored 1-5;1,when the percentage was 1%-20%;2,when the percentage was 21%-40%,etc.).In order to test the proposed velocity and blurriness thresholds,screening colonoscopy withdrawal videos from a specialized ambulatory colon cancer screening center were collected,automatically processed and rated.Quality ratings on the withdrawal were compared to the insertion in the same patients.Then,3 experienced endoscopists reviewed the collected videos in a blinded fashion and rated the overall quality of each withdrawal(scored 1-5;1,poor;3,average;5,excellent) based on 3 major aspects:image quality,colon preparation,and withdrawal velocity.The automated quality ratings were compared to the averaged endoscopist quality ratings using Spearman correlation coefficient.RESULTS:Fourteen screening colonoscopies were assessed.Adenomatous polyps were detected in 4/14(29%) of the collected colonoscopy video samples.As a proof of concept,the Colometer software rated colonoscope withdrawal as having better visualization than the insertion in the 10 videos which did not have any polyps(average percent time with adequate visualization:79% ± 5% for withdrawal and 50% ± 14% for insertion,P < 0.01).Withdrawal times during which no polyps were removed ranged from 4-12 min.The median quality rating from the automated system and the reviewers was 3.45 [interquartile range(IQR),3.1-3.68] and 3.00(IQR,2.33-3.67) respectively for all colonoscopy video samples.The automated rating revealed a strong correlation with the reviewer's rating(ρ coefficient= 0.65,P = 0.01).There was good correlation of the automated overall quality rating and the mean endoscopist withdrawal speed rating(Spearman r coefficient= 0.59,P = 0.03).There was no correlation of automated overall quality rating with mean endoscopists image quality rating(Spearman r coefficient= 0.41,P = 0.15).CONCLUSION:The results from a novel automated real-time colonoscopy quality feedback system strongly agreed with the endoscopists' quality assessments.Further study is required to validate this approach.

Lower body weight and female gender:Hyperphosphatemia risk factors after sodium phosphate preparations

Casals et al have reported an inverse correlation between serum phosphate and body weight after administration of sodium phosphate at a dose of 60 g. Our group has already described the relationship between body weight and hyperphosphatemia with these preparations, although our study was not quoted by Casals. We performed a pharmacokinetic study involving 13 volunteers who were divided into two groups on the basis of body weight： group I consisting of seven women with a median weight of 60 kg and group Ⅱ consisting of five men and one woman with a median weight of 119.2 kg. Group Ⅰdeveloped higher peak phosphate levels and maintained these levels above the subjects in Group Ⅱ for a prolonged time period despite adequate hydration being ensured with frequent monitoring of weight, fluid intake and total body weight. Our studydemonstrated that adequate hydration does not protect against the secondary effects of hyperphosphatemia. In the study by Casais et al, 66% of the study subjects were women, the correlation between serum phosphate and gender in their data also appears to be important. Women are at higher risk of acute phosphate nephropathy due to a diminished volume of distribution of the high dose of ingested phosphate. Decreased volume of distribution in women is due to diminished body weight. This is further compounded by decreased creatinine clearance in females.