Patrick Colquhoun

Interobserver and Intraobserver Bias Exists in the Interpretation of Anal Dysplasia

AbstractINTRODUCTION: Natural history of progression from anal intraepithelial neoplasia to invasive carcinoma remains unproven. The risk of progression may be linked to the severity of dysplasia. Important therapeutic decisions are thus based on the severity of anal intraepithelial neoplasia. Consistency and reliability in the interpretation of anal intraepithelial neoplasia are unproven. METHODS: One hundred ninety anal biopsy specimens were identified for review of dysplasia with a six-point grade system from normal to invasive cancer, evidence of human papillomavirus infection, and quality of histology by three pathologists. RESULTS: Results revealed poor to moderate agreement on grading of quality of histology (weighted kappa score, 0.07–0.22), human papillomavirus status (weighted kappa score, 0.24–0.53), and dysplasia (weighted kappa score, 0.38–0.7). Complete agreement between the original pathology and the three pathologists was observed in only 32 percent of cases. Analysis of 86 slides previously read by one of the pathologists revealed only moderate agreement, with a weighted kappa score of 0.64. CONCLUSION: Significant interobserver and intraobserver bias exists in the interpretation of anal intraepithelial neoplasia. These inconsistencies may explain the uncertainty about the natural progression of anal intraepithelial neoplasia and the varied results of surgery reported for anal intraepithelial neoplasia in the literature.

High compliance rates observed for follow up colonoscopy post polypectomy are achievable outside of clinical trials: efficacy of polypectomy is not reduced by low compliance for follow up

Introduction  The National Polyp Study demonstrated that removal of adenomas with at least a three‐year follow up reduced the incidence of colorectal cancer. However, compliance with follow up colonoscopy may affect the estimates of reduction in colorectal cancer incidence demonstrated by the National Polyp Study. While an 80% compliance rate for follow up colonoscopy was achieved during the National Polyp Study, the compliance rate for follow up colonoscopy is unknown in the general population. The aim of this study was to determine the compliance rate for follow up colonoscopy and factors which affect follow up.

Horseshoe Abscesses and Fistulas: How Are We Doing?

Background:Various surgical treatments exist for horseshoe abscesses and fistulae, including posterior midline sphincterotomy, catheter drainage, cutting and draining setons, and advancement flaps. The aim of this study was to evaluate the long-term results of patients treated for these complex anorectal problems. Methods: A retrospective review was undertaken of patients with a diagnosis of horseshoe abscess, horseshoe fistula, postanal space abscess, or postanal space fistula from 1990 to 2001. Long-term follow-up was accomplished by telephone questionnaire. Results: Thirty-one patients were identified, of whom 17 (54.8%) had a diagnosis of Crohn disease. The diagnosis at presentation included unilateral (ischiorectal) abscess (32.3%), bilateral horseshoe abscess (51.6%), bilateral horseshoe fistula (9.7%), and postanal space abscess (6.4%). Endoanal ultrasonography was used during the preoperative evaluation in 11 patients (35.5%). After referral to our institution, patients underwent a median of four operations (range, 1 to 9). At a mean follow-up of 49.3 months, 60.7% of patients had either healed perineal disease or were asymptomatic with controlled disease. Patients who had a posterior midline sphincterotomy were more likely to be asymptomatic (P = .047). Patients who had a diagnosis of Crohn disease required more operations than those without Crohn disease (3 vs 1.86, P= .02). Only patients who had a diagnosis of Crohn disease had a stoma at their last follow-up (4 of 17, 23.5% vs 0 of 11, 0%; P=.05). Conclusions: Patients with horseshoe abscess or fistulae often require multiple operations for treatment but can expect reasonable rates of long-term success in controlling or curing their disease. Those who undergo posterior midline sphincterotomy seem to benefit with higher rates of improved symptoms. Patients with a diagnosis of Crohn disease may fare less well. The role of endoanal ultrasonography in directing therapy remains to be defined.

Can the procedure for prolapsing hemorrhoids (PPH) be done twice? Results of a porcine model

AbstractBackground: The procedure for prolapsing hemorrhoids (PPH) is a new surgical method for the treatment of symptomatic hemorrhoids. In cases of recurrent prolapse, the performance of a second PPH may result in a ring of mucosa and submucosa between the two circular staple lines. In this study, we used a porcine model to assess whether PPH can be safely performed twice. Methods: Five adult pigs underwent two PPH procedures in one session, leaving a ring of ~1 cm of mucosa between the two staple lines. One month later, the pigs were examined under anesthesia. The anal canal was assessed using the following four methods: (a) clinical examination, (b) evaluation of mucosal blood perfusion at different levels of the anal canal via a laser Doppler flow detector, (c) measurement of concentrations of hydroxyproline and collagen to check for fibrosis, and (d) histopathological examination. Results: At the completion of the study period, all five pigs showed no clinical evidence of anorectal dysfunction. On examination under anesthesia 1 month after surgery, there was no evidence of anal stenosis in any of the pigs. The mean mucosal blood flow between the two staple lines did not differ significantly from the flow measured proximally and distally (394 vs 363 and 339 flow units, respectively; p = NS). The collagen levels, based on hydroxyproline concentration, were 81 mcg/mg between the staple lines, compared to 82 and 79 proximally and distally, respectively (p = NS). There was no significant difference in degree of fibrosis, as assessed histopathologically, between specimens taken from the ring between the staple lines and specimens taken from the area external to the staple lines. Conclusions: The results of this porcine model suggest that a second synchronous PPH is feasible. A controlled experience involving human subjects is required to determine the safety and usefulness of this technique in cases of metachronous application for recurrent or residual hemorrhoids.

The use of "spin" in laparoscopic lower GI surgical trials with nonsignificant results: an assessment of reporting and interpretation of the primary outcomes.

BACKGROUND: Spin has been defined as “specific reporting that could distort the interpretation of results and mislead readers.” OBJECTIVE: The purpose of this study was to identify how frequently, and to what extent, “spin” occurs in laparoscopic lower GI surgical trials with nonsignificant results. DATA SOURCES: Publications were referenced in MEDLINE and EMBASE (1992–2012). STUDY SELECTION: Randomized controlled trials comparing laparoscopic with open surgical technique in lower GI surgery were sought. Trials were included if a nonsignificant (p > 0.05) result of the primary outcome(s) occurred. INTERVENTION: The laparoscopic versus open technique in lower GI surgery was studied. MAIN OUTCOME MEASURES: Trials were assessed for frequency, strategy, and extent of “spin,” as previously defined. RESULTS: Fifty-eight trials met the inclusion criteria. Sixty-six percent of these trials had evidence of “spin.” In general, authors used significant results only (one of multiple primary outcomes, secondary outcomes, or subgroup analyses) (43%) or interpreted nonsignificance as equivalence (43%). Trials with spin were more likely to recommend the laparoscopic approach over the open technique (p < 0.001), were less likely to call for further trials (p = 0.003), and were less likely to acknowledge the nonsignificant differences (p < 0.001). Inadequate randomization was associated with decreased odds of spin (p = 0.03), as was an intent-to-treat analysis (p < 0.0001), whereas inadequate allocation concealment (p = 0.06) was weakly associated with a decrease in spin. No other a priori candidate risk factors were associated with the presence of spin. LIMITATIONS: Funding source was rarely described, so the association between industry funding and spin could not be assessed. CONCLUSION: The distortion of nonsignificant results in laparoscopic trials was highly prevalent in this review. Readers of trials with nonsignificant results should be cautious of the authors’ interpretations. Editors, reviewers, and publishers should ensure that author’s conclusions correspond to the study’s results and design.

Small bowel transit does not correlate with outcome of surgery in patients with colonic inertia.

Colonic inertia is a motility disorder that may involve dysfunction of the entire intestinal tract. The aim of this study was to assess whether small bowel transit time is associated with the outcome of total abdominal colectomy in patients with colonic inertia. A retrospective review of the medical records of patients who underwent total abdominal colectomy for colonic inertia was performed to identify those individuals who had a preoperative small bowel transit study. The outcome of surgery was correlated with the results of the small bowel transit study. Fifty-two female patients underwent total abdominal colectomy for colonic inertia between 1988 and 2000, of whom 17 (33%) had a preoperative small bowel transit study. The small bowel transit time was normal in 11 patients (65%), and the time was abnormally prolonged in 6 (35%). At a mean follow-up of 37 months, there was no significant difference in the outcome of surgery between the two groups. A good result was achieved in 36% of the normal small bowel transit time group compared with 33% in the abnormal group; the result was fair in 63% and 33%, and poor in 0% and 33%, respectively (P= NS). The small bowel transit study does not reliably predict the outcome of total abdominal colectomy in patients with colonic inertia.

Colorectal cancer screening: do we practice what we preach?

Objective: Compliance rates for colorectal cancer screening have been reported as low, and ignorance is the most common factor sighted to explain this. The aim of this study was to determine screening compliance among colorectal surgeons assumed to be educated of the risks of colorectal cancer. Methods: A postal survey was distributed to the members of the American Society of Colon and Rectal Surgeons. Results: A total of 1195 members were surveyed. All respondents indicated that they advocate screening. Colonoscopy every 10 years and annual fecal occult blood testing were the most common strategies advocated to individuals with baseline risk. Colonoscopy every 5 years and annual fecal occult blood testing were the most common strategies advocated to patients with a first-degree relative with polyps or cancer. Most of these colorectal surgeons initiated their screening before 50 years of age. Conclusion: Colorectal cancer screening compliance is high among members of the American Society of Colon and Rectal Surgeons. These rates may be the result of awareness of the risks of colorectal cancer.

Colorectal cancer screening: do they practice what they preach?

Introduction:  Compliance for voluntary colorectal cancer (CRC) screening reported by the American Society of Colon and Rectal Surgeons (ASCRS) is>85%. This high rate is assumed to be the result of heightened awareness of CRC. The purpose of the present paper was to determine if observed participation rates in the USA are the result of increased awareness of CRC alone.