Alexander C. von Roon
St Mary's Hospital
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Featured researches published by Alexander C. von Roon.
The American Journal of Gastroenterology | 2007
Alexander C. von Roon; Leonidas Karamountzos; Sanjay Purkayastha; George E. Reese; Ara Darzi; Julian Teare; Paraskevas Paraskeva; Paris P. Tekkis
OBJECTIVES:Fecal calprotectin (FC) is a relatively new marker of intraluminal intestinal inflammation. Using meta-analytical techniques, the study aimed to evaluate the diagnostic precision of FC for inflammatory bowel disease (IBD) and colorectal cancer (CRC) in adults and children.METHODS:Quantitative meta-analysis was performed on prospective studies, comparing FC levels against the histological diagnosis. Sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated for each study. Summary receiver-operating characteristic (sROC) curves and subgroup analysis were undertaken. Study quality and heterogeneity were evaluated.RESULTS:Thirty studies of 5,983 patients were included. FC levels in patients with IBD were higher by 219.2 micrograms per gram (μg/g) compared with normal patients (P < 0.001). sROC curve analysis showed a sensitivity of 0.95 (95% CI 0.93–0.97), specificity of 0.91 (95% CI 0.86–0.91), and an area under the curve (AUC) of 0.95 for the diagnosis of IBD. Patients with colorectal neoplasia had nonsignificantly higher FC levels by 132.2 μg/g compared with noncancer controls (P = 0.18). Sensitivity and specificity of FC for the diagnosis of CRC were 0.36 and 0.71, respectively, with an AUC of 0.66. The diagnostic precision of FC for IBD was higher in children than adults with better accuracy at a cutoff level of 100 μg/g versus 50 μg/g. Sensitivity analysis and metaregression analysis did not significantly alter the results.CONCLUSIONS:FC cannot be recommended as a screening test for CRC in the general population. FC appeared to offer a good diagnostic precision in distinguishing IBD from non-IBD diagnoses, with higher precision at a cutoff of 100 μg/g.
Diseases of The Colon & Rectum | 2007
Alexander C. von Roon; George E. Reese; Julian Teare; Vasilis A. Constantinides; Ara Darzi; Paris P. Tekkis
PurposeThe risk of cancer in patients with Crohn’s disease is not well defined. Using meta-analytical techniques, the present study was designed to quantify the risk of intestinal, extraintestinal, and hemopoietic malignancies in such patients.MethodsA literature search identified 34 studies of 60,122 patients with Crohn’s disease. The incidence and relative risk of cancer were calculated for patients with Crohn’s disease and compared with the baseline population of patients without Crohn’s disease. Overall pooled estimates, with 95 percent confidence intervals, were obtained, using a random-effects model.ResultsThe relative risk of small bowel, colorectal, extraintestinal cancer, and lymphoma compared with the baseline population was 28.4 (95 percent confidence interval, 14.46–55.66), 2.4 (95 percent confidence interval, 1.56–4.36), 1.27 (95 percent confidence interval, 1.1–1.47), and 1.42 (95 percent confidence interval, 1.16–1.73), respectively. On subgroup analysis, patients with Crohn’s disease had an increased risk of colon cancer (relative risk, 2.59; 95 percent confidence interval, 1.54–4.36) but not of rectal cancer (relative risk, 1.46; 95 percent confidence interval, 0.8–2.55). There was significant association between the anatomic location of the diseased bowel and the risk of cancer in that segment. The risk of small bowel cancer and colorectal cancer was found to be higher in North America and the United Kingdom than in Scandinavian countries with no evidence of temporal changes in the cancer incidence.ConclusionsThe present meta-analysis demonstrated an increased risk of small bowel, colon, extraintestinal cancers, and lymphoma in patients with Crohn’s disease. Patients with extensive colonic disease that has been present from a young age should be candidates for endoscopic surveillance; however, further data are required to evaluate the risk of neoplasia over time.
Diseases of The Colon & Rectum | 2006
Richard E. Lovegrove; Henry S. Tilney; Alexander G. Heriot; Alexander C. von Roon; Thanos Athanasiou; James M. Church; Victor W. Fazio; Paris P. Tekkis
PurposeRestorative proctocolectomy is the procedure of choice for patients undergoing proctocolectomy for familial adenomatous polyposis or ulcerative colitis. This meta-analysis was designed to identify differences in adverse events and functional outcomes between these two groups.MethodsStudies published between 1986 and 2003 that compared outcomes between patients with familial adenomatous polyposis and ulcerative colitis were included. Meta-analytical techniques using random effect models were used to compare short-term and long-term adverse events as well as functional outcomes between the groups.ResultsNineteen studies comprising 5,199 patients (familial adenomatous polyposis, 782; ulcerative colitis, 4,417) were analyzed. There were no significant differences in immediate postoperative adverse events between the two groups. Pouch-related fistulation was significantly increased in the ulcerative colitis group (10.5 percent vs. familial adenomatous polyposis 4.8 percent; odds ratio 2.31; P < 0.001). There was no significant difference in pouch failure between the two groups (ulcerative colitis 5.8 percent vs. familial adenomatous polyposis 4.5 percent; odds ratio 1.22; P = 0.43). The incidence of pouchitis was significantly greater in the ulcerative colitis group (30.1 vs. 5.5 percent; odds ratio 6.44; P < 0.001). Patients with familial adenomatous polyposis had a significant advantage in stool frequency with one less motion per 24 hours (95 percent confidence interval, 0.21–1.76; P = 0.01).ConclusionsIn contrast to studies reporting similar outcomes for patients undergoing restorative proctocolectomy for familial adenomatous polyposis or ulcerative colitis, the present meta-analysis suggested that patients with ulcerative colitis are at greater risk of pouch-related fistulation and pouchitis. Although there was an increase in the 24-hour stool frequency in the ulcerative colitis group, this may be accounted for by the younger age at surgery in the familial adenomatous polyposis group.
Annals of Surgery | 2011
Alexander C. von Roon; Olivia C. C. Will; R. Man; Kay Neale; Robin K. S. Phillips; R. John Nicholls; Susan K. Clark; Paris P. Tekkis
OBJECTIVE The study compared the risk of adenoma or carcinoma formation in the anorectal segment after either mucosectomy with manual anastomosis or stapled ileoanal anastomosis (IAA) following restorative proctocolectomy (RPC) for familial adenomatous polyposis (FAP). BACKGROUND Few data exist on the risk of adenoma formation after either technique in FAP. METHODS All endoscopy and histology reports for patients having RPC for FAP attending for annual pouchoscopy from 1978 to 2007 were reviewed. The incidence, timing, and histological characteristics of adenoma or carcinoma formation were recorded. RESULTS Of the 206 patients, 140 attended for endoscopic follow-up for a median of 10.3 years after RPC. Fifty-two patients developed neoplastic transformation in the anorectal segment, with a cumulative risk at 10 years of 22.6% after mucosectomy with manual anastomosis and 51.1% after stapled IAA (P < 0.001). The median time to first adenoma was longer after mucosectomy with handsewn anastomosis than after stapled IAA (10.1 vs 6.5 years, P < 0.001). On multivariate analysis, stapled IAA (hazard ratio= 3.45, 95% confidence interval = 1.01–4.98) and age at RPC older than 40 years (hazard ratio = 2.20, 95% confidence interval = 1.01–4.89) were significantly associated with increased risk of adenoma formation. Nine patients developed a large (>10 mm) adenoma. One patient (handsewn ileoanal anastomosis) developed adenocarcinoma in the anorectal mucosa at 13 years and required pouch excision. CONCLUSIONS Adenoma formation in the anorectal mucosa after RPC for FAP is common but carcinoma is rare. The risk is lower after mucosectomy with handsewn anastomosis than after stapled IAA. Regular endoscopic surveillance after either technique is mandatory.
Diseases of The Colon & Rectum | 2007
Alexander C. von Roon; Paris P. Tekkis; Susan K. Clark; Alexander G. Heriot; Richard E. Lovegrove; Simona Truvolo; R. John Nicholls; Robin K. S. Phillips
PurposeThis study was designed to assess the impact of technical factors on functional outcomes and complications in patients undergoing restorative proctocolectomy for familial adenomatous polyposis.MethodsThis was a descriptive study on 189 patients undergoing restorative proctocolectomy in a single tertiary referral center between 1977 and 2003. Primary outcomes were major complications, pouch function, and neoplastic transformation in the anal transitional zone.ResultsPouch construction was J-reservoir (60 percent), W-reservoir (34 percent), or S-reservoir (6 percent), with double-stapled (31 percent) or handsewn anastomosis with mucosectomy (69 percent). Overall pouch survival was 96 percent at five years and 89 percent at ten years, with no differences according to pouch design or anastomotic technique. The incidence of pelvic sepsis was unaffected by anastomotic technique (stapled vs. handsewn; 12 vs. 13 percent) or type of reservoir (J- vs. W- vs. S-pouch; 16 vs. 9 vs. 10 percent). Fistula formation was independent of anastomotic technique (stapled vs. handsewn; 8 vs. 8 percent) and type of reservoir (J- vs. W- vs. S-pouch; 9 vs. 7 vs. 0 percent). The night-time and 24-hour bowel frequencies were similar with the two anastomotic techniques and types of reservoirs. The incidence of polyps at the anal transitional zone was lower with handsewn than with stapled anastomosis (19 vs. 38 percent; P = 0.047).ConclusionsRestorative proctocolectomy in patients with familial adenomatous polyposis has good functional outcomes and an acceptable rate of complications, which are independent of choice of technique. Handsewn ileoanal anastomosis with mucosectomy seems to reduce the incidence of subsequent neoplasia in the anal transitional zone but does not eliminate the risk of cancer.
The American Journal of Gastroenterology | 2012
Brian H. Shirts; Alexander C. von Roon; Anne E. Tebo
The Entire Predictive Value of the Prometheus IBD sgi Diagnostic Product May be Due to the Three Least Expensive and Most Available Components
Cirugia Espanola | 2014
Antonio Navarro-Sánchez; Alexander C. von Roon; Rhys L. Thomas; Stephen Windsor Marchington; Alberto M. Isla
We used a defrosted porcine aorta segment as a simile of the human main biliary duct. After inserting several chick peas into the aortic lumen to represent gallstones, both ends were ligated and affixed to a cork sheet, which was then placed inside a standard laparoscopic training box. For the insertion of the choledochoscope, it was necessary to make a 15 mm longitudinal incision with the laparoscopic scissors to simulate a choledochotomy. This allowed for proximal and distal exploration, and the chick peas were able to be extracted with a dormia basket. Both the laparoscopic and endoscopic visions achieved were very similar to an authentic surgical setting (Figs. 1 and 2). The model was also used to practice laparoscopic placement of T-tube drains and for the suture of the ‘‘bile duct’’. The students worked in pairs: one handled the choledochoscope, and the other the laparoscope and the dormia basket.
Current Gastroenterology Reports | 2008
James Kinross; Alexander C. von Roon; Elaine Holmes; Ara Darzi; Jeremy K. Nicholson
Current Pharmaceutical Design | 2009
James Kinross; Alexander C. von Roon; Nicholas Penney; Elaine Holmes; David B. Silk; Jeremy K. Nicholson; Ara Darzi
Diseases of The Colon & Rectum | 2007
Alexander C. von Roon; George E. Reese; Julian Teare; Vasilis A. Constantinides; Ara Darzi; Paris P. Tekkis