Burden and outcomes for complex perianal fistulas in Crohn's disease:Systematic review

AIM To systematically review the literature on epidemiology,disease burden, and treatment outcomes for Crohn's disease(CD) patients with complex perianal fistulas.METHODS PubMed, Embase, and Cochrane were searched for relevant articles(published 2000-November 2016) and congress abstracts(published 2011-November 2016).RESULTS Of 535 records reviewed, 62 relevant sources were identified(mostly small observational studies). The cumulative incidence of complex perianal fistulas in CD from two referral-centre studies was 12%-14%(follow-up time, 12 years in one study; not reported in the second study). Complex perianal fistulas result in greatly diminished quality of life; up to 59% of patients are at risk of faecal incontinence. Treatments include combinations of medical and surgical interventions and expanded allogeneic adipose-derived stem cells. High proportions of patients experience lack of or inadequate response to treatment(failure and relapse rates,respectively: medical, 12%-73% and 0%-41%; surgical:0%-100% and 11%.20%; combined medical/surgical:0%-80% and 0%-50%; stem cells: 29%-47% and not reported). Few studies(1 of infliximab; 3 of surgical interventions)have been conducted in treatment-refractory patients, a population with high unmet needs. Limited data exist on the clinical value of anti-tumour necrosis factor-α dose escalation in patients with complex perianal fistulas in CD.CONCLUSION Complex perianal fistulas in CD pose substantial clinical and humanistic burden. There is a need for effective treatments, especially for patients refractory to antitumour necrosis factor-α agents, as evidenced by high failure and relapse rates.

Mechanism of diarrhea in microscopic colitis

AIM： To search the pathophysiological mechanism of diarrhea based on daily stool weights, fecal electrolytes, osmotic gap and pH. METHODS： Seventy-six patients were included： 51 with microscopic colitis （MC） [40 with lymphocytic colitis （LC）; 11 with collagenous colitis （CC）], 7 with MC without diarrhea and 18 as a control group （CG）. They collected stool for 3 d. Sodium and potassium concentration were determined by flame photometry and chloride concentration by titration method of Schales. Fecal osmotic gap was calculated from the difference of osmolarity of fecal fluid and double sum of sodium and potassium concentration. RESULTS： Fecal fluid sodium concentration was significantly increased in LC 58.11±5.38 mmol/L （P〈0.01） and CC 54.14±8.42 mmol/L （P〈0.05） than in CG 34.28±2.98 mmol/L. Potassium concentration in LC 74.65±5.29 mmol/L （P〈0.01） and CC 75.53±8.78 mmol/L （P〈0.05） was significantly less compared to CG 92.67±2.99 mmol/L. Chloride concentration in CC 36.07±7.29 mmol/L was significantly higher than in CG 24.11±2.05 mmol/L（P〈0.05）. Forty-four （86.7%） patients had a secretory diarrhea compared to fecal osmotic gap. Seven （13.3%） patients had osmotic diarrhea. CONCLUSION： Diarrhea in MC mostly belongs to thesecretory type. The major pathophysiological mechanism in LC could be explained by a decrease of active sodium absorption. In CC, decreased CI/HCO3 exchange rate and increased chloride secretion are coexistent pathways.