5-aminosalicylate-intolerant patients are at increased risk of colectomy for ulcerative colitis

Background Although 5-aminosalicylate (5-ASA) is the therapy of first choice in ulcerative colitis (UC), some patients cannot tolerate it because of side effects. Previous reports have not investigated whether 5-ASA intolerance is associated with the risk of colectomy. Aim To investigate the associations between 5-ASA tolerance and colectomy among UC patients Methods The data of UC patients who visited any of three hospitals during 2014-2018 in and around Tokyo, Japan, were retrospectively obtained from the medical records. Patients were categorized as (a) tolerant to any 5-ASA compounds ("tolerant to 5-ASA") and (b) patients who were intolerant to one or more 5-ASA compounds leading to refrainment from their further use ("intolerant to 5-ASA"). The association between 5-ASA tolerance and colectomy was examined by Cox proportional hazards model adjusted for sex, age, smoking and extent of colitis. Results Of 1788 patients, 1684 were "tolerant to 5-ASA" while 104 were "intolerant to 5-ASA". Colectomy was performed in 43 (2.6%) of the patients tolerant to 5-ASA and 12 (11.5%) of the patients intolerant to 5-ASA. After adjusting for all covariates, the risk of undergoing colectomy was higher in the "intolerant to 5-ASA" group than in the "tolerant to 5-ASA" group (hazard ratio: 4.92; 95% confidence interval: 2.58-9.38). Conclusion Patients in whom 5-ASA was discontinued due to intolerance had a higher risk of undergoing colectomy than patients tolerant to their first, second or third 5-ASA compounds.