Editing Ulcerative colitis (section)

===Progression or remission===
People with ulcerative colitis usually have an intermittent course, with periods of disease inactivity alternating with "flares" of disease. People with proctitis or left-sided colitis usually have a more benign course: only 15% progress proximally with their disease, and up to 20% can have sustained remission in the absence of any therapy. A subset of people experience a course of disease progress rapidly. In these cases, there is usually a failure to respond to medication and surgery often is performed within the first few years of disease onset.<ref>{{cite journal | vauthors = Kevans D, Murthy S, Mould DR, Silverberg MS | title = Accelerated Clearance of Infliximab is Associated With Treatment Failure in Patients With Corticosteroid-Refractory Acute Ulcerative Colitis | journal = Journal of Crohn's & Colitis | volume = 12 | issue = 6 | pages = 662–669 | date = May 2018 | pmid = 29659758 | doi = 10.1093/ecco-jcc/jjy028 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Horio Y, Uchino M, Bando T, Chohno T, Sasaki H, Hirata A, Takesue Y, Ikeuchi H | title = Rectal-sparing type of ulcerative colitis predicts lack of response to pharmacotherapies | journal = BMC Surgery | volume = 17 | issue = 1 | pages = 59 | date = May 2017 | pmid = 28526076 | pmc = 5437574 | doi = 10.1186/s12893-017-0255-5 | doi-access = free }}</ref> People with more extensive disease are less likely to sustain remission, but the rate of remission is independent of the severity of the disease.<ref>{{cite book |doi=10.1016/B978-1-4160-6189-2.00112-8 |chapter=Ulcerative Colitis |title=Sleisenger and Fordtran's Gastrointestinal and Liver Disease |year=2010 |last1=Osterman |first1=Mark T. |last2=Lichtenstein |first2=Gary R. |pages=1975–2013.e9 |isbn=9781416061892 }}</ref> Several risk factors are associated with eventual need for colectomy, including: prior hospitalization for UC, extensive colitis, need for systemic steroids, young age at diagnosis, low serum albumin, elevated inflammatory markers (CRP & ESR), and severe inflammation seen during colonoscopy.<ref name=AGAClinicalPractice2020 /><ref name=ACG_Guidelines_2019 /> Surgical removal of the large intestine is necessary in some cases.<ref name=ACG_Guidelines_2019 />