The study of the effectiveness of maintenance treatment with infliximab for ulcerative colitis patients who respond to induction treatment with infliximab

INTERVENTION: Patients in maintenance group receive intravenous infusion of infliximab (5mg/kg) at week 0, 2, and 6 and then every 8 weeks (up to week 54). Patients in discontinuation group receive intravenous infusion of infliximab (5mg/kg) at week 0, 2, and 6 (not receiving infliximab at week 14, 22, 30, 38, 46 and 54). CONDITION: ulcerative colitis PRIMARY OUTCOME: Remission rate at week 54 SECONDARY OUTCOME: 1) The rate of remission (Mayo score of 0‐2, with each individual subscore of 0‐1) at week 8 and 30; 2) The rate of clinical response (a decrease in the total Mayo score of at least 3 points and at least 30%, with a decrease in the subscore for rectal bleeding of at least 1 point or an absolute subscore for rectal bleeding of 0 or 1) at week 8, 30 and 54; 3) The rate of mucosal healing at week 8, 30 and 54; 4) Safety assessment; etc. INCLUSION CRITERIA: Eligible patients have active ulcerative colitis with a Mayo score of 6 to 12 points and moderate‐to‐severe active disease on sigmoidoscopy (Mayo endoscopic subscore of at least 2) despite concurrent treatment with 5‐aminosalicylates, corticosteroids, azathioprine or 6‐mercaptopurine at week 0, and have a clinical response to infliximab at week 8.