Factors Associated With Response to Rescue Therapy in Acute Severe Ulcerative Colitis

Background Acute severe ulcerative colitis (ASUC) is a medical emergency for which colectomy is required in patients who do not respond to rescue therapy. While previous studies have predominantly focused on predicting outcome to first-line corticosteroid therapy, there is a need to understand the factors associated with response to rescue therapies in order to improve clinical outcomes. We reviewed the evidence regarding factors associated with response to rescue therapy in adults with ASUC and identified future directions for research.Methods A systematic search of the literature was conducted, and 2 reviewers independently assessed studies for inclusion.Results Of 3509 records screened, 101 completed studies were eligible for inclusion. We identified 42 clinical, hematological, biochemical, endoscopic, or pharmacological factors associated with response to rescue therapy. Older age (& GE;50 years), thiopurine experience, and cytomegalovirus or Clostridioides difficile infection were associated with a higher risk of nonresponse to rescue therapy. Biochemical factors associated with poorer response included an elevated C-reactive protein (CRP) & GE;30mg/L on admission, hypoalbuminemia and an elevated ratio of CRP to albumin. Severe endoscopic findings, including a Mayo endoscopic score of 3 or Ulcerative Colitis Endoscopic Index of Severity & GE;5, portended poorer outcomes. The role of fecal calprotectin and therapeutic value of measuring infliximab drug levels in ASUC remain to be defined.Conclusions Response to rescue therapy can be predicted by several specific factors, which would aid clinical decision-making. Existing and emerging factors should be integrated within predictive and prognostic models to help improve clinical outcomes. In this review, we summarize the clinical, hematological, biochemical, radiological, endoscopic, and drug-related factors that predict or are associated with response to rescue therapy in patients with acute severe ulcerative colitis. We also provide a clinical algorithm for clinicians. Graphical Abstract