Clinical risk factors for complicated disease: how reliable are they?

Crohn's disease is a chronic, progressive, destructive disease. Complicated disease can be defined as the presence of bowel damage (stricture, abscess or fistula) and/or the need for surgery. Natural history studies provide invaluable data on the disease course. In population-based cohorts, half of all patients experienced an intestinal complication within 20 years after diagnosis and half of the patients required surgery within 10 years after diagnosis. In Olmsted County, the factors associated with the development of complications were the presence of ileal involvement and perianal disease. The extent of noncolonic disease, current smoking, male gender, penetrating disease behavior and early steroid use were significantly associated with major abdominal surgery. Overall, using various definitions of complicated disease, the predictors of a worse outcome in Crohn's disease were: extensive small bowel disease, severe upper gastrointestinal disease, rectal disease, perianal lesions, early stricturing/penetrating disease, smoking and a young age at diagnosis. Aggressive ulcerative colitis was recently defined as a disease that is associated with a high relapse rate, the need for surgery, the development of colon cancer or the presence of extraintestinal manifestations. About one tenth of patients still require colectomy for ulcerative colitis at 5 years in the era of biologics. An average of 1.6% of patients with ulcerative colitis was diagnosed with colorectal cancer during 14 years of follow-up in population-based cohorts. A younger age at diagnosis and pancolitis were associated with a worse outcome in ulcerative colitis. The identification of clinical risk factors for complicated disease may be used in future disease-modification trials.