Does the initial location of Crohn's disease have an influence on the time-to-relapse in patients under maintenance treatment with oral mesalamine?

The aim of this study was to determine the possible influence of the initial location of Crohn's disease (CD) on the time-to-relapse in patients with quiescent CD treated only with oral mesalamine (5-ASA). We divided 74 consecutive patients in clinical remission into three groups according to the initial location of CD. Group A consisted of 30 cases with an ileal location; group B, 18 with ileocolonic location; and group C, 26 with a colonic location. The patients entered the study if they were in clinical and endoscopic remission for at least 3 months. Relapse was defined by CD Activity Index > or = 150, CD Endoscopic Index of Severity > or =4, and by an abnormal increase of C-reactive protein, white blood cell count, and erythrocyte sedimentation rate; moreover, if it was confirmed by x-ray and/or endoscopy. Time-to-relapse was defined as the interval between the date of enrollment and the date of relapse. The patients with an ileal location showed a relapse within 5 years, with a time-to-relapse of 1 year in 26% of cases, 2 years in 85%, 3 years in 92%, and 4 years in 96%. The patients with ileocolonic location showed a relapse within 4 years, with time-to-relapse of 1 year in 39% of cases, 2 years in 89%, and 3 years in 94%. The cases with a colonic location showed a relapse within 6 years, with time-to-relapse of 1 year in 33% of cases, 2 years in 71%, 3 years in 79%, and 4 years in 87%. Surgical treatment was necessary in 37% of the cases with an ileal location, in 44% with ileocolonic location, and 17% with a colonic location. In conclusion, even if our data lack a statistical significance, we have found that the initial anatomic involvement is not a valid parameter to predict the relapse risk in a homogeneous group under continuous treatment with oral 5-ASA, although ileocolonic location seems to have a more aggressive course.