P263. Definition of phenotypic characteristics of late onset IBD
A. McNichol1, S. Din1, M. Porteous1, C. Lees1, J. Satsangi2, I. Arnott1, 1NHS Lothian, GI Unit, Edinburgh, United Kingdom, 2University of Edinburgh, GI Unit, Edinburgh, United Kingdom
Categorisation of disease guides individualised therapeutic strategies and predicts response and prognosis. The Montreal classification of the inflammatory bowel diseases divides Crohns disease and ulcerative colitis into multiple sub-phenotypes. Rigorous analysis of phenotypic characteristics demonstrated that paediatric IBD varied significantly with that of the adult population; resulting in a defined age category for paediatric IBD. Similarly, late onset IBD may indicate a lower genetic preponderance and less aggressive disease behaviour.
Patients diagnosed with IBD over the age of 40 were identified; 206 had Crohns disease and 306 ulcerative colitis. Phenotypic characteristics, disease progression and response to therapy were assessed at diagnosis and at 5 year follow up. The A3 category was subdivided into A3 40–59 years at diagnosis and a new category, A4 ≥60 years at diagnosis, was created. Fishers' exact test was used to compare categorical data.
Crohn's disease: At diagnosis 67% were 40–59 years and 29% had an age of onset >60 years. Females were observed more frequently in the >60 years category, 83.1% v 61.8%, (OR 2.29, p = 0.0043) than in those 40–59 years at diagnosis. Colonic involvement was more common in the >60 years, 64% v 36%, (OR 1.84, p = 0.0023) whereas ileocolonic disease presented more frequently 19.5% v 3.4%, (OR 1.69, p = 0.0049) in the 40–59 years and >60 years, respectively. Ulcerative Colitis: Two thirds (204/306) were categorised into 40–59 years and one third had an age of onset >60 years. Proctitis/E1was observed more frequently in the 40–59 years group 34.3% v 19.6% (OR 0.59, p = 0.0078.) Pan-colonic disease was more common >60 years old, 34.3% v 22.6%, than in 40–59 year category. In either group there was no difference in disease progression or surgical intervention at 5 year follow up.
Late onset IBD constitutes a third of patients in the current A3 Montreal category. Late onset Crohns' disease is characterised by more frequent colonic involvement. Late onset ulcerative colitis has a higher burden of pan-colonic disease. These observations may reflect a lower genetic burden and a less aggressive disease process in elderly patients. The results would suggest that a new “A4” classification for elderly-onset disease identified at >60 years would be a logical sub categorisation in the phenotypic classification of IBD.