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P229. Environmental and clinical risk factors for severe Crohn's disease

N. Azzopardi1, P. Ellul1, S. Chetcuti1, G. Laferla2, 1Mater Dei Hospital, Gastroenterology, Tal Qroqq, Malta, 2University of Malta, Medicine & Surgery, Tal Qroqq, Malta


Severe Crohn's disease (CD) may be defined as stricturing or fistulating disease, disease requiring surgery secondary to CD complications and disease requiring dual immunosuppression with both anti-TNF-α inhibitors and purine analogue therapy for maintenance of remission. Smoking cessation has been shown to decrease the risk of surgery and the risk of developing stricturing or fistulating disease [1]. Young age of Crohn's disease onset has also been shown to be associated with increased requirements of biological therapy [2].


101 patients with a histological diagnosis of Crohn's disease were recruited. Demographic characteristics, smoking history and age of disease onset of these patients were entered into a database.


21 patients (20.8%) underwent bowel surgery because of Crohn's disease complications, 70 patients (69.3%) had non-stricturing, non-penetrating disease, 24 patients (23.8%) had stricturing disease and 7 patients (6.9%) had penetrating disease. 28 patients (27.7%) were on dual immunosuppression with azathioprine and infliximab and 10 patients (9.9%) on dual immunosuppression had also undergone surgery. These markers of disease severity were analysed against environmental risk factors.

Smoking was associated with an increased risk of requiring both dual immunosuppression and surgical intervention (P: 0.017). Male gender was associated with an increased risk of surgical intervention (P: 0.013) while young age of Crohn's disease onset (age <21 years) was associated with an increased risk of surgical intervention (P: 0.006) and requirement of dual immunosuppressant therapy with (P: 0.04) and without surgery (P: 0.006).

Table: Environmental and clinical risk factors for severe Crohn's disease
Surgery (n = 21)Stricturing disease (n = 24)Penetrating disease (n = 7)Dual immuno-suppressants (n = 28)Dual immuno-suppressants + Surgery (n = 10)
Smokers (n = 26)8 (30.7%)8 (30.7%)3 (11.5%)9 (34.6%)6 (23.1%)
Non-smokers (n = 75)13 (17.3%)16 (21.3%)4 (5.3%)19 (12%)4 (5.3%)
Male gender (n = 51)16 (31.3%)13 (25.5%)5 (9.8%)16 (31.3%)7 (13.7%)
Female gender (n = 50)5 (10%)11 (22%)2 (4%)12 (24%)3 (6%)
Age at diagnosis <21 years (n = 23)10 (43.5%)6 (26.1%)2 (8.6%)12 (52.1%)5 (21.7%)
Age at diagnosis >21 years (n = 78)11 (14.1%)18 (23.1%)5 (6.4%)16 (20.5%)5 (6.4%)


Smoking, male gender and young age of disease onset are markers of severe CD. Smoking is a modifiable environmental agent and smoking cessation should be actively encouraged [3].

1. Lawrance IC, Murray K, Batman B, Gearry RB, Grafton R, Krishnaprasad K, Andrews JM, Prosser R, Bampton PA, Cooke SE, Mahy G, Radford-Smith G, Croft A, Hanigan K, (2013), Crohn's disease and smoking: is it ever too late to quit?, J Crohns Colitis, S1873-9946(13)00200–6.

2. Feagins LA, Spechler SJ. (2010), Biologic agent use varies inversely with age at diagnosis in Crohn's disease., Dig Dis Sci, 55(11): 3164–70.

3. Lakatos PL, Vegh Z, Lovasz BD, David G, Pandur T, Erdelyi Z, Szita I, Mester G, Balogh M, Szipocs I, Molnar C, Komaromi E, Golovics PA, Mandel M, Horvath A, Szathmari M, Kiss LS, Lakatos L., (2013), Is current smoking still an important environmental factor in inflammatory bowel diseases? Results from a population-based incident cohort., Inflamm Bowel Dis, Apr; 19(5): 1010–7.