Studies on smoking in patients with inflammatory bowel disease and liver transplant recipients

PhD ceremony: Mr. F. van der Heide, 12.45 uur, Aula Academiegebouw, Broerstraat 5, Groningen

Dissertation: Studies on smoking in patients with inflammatory bowel disease and liver transplant recipients

Promotor(s): prof. J.H. Kleibeuker, prof. K.N. Faber

Faculty: Medical Sciences

In this thesis a number of studies on the role of smoking in inflammatory bowel diseases (IBD) and after liver transplantation are described. Smoking has a remarkable opposite effect on IBD; smoking is a risk factor for Crohn’s disease (CD) and protects against ulcerative colitis (UC). In our study the role of active smoking on the development of IBD was confirmed; smoking increased the chance on developing CD and reduced it for UC. However, we could not confirm that active smoking is detrimental for the course of CD. Nevertheless, we found that in CD passive smokers more often needed infliximab and immunosuppressants. In CU we confirmed the beneficial effect of smoking on the disease course and this effect turned out to be dose-dependent. Besides smoking, the genetic background of the patient also has an important influence on the development of IBD. During the last decade many genetic variants were found to be associated with IBD, especially CD. We found a difference in associated genes between smoking and non-smoking CD patients. This implies a complex gene–environment interaction in CD.

The role of smoking after liver transplantation was also studied. Cardiovascular diseases and malignancies are important problems after transplantation. Both are associated with smoking, but the smoking behaviour of liver transplant recipients is scarcely studied. We found a high and constant percentage of smokers before and after transplantation, many former smokers who restarted smoking, and a striking increased number of malignancies in smokers (13% versus 2%). We plead for a smoking intervention program and regular screening for malignancies.