Crohn’s disease (CD), a type of inflammatory bowel disease (IBD), is currently defined as idiopathic due to its largely unknown etiology. A chronic disease which affects the gastrointestinal tract, it’s thought to be multifaceted, involving multiple genetic and environmental factors. Rates of IBD are different across geography, time, age, and smoking, lending credence to the idea that the environment plays a role in disease pathogenesis. Out of all these factors, however, smoking and appendectomy (surgical removal of the vermiform appendix) are the most significantly correlated, with smoking being especially correlated for CD.
Smokers, in addition to having a decreased antioxidant capacity, show an increased production of reactive oxygen species. Some evidence exists that the tobacco glycoprotein is capable of promoting a Th1 cell response, which may lead to further inflammatory problems in patients with CD. The extent that smoking worsens CD-related symptoms appears to be dose-dependent: 48% intestinal inflammatory activity was reported for heavy smokers (> 10 cigarettes/day), 46% for moderate smokers (< 10 cigarettes/day), and 37% among non-smokers. Patients who smoke tend to require more aggressive treatment (higher doses of immunosuppressants and CD-specific drugs) and patients who stop smoking show a significantly lower relapse risk.
Despite the availability of anti-inflammatory drugs and other biological tools, intestinal resection remains one of the primary forms of treatment for those with CD. Patients suffering from CD have a 40-60% chance of undergoing an intestinal resection within five-ten years of disease diagnosis. Unfortunately, return of the disease post-resection is still very common, requiring additional surgeries (referred to as surgical recurrence). Patients who undergo this procedure to treat their ileal disease are significantly more likely to require surgical recurrence if they smoke or chew tobacco. Another study retrospectively analyzed 182 CD patients who had undergone an intestinal resection and found that smoking was an independent risk factor for surgical recurrence as well as endoscopic lesions.
How smoking affects the therapeutic response of CD patients seems to be dependent on the type of treatment. For example, no relationship was found between smoking and a patient’s response to infliximab (monoclonal antibody against tumour necrosis factor alpha). Smoking adversely affects a patient’s response to thiopurine, however, decreasing the efficacy of the treatment and increasing the drug’s side effects [1].
In sum, I think it’s quite apparent that smoking worsens CD-related symptoms, creating a demand for more aggressive treatment and decreasing the chance of disease remission.
Citations:
1. Nos P, Domènech E. Management of Crohn’s disease in smokers: Is an alternative approach necessary? World Journal of Gastroenterology 2011; 17: 3567-3574.
While trying to find more research gong more in depth on why smoking puts people with Crohn’s disease at a higher risk I found an article that studied at which points during the year patients have more symptoms. The study lasted from 1995 to 2004 and looked at reported symptoms associated with the disease. The researchers found that Crohn’s Disease symptoms occurred more frequently during the spring and summer than during autumn and winter. In a very small part of the discussion the authors mentioned smoking and they stated that “cigarette sales and onset of smoking peak in the summer months…” [1]. It would be interesting to test how smoking would exacerbate the effects of other factors.
ReplyDelete1. Aratari, C. Papi, B. Galletti, E. Angelucci, A. Viscido, V. D’Ovidio, A. Ciaco, M. Abdullahi, R. Caprilli, Seasonal variations in onset of symptoms in Crohn's disease, Digestive and Liver Disease, Volume 38, Issue 5, May 2006, Pages 319-323, ISSN 1590-8658, 10.1016/j.dld.2005.10.002.
(http://www.sciencedirect.com/science/article/pii/S1590865805004226)
That is very cool! It would be interesting to see if cigarette sales are also higher during the spring and lower in the autumn and winter. If so, that observation could potentially be explained by changing smoking habits with changing seasons.
ReplyDeleteYeah, this is definitely a great point! It would be very interesting to find out more about that correlation. I was also doing some research on the impact of smoking on Crohn's and found some pretty interesting statistics! Apparently, in one study that was done with CD patients who were continued smokers and those who had quit smoking it was determined that those who had quit smoking for more than a year had 65% fewer pain flare-ups than continued smokers. That's definitely a huge percentage and also something that all smokers with CD should be informed about. Another fact I found really fascinating is that in this study when the researchers compared the group of quitters to a group of Crohn's patients who had never smoked in the first place, they found the groups had a similar number of disease flare-ups.
ReplyDeletehttp://www.webmd.com/smoking-cessation/news/20010416/fight-fire-of-crohns-disease-quit-smoking
I found an interesting article that discusses the seasonality of cigarette sales and the factors that influence them. This article confirmed that tobacco sales are highest in summer and lowest in winter. It discussed how social and political factors can account for this trend. For example, the wide spread ban on indoor smoking makes smoking in the winter time difficult. Also the timing of new taxes on tobacco are implemented has an effect on sales.
ReplyDeletehttp://tobaccocontrol.bmj.com/content/12/1/105.full
AdrijanaK495:
ReplyDelete65% fewer pain flare-ups is highly significant. This is just further evidence that patients with CD should avoid smoking.
RebekkaL495:
That's a very interesting explanation for why smoking is lowest in the winter. It definitely makes sense too - I'm sure smoking is less appealing if it involves getting frozen outside.