Abstract ID: A110
1. Community Health Sciences , University of Calgary, Calgary, AB, Canada; 2. Medicine and Community Health Sciences, University of Calgary, Calgary, AB, Canada; 3. Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
Background: Anti-tumour necrosis factor alpha (TNF) therapies including infliximab, adalimumab and certolizumab, have been proven to be effective for the induction of response and remission in patients with Crohn’s disease. Smoking, a modifiable factor, has been demonstrated to have a negative influence on disease activity.
Aims: We conducted a systematic review and meta-analysis to examine the association between smoking status and clinical outcomes (remission and response) in individuals with Crohn's disease treated with anti-TNF therapies.
Methods: MEDLINE, EMBASE and PubMED were searched from inception to July 2016. References and conference abstracts were searched to identify additional studies. We included observational studies that reported smoking status and clinical outcomes (remission and response) related to the use of anti-TNF therapies in patients with Crohn’s disease. Study selection and data extraction were performed by two independent reviewers. Methodological quality was assessed using modified version of the Newcastle Ottawa Scale. The primary outcome was remission and defined as less than 150 CDAI points or less than 4 HBI points. The secondary outcome was response and defined as a reduction of 70 CDAI points or decrease of 3 or more HBI points. Risk ratios (RR) and 95% confidence intervals (95% CI) were calculated. Meta-analysis was used to pool the relative risk from identified studies with a random effects model.
Results: Of the 1211 studies reviewed for eligibility and data extraction, we included fifteen observational studies in the final meta-analysis. There was no statistically significant association between smoking and induction of remission (RR: 0.77; 95% CI: 0.56 to 1.05) and response (RR: 0.96; 95% CI: 0.89 to 1.03) to infliximab and adalimumab. Subgroup analysis were conducted to determine the source of heterogeneity. Prior exposure to anti-TNF therapies, type of anti-TNF therapies (infliximab vs. adalimumab), and disease behaviour (luminal vs. fistulising) was not a source of heterogeneity.
Conclusions: Smoking did not have a significant effect on the induction of clinical response or remission in patients with Crohn’s disease that were treated with anti-TNF therapies. Clinicians should therefore not base their decision to use anti-TNF therapies, such as infliximab and adalimumab, in patients with Crohn’s disease solely on the individual’s smoking status.
Figure 1. Relative risk ratio for response to anti-TNF therapies (infliximab or adalimumab) in smokers compared to non-smokers in twelve studies