We speculated that the cumulative operation rate may be affected by differences Pexidartinib cost in recruitment, patient characteristics, and environmental factors in each study in addition to ethnic differences. This study found that stricturing and penetrating disease behavior at diagnosis have an impact on the need for CD-related surgery. In addition, the HR for current and former smoking at the time of diagnosis was 1.86 and 1.78, respectively, which confirmed the harmful effect of smoking on the natural course of CD in earlier reports.[41-43] With regards to predictive factors for surgery, our results are in

agreement with a study of Chinese patients,[37] whereas a study of Japanese patients identified female gender and ileal involvement as independent predictors for surgery.[44] Meanwhile, the environmental factors related to CD Selleck Fostamatinib include cigarette smoking, and smoking has been reported to accelerate the disease course and increase the risk of recurrence or reoperation in CD patients.[41-43] Our results call attention to the importance of encouraging CD patients to cease smoking and seek out smoking cessation programs. With respect to immunosuppressive or biological agents, we identified younger age (< 40 years), ileal involvement, and perianal disease at diagnosis as significant overlapped independent predictors of need for these

medications. In the multivariate analyses, UGI disease was predictive of need for immunosuppressants, while penetrating disease behavior was predictive of a need for infliximab. These variables have been reported to be clinical predictors of an unfavorable course of CD in earlier studies.[17-21] Among them, age < 40 years[17, 20, 21] and perianal disease[17, 18] at the time of diagnosis have been identified to be predictive of developing subsequent disabling ADAMTS5 disease and the need for first surgery. Of note, however, these two clinical factors were not independent predictors for the first CD-related surgery in our study. Several factors can be considered as the cause of this finding. As for the age at diagnosis, younger

CD patients tended to be prescribed immunosuppressive and biological agents more often compared with older patients. In the present study, immunosuppressants and biologics were used in 70.5% and 29.7% of patients < 40 years of age, respectively, whereas these medications were used in 37.7% and 13.1% of patients ≥ 40 years, respectively. Likewise, these therapeutic agents were also used more commonly in CD patients with perianal disease because of their efficacy in this condition.[45-47] Considering that these agents are effective for maintaining remission of CD,[48-50] more frequent use in patients with younger age or perianal disease may influence results of predictors for first CD-related surgery. The present study has several limitations. First, this was a hospital-based cohort study. Thus, compared with population-based cohorts, it may overestimate characteristics in patients with severe disease.