Department of Surgery, Johns Hopkins University, Baltimore, MD, USA.
Department of Gastroenterology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
Dig Dis Sci. 2018 Oct;63(10):2703-2713. doi: 10.1007/s10620-018-5142-0. Epub 2018 Jun 4.
Cigarette smoking is thought to increase the risk of Crohn's disease (CD) and exacerbate the disease course, with opposite roles in ulcerative colitis (UC). However, these findings are from Western populations, and the association between smoking and inflammatory bowel disease (IBD) has not been well studied in Asia.
We aimed to compare the prevalence of smoking at diagnosis between IBD cases and controls recruited in China, India, and the USA, and to investigate the impact of smoking on disease outcomes.
We recruited IBD cases and controls between 2014 and 2018. All participants completed a questionnaire about demographic characteristics, environmental risk factors and IBD history.
We recruited 337 participants from China, 194 from India, and 645 from the USA. In China, CD cases were less likely than controls to be current smokers (adjusted odds ratio [95% CI] 0.4 [0.2-0.9]). There was no association between current or former smoking and CD in the USA. In China and the USA, UC cases were more likely to be former smokers than controls (China 14.6 [3.3-64.8]; USA 1.8 [1.0-3.3]). In India, both CD and UC had similar current smoking status to controls at diagnosis. Current smoking at diagnosis was significantly associated with greater use of immunosuppressants (4.4 [1.1-18.1]) in CD cases in China.
We found heterogeneity in the associations of smoking and IBD risk and outcomes between China, India, and the USA. Further study with more adequate sample size and more uniform definition of smoking status is warranted.
吸烟被认为会增加克罗恩病（CD）的风险并加重疾病进程，而在溃疡性结肠炎（UC）中则起到相反的作用。然而，这些发现来自于西方人群，吸烟与炎症性肠病（IBD）之间的关联在亚洲尚未得到很好的研究。
我们旨在比较在中国、印度和美国招募的 IBD 病例和对照者在诊断时的吸烟患病率，并探讨吸烟对疾病结局的影响。
我们在 2014 年至 2018 年期间招募了 IBD 病例和对照者。所有参与者都完成了一份关于人口统计学特征、环境风险因素和 IBD 病史的问卷。
我们在中国招募了 337 名参与者，在印度招募了 194 名，在美国招募了 645 名。在中国，CD 病例中当前吸烟者的比例低于对照组（调整后的优势比[95%CI]为 0.4 [0.2-0.9]）。在美国，当前或曾经吸烟与 CD 之间没有关联。在中国和美国，UC 病例中曾经吸烟者的比例高于对照组（中国 14.6 [3.3-64.8]；美国 1.8 [1.0-3.3]）。在印度，CD 和 UC 病例在诊断时的当前吸烟状况与对照组相似。在中国，CD 病例在诊断时的当前吸烟与更频繁地使用免疫抑制剂有关（4.4 [1.1-18.1]）。
我们发现吸烟与 IBD 风险和结局之间的关联在中、印、美三国存在异质性。需要进一步研究，样本量更大，吸烟状况的定义更统一。
