School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada.
Air Health Sciences Division, Health Canada, Ottawa, Canada.
Am J Gastroenterol. 2021 Feb 1;116(2):347-353. doi: 10.14309/ajg.0000000000000990.
Environmental factors related to urbanization and industrialization are believed to be involved in inflammatory bowel disease (IBD) development, but no study has looked at the association between greenspace and IBD.
We conducted a retrospective cohort study using linked population-based health administrative and environmental data sets. The study population comprised 2,715,318 mother-infant pairs from hospital births in Ontario, Canada, between April 1, 1991, and March 31, 2014. We measured the exposure to residential greenspace using the normalized difference vegetation index derived using remote-sensing methods. Average greenspace was estimated for the pregnancy and childhood periods. We used mixed-effects Cox proportional hazard models to assess potential associations between residential greenspace and the risk of developing IBD before 18 years while adjusting for covariates including sex, maternal IBD, rural/urban residence at birth, and neighborhood income.
There were 3,444 IBD diagnoses that occurred during follow-up. An increase in the interquartile range of residential greenspace during the childhood period was associated with a lower risk of developing pediatric-onset IBD (hazard ratio [HR] 0.77, 95% confidence interval [CI] 0.74-0.81). This relationship was significant for both ulcerative colitis (HR 0.72 95% CI 0.67-0.78) and Crohn's disease (HR 0.81, 95% CI 0.76-0.87). There was a linear dose response across increasing quartiles of greenspace (P < 0.0001). No consistent association was detected between maternal intrapartum greenspace exposure and pediatric-onset IBD.
Higher exposure to residential greenspace during childhood was associated with a reduced risk of IBD, suggesting a novel avenue to prevent IBD in children.
城市化和工业化相关的环境因素被认为与炎症性肠病（IBD）的发展有关，但目前尚无研究探讨绿地与 IBD 之间的关联。
我们开展了一项回顾性队列研究，使用了基于人群的健康管理和环境数据集进行分析。研究人群为加拿大安大略省 1991 年 4 月 1 日至 2014 年 3 月 31 日期间在医院分娩的 2715318 对母婴。我们使用基于遥感方法得出的归一化差异植被指数来测量住宅绿地的暴露情况。对妊娠和儿童期的平均绿地面积进行了估计。我们使用混合效应 Cox 比例风险模型，在调整了性别、母亲 IBD、出生时的农村/城市居住地以及邻里收入等混杂因素后，评估了住宅绿地与 18 岁前发生 IBD 风险之间的潜在关联。
在随访期间，共发生了 3444 例 IBD 诊断。儿童期住宅绿地面积增加一个四分位间距与发生儿童期发病的 IBD 的风险降低相关（风险比 [HR] 0.77，95%置信区间 [CI] 0.74-0.81）。这种关联在溃疡性结肠炎（HR 0.72，95% CI 0.67-0.78）和克罗恩病（HR 0.81，95% CI 0.76-0.87）中均有意义。随着绿地四分位间距的增加，存在线性剂量反应关系（P < 0.0001）。产妇产时绿地暴露与儿童发病的 IBD 之间未发现一致的关联。
儿童期住宅绿地暴露量较高与 IBD 风险降低相关，提示了预防儿童 IBD 的新途径。
