Table 1_Exposure to outdoor artificial light at night is associated with a higher risk of ulcerative colitis: a prospective cohort study from the UK Biobank.docx

BackgroundInflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract, and environmental factors are believed to play an important role in its pathogenesis. Exposure to outdoor artificial light at night (ALAN) has been linked to the globally increasing incidence and prevalence of several diseases; however, its relationship with IBD remains unclear. We aimed to estimate the long-term risk of IBD associated with outdoor ALAN exposure in a large-scale prospective cohort.
MethodsWe conducted a large-scale prospective cohort study using the UK Biobank. Outdoor ALAN exposure data were obtained from satellite datasets. The primary outcome was incident IBD. Cox proportional hazards regression was used to examine the association between outdoor ALAN and the incidence risk of IBD, respectively. The non-linear association was further explored using restricted cubic spline (RCS) curves.
ResultsDuring a follow-up period of 13.71 years with 346,163 participants, 1,106 individuals were diagnosed with ulcerative colitis (UC), and 508 developed Crohn’s disease (CD). After adjusting for all covariates, outdoor ALAN exposure levels were positively associated with incident UC, and an 8% higher risk of UC [hazard ratio (HR), 1.084; 95% confidence interval (CI), 1.023–1.149; p < 0.001] was associated with each SD increment of outdoor ALAN exposure. The highest level of ALAN exposure was associated with a significantly increased risk of incident UC compared with the lowest level of exposure. (HR, 1.309; 95% CI: 1.12–1.529; p < 0.001). However, no significant association was observed between outdoor ALAN and CD incidence (HR, 1.044; 95% CI: 0.83, 1.308; p = 0.71). Cubic splines further indicated that outdoor ALAN was non-linearly associated with UC (p for non-linear = 0.0063). Additionally, sensitivity analysis revealed similar results, and subgroup analysis highlighted that the interaction between outdoor ALAN and UC was stronger in women than in men.
ConclusionOur findings provide evidence that a higher ALAN exposure is associated with an increased risk of incident UC, with a significant dose–response relationship, but not with CD. Further studies are needed to elucidate the impact of outdoor ALAN on disease pathogenesis and outcomes.

研究背景：
炎症性肠病（inflammatory bowel disease, IBD）是一类胃肠道慢性炎症性疾病，环境因素被认为在其发病机制中发挥重要作用。夜间户外人工光照（outdoor artificial light at night, ALAN）已被证实与多种疾病的全球发病率和患病率上升相关，但其与炎症性肠病的关联仍不明确。本研究旨在一项大规模前瞻性队列中，评估与夜间户外人工光照暴露相关的炎症性肠病长期发病风险。

研究方法：
本研究基于英国生物库（UK Biobank）开展大规模前瞻性队列研究。夜间户外人工光照暴露数据来源于卫星数据集。本研究的主要结局为炎症性肠病发病。分别采用Cox比例风险回归模型探讨夜间户外人工光照暴露与炎症性肠病发病风险之间的关联，并进一步通过限制性立方样条（restricted cubic spline, RCS）曲线探索二者的非线性关联。

研究结果：
本研究共纳入346163名参与者，随访时长为13.71年。随访期间，共有1106例受试者被诊断为溃疡性结肠炎（ulcerative colitis, UC），508例发展为克罗恩病（Crohn’s disease, CD）。校正所有混杂因素后，夜间户外人工光照暴露水平与溃疡性结肠炎发病呈正相关：夜间户外人工光照暴露每增加1个标准差，溃疡性结肠炎发病风险升高8%[风险比（hazard ratio, HR）=1.084；95%置信区间（confidence interval, CI）：1.023~1.149；P<0.001]。与最低暴露水平组相比，最高暴露水平组的溃疡性结肠炎发病风险显著升高（HR=1.309；95%CI：1.12~1.529；P<0.001）。但未观察到夜间户外人工光照暴露与克罗恩病发病存在显著关联（HR=1.044；95%CI：0.83~1.308；P=0.71）。限制性立方样条分析进一步显示，夜间户外人工光照暴露与溃疡性结肠炎发病存在非线性关联（非线性检验P=0.0063）。此外，敏感性分析得到了一致的研究结果；亚组分析表明，夜间户外人工光照暴露与溃疡性结肠炎的关联在女性群体中强于男性群体。

研究结论：
本研究结果证实，更高的夜间户外人工光照暴露与溃疡性结肠炎发病风险升高存在显著的剂量-反应关系，但与克罗恩病发病无显著关联。未来仍需开展进一步研究，以阐明夜间户外人工光照暴露对疾病发病机制及临床转归的影响。