*Pôle pharmaceutique, Centre Hospitalo-Universitaire, Besançon France, France.
Inflamm Bowel Dis. 2010 May;16(5):813-21. doi: 10.1002/ibd.21122.
In a previous study we found a north-south gradient for Crohn's disease (CD) incidence in France. The aim of the present study was to determine if socioeconomic factors may influence the geographic distribution of CD and ulcerative colitis (UC) in France.
Using the national health insurance databases, incidence rates of CD and UC were estimated for each of 341 metropolitan "job areas" in 2000-2002. Relationships between incidence rates and relevant contextual variables from the 1999 French census were tested for significance using a Poisson regression. Mapping of smoothed relative risks (sRR) for CD and UC at the scale of job areas, using a Bayesian approach and adjusting for significant contextual variables, was carried out in order to search for geographic variations.
CD incidence rates were negatively related to the percentage of farmers and to the percentage of housing with bathroom and toilets and positively related to the unemployment rate and to the percentage of households below the poverty threshold. Mapping of sRR for CD showed a clear north-south gradient, which was slightly improved after including the percentage of farmers and the percentage of housing with toilets. In UC we found no significant correlation between either incidence and socioeconomic variables or incidence and house equipment variables, and there was no north-south gradient. However, there was a positive and significant correlation between CD and UC incidence.
The present study shows that geographic risk factors of CD in France are northern latitude, nonrural areas, and areas with poor sanitary house equipment. Among these factors the most important is northern latitude.
在之前的一项研究中，我们发现法国的克罗恩病（CD）发病率呈南北梯度分布。本研究的目的是确定社会经济因素是否会影响法国 CD 和溃疡性结肠炎（UC）的地理分布。
利用国家健康保险数据库，估计了 2000-2002 年 341 个大都市“工作区”中每一个的 CD 和 UC 的发病率。使用泊松回归，测试发病率与 1999 年法国人口普查的相关背景变量之间的关系是否显著。使用贝叶斯方法，对 CD 和 UC 的相对风险（RR）进行平滑映射，并调整了显著的背景变量，以寻找地理变化。
CD 的发病率与农民的比例呈负相关，与带浴室和厕所的住房比例呈负相关，与失业率和低于贫困线的家庭比例呈正相关。CD 的 RR 映射显示出明显的南北梯度，在包括农民比例和带厕所的住房比例后，梯度略有改善。在 UC 中，我们发现发病率与社会经济变量或发病率与房屋设备变量之间没有显著的相关性，也没有南北梯度。然而，CD 和 UC 的发病率之间存在正相关。
本研究表明，法国 CD 的地理风险因素是北纬、非农村地区和卫生房屋设备较差的地区。在这些因素中，最重要的是北纬。
