The effect modification of occupational social class in the association between sex and type 2 diabetes: results from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

We evaluated data from 14,156 baseline participants of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) collected from 2008 to 2010, to analyze the effect modification of occupational social class on the association between sex and prevalence of type 2 diabetes. The crude and age-adjusted prevalence, according to sex and occupational social class, were estimated using generalized linear models with binomial distribution and logarithmic link function. This model was also used to estimate prevalence ratios (PR), adjusting for age group, race/skin color, and maternal education. The effect modification was measured in the multiplicative and additive scales. Males had higher crude and age-adjusted prevalence in all occupational social class strata. As occupational social class increases, the prevalence among males and females decreases. The PR of males to females decreased according to occupational class: 66% (PR = 1.66; 95%CI: 1.44; 1.90), 39% (PR = 1.39; 95%CI: 1.02; 1.89), and 28% (PR = 1.28; 95%CI: 0.94; 1.75) in the high, middle, and low occupational social classes, respectively. We found an inverse effect of the occupational social class on the association between sex and type 2 diabetes on the multiplicative scale, suggesting that it acts as an effect modifier.

本研究纳入巴西成人健康纵向研究（Brazilian Longitudinal Study of Adult Health，ELSA-Brasil）2008至2010年收集的14156名基线参与者数据，旨在分析职业社会阶层对性别与2型糖尿病患病率之间关联的效应修正作用。
本研究采用服从二项分布、设置对数连接函数的广义线性模型，按性别与职业社会阶层估算粗患病率与年龄校正患病率；同时利用该模型校正年龄组、种族/肤色及母亲受教育程度，估算患病率比（Prevalence Ratio，PR）。
本研究从相乘尺度与相加尺度两个维度测量效应修正作用。
结果显示：在所有职业社会阶层分层中，男性的粗患病率与年龄校正患病率均更高；随着职业社会阶层提升，男性与女性的糖尿病患病率均呈下降趋势。
男性与女性的患病率比随职业阶层升高而降低：在高、中、低职业社会阶层中，该比值分别为1.66（95%置信区间（95% Confidence Interval）：1.44~1.90）、1.39（95%置信区间：1.02~1.89）及1.28（95%置信区间：0.94~1.75），对应男性较女性的患病率优势分别为66%、39%及28%。
本研究在相乘尺度上发现职业社会阶层对性别与2型糖尿病之间的关联存在反向修饰作用，提示职业社会阶层可作为该关联的效应修正因子。