Rognerud Marit A, Zahl Per-Henrik
Norwegian Institute of Public Health, Division of Epidemiology, Oslo, Norway.
Eur J Public Health. 2006 Feb;16(1):62-8. doi: 10.1093/eurpub/cki070. Epub 2005 Aug 10.
The aim of this paper was to measure socio-economic inequalities in mortality over a 27-year period, and estimate the simultaneous effects of education and income adjusted for changing proportions and potential confounders.
Census data in 1970, 1980 and 1990 with information about income, educational level and household size were linked to mortality records at the individual level and analysed with absolute mortality rates, Poisson regression (univariate and multivariate) and Relative Index of Inequality (RII).
Mortality differences increased between income quartiles and educational groups as well as between singles and non-singles. RII between income quartiles increased from 1.6 to 3.6 for men and 1.7 to 2.7 for women while RII between the educational groups increased from 1.6 to 2.8 for men and 1.5 to 2.1 for women. However, RII derived from the adjusted multivariate regression analysis was 1.8 (men) and 1.9 (women) between the income groups in 1990 and 2.2 (men) and 1.7 (women) between the educational groups. In the 1990s current income was more important than previous income, and the rate ratios (RR) increased for groups dropping into the lowest income quartile between two censuses.
Low education and single status have become relatively more important risk factors for mortality over time. Confounder effects of education and household size could partly explain the seemingly large increase in inequalities between income groups. Results may also indicate a stronger reverse causation (poor health causing low income) over time.
本文旨在衡量27年间死亡率方面的社会经济不平等状况，并估算在比例变化和潜在混杂因素调整后教育与收入的同时效应。
将1970年、1980年和1990年包含收入、教育水平及家庭规模信息的人口普查数据与个体层面的死亡率记录相链接，并采用绝对死亡率、泊松回归（单变量和多变量）以及不平等相对指数（RII）进行分析。
收入四分位数组之间、教育程度组之间以及单身与非单身之间的死亡率差异均有所增加。收入四分位数组之间的RII，男性从1.6增至3.6，女性从1.7增至2.7；而教育程度组之间的RII，男性从1.6增至2.8，女性从1.5增至2.1。然而，经调整的多变量回归分析得出的RII，1990年时收入组之间男性为1.8，女性为1.9；教育程度组之间男性为2.2，女性为1.7。在20世纪90年代，当前收入比先前收入更为重要，且两次人口普查之间落入最低收入四分位数组的人群的率比（RR）有所增加。
随着时间推移，低教育水平和单身状况已成为相对更为重要的死亡风险因素。教育和家庭规模的混杂效应可部分解释收入组之间不平等现象看似大幅增加的情况。结果还可能表明随着时间推移存在更强的反向因果关系（健康状况差导致低收入）。
