Rust George, Zhang Shun, Yu Zhongyuan, Caplan Lee, Jain Sanjay, Ayer Turgay, McRoy Luceta, Levine Robert S
Department of Behavioral Sciences and Social Medicine, Florida State University College of Medicine, Tallahassee, FL.
Department of Community Health And Preventive Medicine, Morehouse School of Medicine, Atlanta, Georgia.
Cancer. 2016 Jun 1;122(11):1735-48. doi: 10.1002/cncr.29958. Epub 2016 Mar 11.
Although colorectal cancer (CRC) mortality rates are declining, racial-ethnic disparities in CRC mortality nationally are widening. Herein, the authors attempted to identify county-level variations in this pattern, and to characterize counties with improving disparity trends.
The authors examined 20-year trends in US county-level black-white disparities in CRC age-adjusted mortality rates during the study period between 1989 and 2010. Using a mixed linear model, counties were grouped into mutually exclusive patterns of black-white racial disparity trends in age-adjusted CRC mortality across 20 three-year rolling average data points. County-level characteristics from census data and from the Area Health Resources File were normalized and entered into a principal component analysis. Multinomial logistic regression models were used to test the relation between these factors (clusters of related contextual variables) and the disparity trend pattern group for each county.
Counties were grouped into 4 disparity trend pattern groups: 1) persistent disparity (parallel black and white trend lines); 2) diverging (widening disparity); 3) sustained equality; and 4) converging (moving from disparate outcomes toward equality). The initial principal component analysis clustered the 82 independent variables into a smaller number of components, 6 of which explained 47% of the county-level variation in disparity trend patterns.
County-level variation in social determinants, health care workforce, and health systems all were found to contribute to variations in cancer mortality disparity trend patterns from 1990 through 2010. Counties sustaining equality over time or moving from disparities to equality in cancer mortality suggest that disparities are not inevitable, and provide hope that more communities can achieve optimal and equitable cancer outcomes for all. Cancer 2016;122:1735-48. © 2016 American Cancer Society.
尽管结直肠癌（CRC）死亡率正在下降，但全国范围内CRC死亡率的种族差异却在扩大。在此，作者试图确定这种模式在县级层面的差异，并对差异趋势有所改善的县进行特征描述。
作者研究了1989年至2010年研究期间美国县级CRC年龄调整死亡率的黑白差异的20年趋势。使用混合线性模型，根据20个三年滚动平均数据点的年龄调整CRC死亡率，将各县分为黑白种族差异趋势的相互排斥模式。对人口普查数据和地区卫生资源文件中的县级特征进行归一化处理，并将其纳入主成分分析。使用多项逻辑回归模型来检验这些因素（相关背景变量的聚类）与每个县的差异趋势模式组之间的关系。
各县被分为4个差异趋势模式组：1）持续差异（黑白趋势线平行）；2）分歧（差异扩大）；3）持续平等；4）趋同（从不同结果走向平等）。最初的主成分分析将82个独立变量聚类为数量较少的成分，其中6个成分解释了县级差异趋势模式中47%的变化。
从1990年到2010年，社会决定因素、医疗保健劳动力和卫生系统的县级差异都被发现导致了癌症死亡率差异趋势模式的变化。随着时间的推移保持平等或在癌症死亡率方面从差异走向平等的县表明，差异并非不可避免，并为更多社区能够为所有人实现最佳和公平的癌症治疗结果带来了希望。《癌症》2016年；122:1735 - 48。©2016美国癌症协会。
