School of Public Health, University of California, Berkeley, CA 94704, USA.
Cancer Epidemiol. 2012 Feb;36(1):36-44. doi: 10.1016/j.canep.2011.05.005. Epub 2011 Oct 21.
Although selection bias in case-control studies has been studied extensively, little is known about selection of cases and controls among various ethnic groups. This study compares racial differences in childhood cancer rates as estimated by case-control studies with various design features. It also compares estimates of racial distribution among cases as reported by case-control studies to those observed for an ideal case series with complete ascertainment of cases for these studies or in population-based cancer registries in corresponding geographic regions and calendar periods.
Peer-reviewed publications on childhood leukemia and brain tumors from North America, published between 1980 and 2007, were reviewed. Incidence data by race/ethnicity were compiled from research publications, federal cancer statistics, and cancer registries. Meta-analysis was conducted to assess racial/ethnic differences by study characteristics. Racial distributions of cases from published case-control studies were compared to those of a presumably noncensored case distribution (i.e. include both participating and non-participating cases in a case-control study) or cases recorded by cancer registries.
In interview-based case-control studies of childhood cancer, the proportion of Whites compared to non-Whites tended to be higher among controls than among cases; however, the opposite was true for record-based case-control studies. Additionally, the proportion of Whites tended to be higher among the participating cases in the published case-control studies compared to the proportion of Whites among the non-participating cases or in cancer registries.
Investigators need to consider differential participation by racial group as a potential source of bias in the interpretation of case-control study results.
尽管病例对照研究中的选择偏倚已经得到了广泛研究，但对于不同种族群体中病例和对照的选择知之甚少。本研究比较了具有不同设计特征的病例对照研究中估计的儿童癌症发病率的种族差异。它还比较了病例对照研究报告的病例种族分布估计值与这些研究或相应地理区域和日历时期的基于人群的癌症登记处中完全确定病例的理想病例系列观察到的分布估计值。
回顾了北美发表于 1980 年至 2007 年的儿童白血病和脑肿瘤的同行评审出版物。种族/族裔的发病率数据由研究出版物、联邦癌症统计数据和癌症登记处汇编而成。进行荟萃分析以评估研究特征的种族/民族差异。比较了发表的病例对照研究中病例的种族分布与非偏置病例分布（即包括病例对照研究中参与和未参与的病例）或癌症登记处记录的病例。
在基于访谈的儿童癌症病例对照研究中，与病例相比，对照组中白人的比例往往高于非白人；然而，对于基于记录的病例对照研究，情况则相反。此外，与非参与病例或癌症登记处中的白人比例相比，发表的病例对照研究中参与病例的白人比例往往更高。
研究人员需要考虑不同种族群体的差异参与，这可能是解释病例对照研究结果时的一个潜在偏差来源。
