Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, INF 581, D-69120 Heidelberg, Germany.
J Clin Epidemiol. 2013 Feb;66(2):202-8. doi: 10.1016/j.jclinepi.2012.09.008.
In the evaluation of cancer screening tests, cancer-free controls are often matched to cancer cases on factors such as sex and age. We assessed the potential merits and pitfalls of such matching using an example from colorectal cancer (CRC) screening.
We compared sex and age distribution of CRC cases and cancer-free people undergoing screening colonoscopy in Germany in 2006 and 2007. We assessed specificity by sex and age of two immunochemical fecal occult blood tests (iFOBTs) in a study among screening colonoscopy participants conducted in the same years, and we assessed the expected impact of matching by sex and age on the validity of specificity estimates at various cut points.
In the screening colonoscopy program, the proportion of men and mean age were 59.6% and 68.6 years among 10,324 CRC patients compared with 45.6% and 64.7 years, respectively, among 997,490 cancer-free participants. The specificity of the iFOBTs was higher among women than among men and decreased with age. Matching of cancer-free controls by age and sex would have led to the underestimation of specificity at all cut points assessed.
In the evaluation of cancer screening tests, matching of controls may lead to biased estimates of specificity.
在癌症筛查试验的评估中，通常会根据性别和年龄等因素将无癌症对照与癌症病例相匹配。我们使用结直肠癌（CRC）筛查的一个实例来评估这种匹配的潜在优点和缺陷。
我们比较了 2006 年和 2007 年在德国接受筛查结肠镜检查的 CRC 病例和无癌症人群的性别和年龄分布。我们评估了两项免疫化学粪便潜血试验（iFOBT）在同年进行的筛查结肠镜检查参与者研究中的性别和年龄特异性，并评估了性别和年龄匹配对不同切点特异性估计值的有效性的预期影响。
在筛查结肠镜检查计划中，在 10324 例 CRC 患者中，男性的比例和平均年龄分别为 59.6%和 68.6 岁，而在 997490 例无癌症参与者中，男性的比例和平均年龄分别为 45.6%和 64.7 岁。iFOBT 的特异性在女性中高于男性，并且随着年龄的增长而降低。通过年龄和性别匹配无癌症对照会导致在评估的所有切点特异性估计值偏低。
在癌症筛查试验的评估中，对照的匹配可能会导致特异性的估计值出现偏差。
