Friedman D R, Dubin N
National Cancer Institute, Radiation Epidemiology Branch, Bethesda, MD.
Am J Epidemiol. 1991 May 15;133(10):974-84. doi: 10.1093/oxfordjournals.aje.a115817.
The feasibility and validity of using case-control methods to evaluate the efficacy of breast cancer screening were investigated using data from the Health Insurance Plan of Greater New York Breast Cancer Screening Trial. Women who died of breast cancer were compared with individually matched controls of the same age who had equal or greater survival times. To minimize the effects of self-selection bias, most analyses focused on the 95 cases and 380 matched controls who had been screened at least once and for whom covariate data were available. A statistically significant effect for being screened more than once versus being screened once, uncorrected for healthy-screenee bias, was found (odds ratio = 0.13, p less than 0.001). After correction for healthy-screenee bias, the effect was not statistically significant (odds ratio = 0.54, p = 0.15). Possible explanations for this statistical nonsignificance are: 1) correction for healthy-screenee bias entails loss of power and 2) the correction procedure used may, under some circumstances, result in bias toward the null hypothesis. Further research into means of eliminating healthy-screenee bias is needed to improve the applicability of case-control methods to the evaluation of screening efficacy.
利用纽约大都会健康保险计划乳腺癌筛查试验的数据，研究了采用病例对照法评估乳腺癌筛查效果的可行性和有效性。将死于乳腺癌的女性与年龄相同、生存时间相等或更长的个体匹配对照进行比较。为尽量减少自我选择偏倚的影响，大多数分析集中在至少接受过一次筛查且有协变量数据的95例病例和380例匹配对照上。在未校正健康筛查者偏倚的情况下，发现多次筛查与单次筛查相比有统计学显著效果（优势比=0.13，p<0.001）。校正健康筛查者偏倚后，该效果无统计学显著性（优势比=0.54，p=0.15）。这种统计学无显著性的可能解释为：1）校正健康筛查者偏倚会导致检验效能降低；2）所采用的校正程序在某些情况下可能导致向零假设的偏倚。需要进一步研究消除健康筛查者偏倚的方法，以提高病例对照法在评估筛查效果方面的适用性。
