Autier Philippe
International Prevention Research Institute (IPRI), Lyon, 69002, France.
Clin Epidemiol. 2025 May 1;17:441-450. doi: 10.2147/CLEP.S515464. eCollection 2025.
Observational studies aimed at evaluating the effectiveness of screening mammography are prone to self-selection due to differences in personal characteristics between women attending and those not attending screening. A method based on a quantity has been promoted to correct for this bias, being the risk of breast cancer death in a group of women not attending screening compared to the risk of breast cancer death in a population without screening.
To estimate the amount of self-selection in observational studies aimed at evaluating screening mammography effectiveness and to estimate quantities needed to correct for this bias.
A first step quantified self-selection and quantities specific to Swedish randomized trials using the most recent publications. A second step estimated self-selection specific to cohort studies on screening mammography effectiveness using the relative risk of 0.54 for all-cause death from these studies and the relative risk of all-cause death of 0.98 reported in Swedish trials. Using self-selection estimated from cohort studies, the quantity needed to correct observational studies on screening mammography effectiveness was estimated. In a last step, corrections for self-selection in observational studies on screening mammography were retrieved.
The self-selection bias was 2.10 in Swedish trials. Self-selection in cohort studies was computed as (0.98/0.54) = 1.78. The quantity required to correct results of observational studies was 1.53. In 19 case-control and cohort studies on screening mammography effectiveness, the median quantity used for correction purposes was 1.16 (IQR: 1.11-1.28).
Compared to women attending screening, the risk of breast cancer death was approximately two times greater in women not attending screening. This increased risk was independent of screening effects. Most observational studies have overestimated the effectiveness of screening mammography because they used quantities that were too small to correct for self-selection.
旨在评估乳腺钼靶筛查有效性的观察性研究容易出现自我选择偏倚，这是由于参加筛查的女性与未参加筛查的女性在个人特征上存在差异。一种基于某个量的方法已被推广用于校正这种偏倚，该量是未参加筛查的一组女性的乳腺癌死亡风险与未进行筛查的总体人群的乳腺癌死亡风险之比。
估计旨在评估乳腺钼靶筛查有效性的观察性研究中的自我选择量，并估计校正这种偏倚所需的该量值。
第一步，利用最新出版物对瑞典随机试验特有的自我选择和该量值进行量化。第二步，利用这些研究中全因死亡的相对风险0.54以及瑞典试验中报告的全因死亡相对风险0.98，估计乳腺钼靶筛查有效性队列研究特有的自我选择。利用队列研究估计的自我选择，估计校正乳腺钼靶筛查有效性观察性研究所需的该量值。最后一步，获取乳腺钼靶筛查观察性研究中自我选择的校正值。
瑞典试验中的自我选择偏倚为2.10。队列研究中的自我选择计算为(0.98/0.54)=1.78。校正观察性研究结果所需的该量值为1.53。在19项关于乳腺钼靶筛查有效性的病例对照和队列研究中，用于校正目的的该量值中位数为1.16（四分位间距：1.11 - 1.28）。
与参加筛查的女性相比，未参加筛查的女性乳腺癌死亡风险大约高两倍。这种风险增加与筛查效果无关。大多数观察性研究高估了乳腺钼靶筛查的有效性，因为它们使用的该量值过小，无法校正自我选择偏倚。
