Department of General Practice, University of Copenhagen, Øster Farimagsgade 5, 24Q, 1014 Copenhagen, Denmark.
Lung Cancer. 2011 Sep;73(3):325-31. doi: 10.1016/j.lungcan.2010.12.018. Epub 2011 Feb 15.
Participation bias might affect the results and the representability of randomised controlled trials. We investigated the degree of socio-demographic and psychosocial participation bias in the Danish Lung Cancer Screening Trial (DLCST).
In DLCST the questionnaire COS-LC (Consequences of Screening in Lung Cancer) was used to measure the psychosocial aspects of screening. To investigate a difference with a comparable representative sample from the Danish population, we sent out an inclusion questionnaire to 3999 Danes in the age from 50 to 70 years randomly selected from the Central National Register. Those who completed the inclusion questionnaire and met the inclusion criteria from DLCST received the COS-LC. Those who completed the COS-LC-and thus formed a population sample comparable to DLCST - were compared to the DLCST participants on socio-demographics and psychosocial measures.
Participation rates were high among the comparable population sample: 75.3% completed the inclusion questionnaire and 77.4% of those who were eligible completed the COS-LC. The analyses revealed differences between the DLCST participants and the comparable population sample in the following socio-demographic aspects: social group, living alone, gender, age and geographical area. DLCST participants reported less negative psychosocial aspects than the comparable population sample.
The present study has shown substantial socio-demographic and psychosocial participation bias in DLCST.
参与偏差可能会影响随机对照试验的结果和代表性。我们研究了丹麦肺癌筛查试验（DLCST）中社会人口学和心理社会参与偏差的程度。
在 DLCST 中，使用问卷 COS-LC（肺癌筛查的后果）来测量筛查的心理社会方面。为了调查与丹麦人群中具有可比性的代表性样本之间的差异，我们从中央国家登记处随机选择了 50 至 70 岁的 3999 名丹麦人发送了一份纳入问卷。那些完成了纳入问卷并符合 DLCST 纳入标准的人收到了 COS-LC。那些完成了 COS-LC 并因此形成了与 DLCST 可比的人群样本的人，与 DLCST 参与者在社会人口统计学和心理社会措施方面进行了比较。
可比人群样本的参与率很高：75.3%完成了纳入问卷，77.4%符合条件的人完成了 COS-LC。分析显示，DLCST 参与者与可比人群样本在以下社会人口学方面存在差异：社会群体、独居、性别、年龄和地理区域。DLCST 参与者报告的负面心理社会方面比可比人群样本少。
本研究表明 DLCST 中存在大量社会人口学和心理社会参与偏差。
