Department of Social Dentistry and Behavioural Sciences, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands.
Caries Res. 2011;45(3):269-74. doi: 10.1159/000325742. Epub 2011 May 12.
Studies reporting clinical and non-clinical parameters of participants and non-participants of clinical trials are scarce. In the available studies non-participants were likely to show less favourable outcomes than participants on both socioeconomic parameters as well as on caries experience. However, the impact of non-participation on the total sample of the research population is not established. In the present study, as part of baseline data collection for a randomized controlled trial on caries-preventive strategies, 346 parents of children 6.0 years (± 3 months) of age were approached to let their child participate. Sixty parents refused, but 56 of them were willing to fill out the same set of questionnaires and to allow their child to be clinically examined once. Parents from participating children had higher socioeconomic status, were more often of autochthonous origin and scored better on knowledge questions than parents of non-participating children. Furthermore, parents of participating children reported a higher willingness to invest, were more likely to hold on to regular meals and their child had lower levels of plaque compared to non-participating children. Surprisingly, the participating children had higher dmfs scores than the non-participating children. Their care index (fs/ds + fs) was higher than that of non-participating children. Based on the findings of this study, the presumption that non-participating children will show less favourable clinical outcomes cannot be supported. Although participants differed from non-participants, they did not differ from the total population. It is suggested that the external validity of a randomized controlled trial on caries-preventive strategies is not necessarily affected by non-participation bias.
报告临床试验的参与者和非参与者的临床和非临床参数的研究很少。在现有的研究中，非参与者在社会经济参数以及龋齿经历方面，都比参与者更有可能出现不利的结果。然而，非参与对研究人群的总样本的影响尚未确定。在本研究中，作为龋齿预防策略的随机对照试验的基线数据收集的一部分，346 名 6.0 岁（±3 个月）儿童的家长被邀请让他们的孩子参与。60 名家长拒绝了，但其中 56 名愿意填写相同的问卷，并允许他们的孩子接受一次临床检查。参与儿童的家长社会经济地位较高，更多是土生土长的，在知识问题上的得分也高于非参与儿童的家长。此外，参与儿童的家长表示更愿意投资，更有可能坚持定期用餐，他们的孩子的牙菌斑水平也低于非参与儿童。令人惊讶的是，参与儿童的 dmfs 得分高于非参与儿童。他们的保健指数（fs/ds+fs）高于非参与儿童。基于这项研究的结果，不能支持非参与儿童的临床结果不太有利的假设。尽管参与者与非参与者不同，但他们与总人群没有不同。有人建议，龋齿预防策略的随机对照试验的外部有效性不一定受到非参与偏差的影响。
