Melis René J F, Teerenstra S, Rikkert M G M Olde, Borm G F
Department of Geriatric Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
J Clin Epidemiol. 2008 Nov;61(11):1169-75. doi: 10.1016/j.jclinepi.2007.12.001. Epub 2008 Jun 11.
In the Dutch EASYcare Study, pseudo cluster randomization (PCR) randomized clinicians in two groups (H and L) with a high or a low proportion of the patients of the clinician randomized to intervention or to control arm accordingly. We used PCR because cluster randomization risked selection bias and individual randomization risked contamination. We evaluated the performance of PCR.
Clinicians were asked about treatment arm preferences, recruitment behavior, possible contaminating behavior, and what they thought the allocation ratio was. We compared patients' baseline characteristics and clinicians' recruitment rates.
The groups were comparable at baseline. Clinicians favored the intervention arm (Visual Analogue Scale 14.5 [SD 15.6]; 0-100; 0=strongly favoring intervention arm, 100=strongly favoring usual care arm) and 58% said they would have recruited fewer patients had every participant been allocated to the control group. Sixty five percent of clinicians used intervention elements in control patients. Sixty seven percent of clinicians estimated that a 50:50 allocation ratio was used.
The assumptions underlying PCR largely applied in this study. PCR performed satisfactorily without signs of unblinding or selection bias.
在荷兰的EASYcare研究中，伪整群随机化（PCR）将临床医生分为两组（H组和L组），根据临床医生所负责患者被随机分配到干预组或对照组的比例高低进行分组。我们采用PCR是因为整群随机化存在选择偏倚风险，而个体随机化存在污染风险。我们评估了PCR的效果。
询问临床医生对治疗组的偏好、招募行为、可能的污染行为以及他们认为的分配比例。我们比较了患者的基线特征和临床医生的招募率。
两组在基线时具有可比性。临床医生更倾向于干预组（视觉模拟量表评分为14.5[标准差15.6]；范围0 - 100；0表示强烈倾向于干预组，100表示强烈倾向于常规治疗组），58%的临床医生表示，如果每个参与者都被分配到对照组，他们会招募更少的患者。65%的临床医生在对照组患者中使用了干预措施。67%的临床医生估计分配比例为50:50。
PCR的基本假设在本研究中大多适用。PCR表现令人满意，没有揭盲或选择偏倚的迹象。
