McCarney Rob, Warner James, Iliffe Steve, van Haselen Robbert, Griffin Mark, Fisher Peter
Department of Psychological Medicine, Imperial College London, UK.
BMC Med Res Methodol. 2007 Jul 3;7:30. doi: 10.1186/1471-2288-7-30.
The 'Hawthorne Effect' may be an important factor affecting the generalisability of clinical research to routine practice, but has been little studied. Hawthorne Effects have been reported in previous clinical trials in dementia but to our knowledge, no attempt has been made to quantify them. Our aim was to compare minimal follow-up to intensive follow-up in participants in a placebo controlled trial of Ginkgo biloba for treating mild-moderate dementia.
Participants in a dementia trial were randomised to intensive follow-up (with comprehensive assessment visits at baseline and two, four and six months post randomisation) or minimal follow-up (with an abbreviated assessment at baseline and a full assessment at six months). Our primary outcomes were cognitive functioning (ADAS-Cog) and participant and carer-rated quality of life (QOL-AD).
We recruited 176 participants, mainly through general practices. The main analysis was based on Intention to treat (ITT), with available data. In the ANCOVA model with baseline score as a co-variate, follow-up group had a significant effect on outcome at six months on the ADAS-Cog score (n = 140; mean difference = -2.018; 95%CI -3.914, -0.121; p = 0.037 favouring the intensive follow-up group), and on participant-rated quality of life score (n = 142; mean difference = -1.382; 95%CI -2.642, -0.122; p = 0.032 favouring minimal follow-up group). There was no significant difference on carer quality of life.
We found that more intensive follow-up of individuals in a placebo-controlled clinical trial of Ginkgo biloba for treating mild-moderate dementia resulted in a better outcome than minimal follow-up, as measured by their cognitive functioning.
Current controlled trials: ISRCTN45577048.
“霍桑效应”可能是影响临床研究结果推广至常规医疗实践的一个重要因素，但相关研究较少。此前在痴呆症临床试验中曾报道过霍桑效应，但据我们所知，尚未有人尝试对其进行量化。我们的目的是在一项银杏叶治疗轻中度痴呆症的安慰剂对照试验中，比较参与者接受最小随访与强化随访的效果。
痴呆症试验的参与者被随机分为强化随访组（在基线、随机分组后2个月、4个月和6个月进行全面评估访视）或最小随访组（在基线进行简短评估，在6个月进行全面评估）。我们的主要结局指标是认知功能（ADAS-Cog）以及参与者和照料者评定的生活质量（QOL-AD）。
我们主要通过全科医疗招募了176名参与者。主要分析基于意向性分析（ITT），采用可用数据。在以基线分数作为协变量的协方差分析模型中，随访组对6个月时的ADAS-Cog评分结局有显著影响（n = 140；平均差值 = -2.018；95%置信区间 -3.914，-0.121；p = 0.037，强化随访组更优），对参与者评定的生活质量评分也有显著影响（n = 142；平均差值 = -1.382；95%置信区间 -2.642，-0.122；p = 0.032，最小随访组更优）。照料者的生活质量方面无显著差异。
我们发现，在一项银杏叶治疗轻中度痴呆症的安慰剂对照临床试验中，对个体进行更强化的随访在认知功能方面比最小随访能带来更好的结局。
当前对照试验：ISRCTN45577048。
