Nottingham Clinical Trials Unit, University of Nottingham, Nottingham, UK.
National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
Trials. 2022 Jun 27;23(1):535. doi: 10.1186/s13063-022-06481-9.
Blinding is an established approach in clinical trials which aims to minimise the risk of performance and detection bias. There is little empirical evidence to guide UK clinical trials units (CTUs) about the practice of blinding statisticians. Guidelines recommend that statisticians remain blinded to allocation prior to the final analysis. As these guidelines are not based on empirical evidence, this study undertook a qualitative investigation relating to when and how statisticians should be blinded in clinical trials.
Data were collected through online focus groups with various stakeholders who work in the delivery and oversight of clinical trials. Recordings of the focus groups were transcribed verbatim and thematic analysis was used to analyse the transcripts.
Thirty-seven participants from 19 CTUs participated in one of six focus groups. Four main themes were identified, namely statistical models of work, factors affecting the decision to blind statisticians, benefits of blinding/not blinding statisticians and practicalities. Factors influencing the decision to blind the statistician included available resources, study design and types of intervention and outcomes and analysis. Although blinding of the statistician is perceived as a desirable mitigation against bias, there was uncertainty about the extent to which an unblinded statistician might impart bias. Instead, in most cases, the insight that the statistician offers was deemed more important to delivery of a trial than the risk of bias they may introduce if unblinded. Blinding of statisticians was only considered achievable with the appropriate resource and staffing, which were not always available. In many cases, a standard approach to blinding was therefore considered unrealistic and impractical; hence the need for a proportionate risk assessment approach identifying possible mitigations.
There was wide variation in practice between UK CTUs regarding the blinding of trial statisticians. A risk assessment approach would enable CTUs to identify risks associated with unblinded statisticians conducting the final analysis and alternative mitigation strategies. The findings of this study will be used to design guidance and a tool to support this risk assessment process.
盲法是临床试验中一种既定的方法，旨在最大限度地降低操作和检测偏倚的风险。几乎没有经验证据可以指导英国临床试验单位（CTU）了解统计师盲法的实践。指南建议统计师在最终分析之前保持对分配的盲法。由于这些指南不是基于经验证据，因此本研究进行了一项定性调查，涉及统计师在临床试验中何时以及如何进行盲法。
通过与从事临床试验实施和监督的各种利益相关者进行在线焦点小组收集数据。焦点小组的录音被逐字转录，并使用主题分析对转录本进行分析。
来自 19 个 CTU 的 37 名参与者参加了六个焦点小组中的一个。确定了四个主要主题，即工作的统计模型、影响统计师盲法决策的因素、统计师盲法/不盲法的益处以及实际问题。影响统计师盲法决策的因素包括可用资源、研究设计以及干预和结局类型以及分析类型。尽管统计师盲法被认为是减轻偏倚的一种理想方法，但对于未盲法的统计师可能带来的偏见程度存在不确定性。相反，在大多数情况下，统计师提供的见解被认为比他们未盲法时可能引入的偏倚风险更重要。只有在适当的资源和人员配备的情况下才考虑对统计师进行盲法，而这些资源和人员配备并不总是可用的。在许多情况下，因此，标准的盲法方法被认为不切实际和不切实际；因此需要进行风险评估，确定可能的缓解措施。
英国 CTU 之间在试验统计师的盲法方面存在广泛的实践差异。风险评估方法将使 CTU 能够识别与未盲法统计师进行最终分析相关的风险以及替代缓解策略。本研究的结果将用于设计指南和工具来支持这一风险评估过程。
