Understanding controlled trials - What is a patient preference trial?
Understanding controlled trials - What is a patient preference trial?
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DOI：
10.1136/bmj.316.7128.360
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发表时间：
1998-01-31
影响因子：
--
通讯作者：
Sibbald, B
中科院分区：
文献类型：
--
作者：
Torgerson, DJ;Sibbald, B
在随机对照试验中，当患者(或他们的临床医生)有如此强烈的治疗偏好而拒绝随机化时，一个常见的问题就会出现。1这些患者不参加试验可能会限制结果的推广，因为参与者可能没有代表性。当有强烈治疗偏好的患者被招募并随机分配时，存在另一个潜在的偏见来源。当不可能使患者对他们的治疗分配视而不见时，如果他们没有得到他们喜欢的治疗，他们可能会遭受怨恨的士气低落，而且他们可能会遵守得很差。另一方面，接受首选治疗的患者的依从性可能好于平均水平。因此，可能有一种治疗效果是由患者的偏好产生的，而不是由治疗效果产生的。到目前为止，怨恨的士气低落的影响是一个理论上的担忧，还没有在实践中得到证明，部分原因是它们很难评估。患者可根据偏好和愿意被随机分为三组：(A)没有强烈偏好因而同意随机化的患者；(B)仍同意随机化的有偏好的患者；(C)拒绝随机化并选择自己选择的治疗以应对患者偏好的患者，建议使用全面队列设计3或患者偏好试验。有治疗偏好的患者被允许接受他们想要的治疗；那些没有强烈观点的患者被按常规随机分配。因此，在A和B两种干预措施的试验中，我们最终得到了四组：随机到A组；首选A组；随机到B组；首选B组。这样的试验的分析是不确定的。任何使用非随机化组的比较都是不可靠的，因为存在未知和未控制的混杂因素。5因此，至少有一项分析应该是两个随机武器之间的比较。包括未随机分组的分析应被视为观察性研究，并在分析中调整已知的混杂因素。Olschewski和Scheurlen建议，使用随机化状态作为协变量的分析可能会有所帮助。3患者优先选择方法的另一个限制是它可能会增加试验的规模和成本。已经提出了一种部分随机化方法的替代方案，即在随机化之前得出患者偏好的强度和方向，所有同意的患者都被随机化。这种方法结合了部分随机化设计的优点--即收集偏好对结果影响的信息--但保留了完全随机化设计的严谨性。该设计已经用于背部疼痛的物理治疗的随机试验，尽管大多数患者表达了偏好，但没有患者拒绝随机分组。6在试验中确定和纳入患者偏好的实际优势尚未完全确立。然而，使用患者偏好设计，Henshaw等人在药物流产和手术流产的比较中，产生了关于不同偏好群体中两种治疗方法的可接受性的重要补充信息，这些信息在通常的试验中是无法获得的。7此外，最近的一项早期羊膜穿刺术与绒毛取样诊断胎儿畸形的首选试验表明，首选组与其随机等值组之间的妊娠失败率没有差异。8这项试验很重要，因为只有38%的患者接受了随机分组。因此，将未随机的患者包括在试验中提供了一些…
A common problem in randomised controlled trials arises when patients (or their clinicians) have such strong treatment preferences that they refuse randomisation. 1 The absence of these patients from trials may restrict generalisation of the results, as participants may not be representative. A further potential source of bias exists when patients with strong treatment preferences are recruited and randomised. When it is not possible to blind patients to their treatment allocation they may suffer resentful demoralisation2 if they do not receive their preferred treatment and may comply poorly. On the other hand, patients receiving their preferred treatment may comply better than average. There may therefore be a treatment effect which results from patient preferences and not from therapeutic efficacy. The effects of resentful demoralisation are so far a theoretical concern which have yet to be shown in practice, in part because they are difficult to evaluate. Patients may be placed in one of three groups according to preference and willingness to be randomised:(a) patients who have no strong preferences and therefore consent to randomisation;(b) patients with a preference who still consent to randomisation; and (c) patients who refuse randomisation and opt for their treatment of choice To cope with patient preferences the use of a comprehensive cohort design3 or the patient preference trial has been suggested. 4 Patients with treatment preferences are allowed their desired treatment; those who do not have strong views are randomised conventionally. Hence, in a trial of two interventions, A and B, we end up with four groups: randomised to A; prefer A; randomised to B; prefer B. The analysis of such a trial is uncertain. Any comparison using the nonrandomised groups is unreliable because of the presence of unknown and uncontrolled confounders. 5 At least one analysis should therefore be a comparison between the two randomised arms alone. Analyses which include the unrandomised groups should be treated as observational studies with known confounding factors adjusted for in the analysis. Olschewski and Scheurlen have suggested that an analysis using randomisation status as a covariate might be helpful. 3 A further limitation of the patient preference approach is that it may increase the size and cost of trials. An alternative to the partially randomised approach has been proposed whereby the strength and direction of patient preferences are elicited before randomisation, with all consenting patients randomised. 6 This approach combines the advantage of the partially randomised design—that is, gathering information on the effect of preference on outcome—but retains the rigour of a full randomised design. 6 The design has been used in a randomised trial of physiotherapy treatment for back pain and, despite most patients expressing a preference, no patient refused randomisation. 6 The practical advantages of establishing and including patient preferences in trials has not been fully established. However, using a patient preference design, Henshaw et al in a comparison of medical versus surgical abortion produced important additional information on the acceptability of the two treatments in different preference groups which would not have been be available in the usual trial. 7 In addition, a recent preference trial of early amniocentesis versus chorionic villus sampling for diagnosing fetal abnormalities showed that rate of pregnancy loss did not differ between the preference group and their randomised equivalent. 8 This trial is important in that only 38% of patients accepted randomisation. Thus, including the unrandomised patients in the trial offered some …