Haas Mitchell, Aickin Mikel, Vavrek Darcy
Dean of Research, Center for Outcomes Studies, Western States Chiropractic College, Portland, OR 97230, USA.
J Manipulative Physiol Ther. 2010 Jan;33(1):5-13. doi: 10.1016/j.jmpt.2009.11.007.
The purpose of this article was to present a preliminary model to identify the effects of expectancy of treatment success and the patient-provider encounter (PPE) on outcomes in an open-label randomized trial.
Eighty participants with chronic cervicogenic headache (CGH) were randomized to 4 groups: 2 levels of treatment dose (8 or 16) and 2 levels of therapy from a chiropractor (spinal manipulation or light massage). Providers were instructed to have equal enthusiasm for all care. Structural equation modeling with standardized path coefficients (beta) was used in a path analysis to identify the effects of patient expectancy and the PPE on CGH pain. The model included monthly pain from baseline to 12 weeks. Expectancy and PPE were evaluated on Likert scales. The patient-provider encounter was measured as patient perception of chiropractor enthusiasm, confidence, and comfort with care.
Baseline patient expectancy was balanced across groups. The PPE measures were balanced across groups and consistent over the 8-week treatment period. Treatment and baseline pain had the strongest effects on pain outcomes (|beta| = .46-.59). Expectations had little effect on pain (abs value(beta) < .15). The patient-provider encounter had a weak effect on pain (abs value(beta)= .03-.27) and on subsequent confidence in treatment success (abs value(beta)= .09 and .12).
Encouraging equipoise in the PPE and balancing expectancy across treatment groups may protect against some confounding related to the absence of blinding in a randomized controlled trial of pain. In this trial, their effects were found to be small relative to the effects of treatment and baseline values.
本文旨在提出一个初步模型，以确定在开放标签随机试验中治疗成功预期和医患接触（PPE）对结果的影响。
80名慢性颈源性头痛（CGH）患者被随机分为4组：2个治疗剂量水平（8或16）和2种脊椎按摩师治疗水平（脊柱推拿或轻度按摩）。要求提供者对所有治疗具有同等的热情。在路径分析中使用具有标准化路径系数（β）的结构方程模型来确定患者预期和PPE对CGH疼痛的影响。该模型包括从基线到12周的每月疼痛情况。预期和PPE通过李克特量表进行评估。医患接触以患者对脊椎按摩师的热情、信心和护理舒适度的感知来衡量。
各治疗组间基线患者预期均衡。PPE测量在各治疗组间均衡，且在8周治疗期内保持一致。治疗和基线疼痛对疼痛结果的影响最强（|β| = 0.46 - 0.59）。预期对疼痛影响很小（绝对值（β）< 0.15）。医患接触对疼痛影响较弱（绝对值（β）= 0.03 - 0.27），对后续治疗成功信心的影响也较弱（绝对值（β）= 0.09和0.12）。
在PPE中鼓励均衡，并在各治疗组间平衡预期，可能有助于防止在疼痛随机对照试验中因缺乏盲法而产生的一些混杂因素。在本试验中，相对于治疗和基线值的影响，发现它们的影响较小。
