Department of Surgery and Perioperative Care, Dell Medical School, The University of Texas at Austin, Austin, TX, USA.
Clin Orthop Relat Res. 2018 Nov;476(11):2219-2228. doi: 10.1097/CORR.0000000000000425.
Studies on how psychologic factors influence the placebo effect have shown conflicting results in an experimental setting. Pessimists are more likely to experience a nocebo effect (feel worse after an inert intervention), whereas other studies suggest that patients with more symptoms of depression or anxiety or greater neuroticism have a greater response to a placebo. This is important because treatment benefits are potentiated by placebo effects, and optimal utilization of this phenomenon may improve clinical outcomes.
QUESTIONS/PURPOSES: (1) What psychologic factors are associated with a decrease in magnitude of limitations (Disabilities of the Arm, Shoulder and Hand [DASH] score) and pain intensity (visual analog scale [VAS] for pain) after placebo injections for the treatment of painful nontraumatic upper extremity conditions? (2) What psychologic factors are associated with achieving a minimum clinically important difference (MCID) in disability and pain intensity?
We performed a secondary analysis of data acquired in two prospective, double-blind, randomized controlled trials of patients with lateral elbow pain, trapeziometacarpal arthrosis, and de Quervain tendinopathy who received a single injection of dexamethasone and lidocaine or lidocaine alone (placebo). One hundred six patients were included between June 2003 and February 2008. Sixty-three patients (59%) received dexamethasone and lidocaine, and we analyzed the subset of 43 patients (41%) who received lidocaine alone. The primary outcomes of interest were the DASH questionnaire and the VAS for pain measured three times: when they received the injection, between 1 and 3 months after the injection, and between 5 and 8 months after the injection. Seven patients missed the first followup visit and 14 patients missed the second visit. Based on previous research, we chose a MCID threshold of 10 for the DASH and a threshold of 1.0 for the VAS score. In bivariate analysis, we accounted for sex, race, marital status, degree, education, work status, pretreatment pain, diagnosis, symptoms of depression (Center of Epidemiologic Studies-Depression Scale), coping strategies in response to nociception (Pain Catastrophizing Scale), and personality traits (measured with the Multidimensional Health Locus of Control scale and the Eysenck Personality Questionnaire-Revised score). Variables with p values < 0.10 in bivariate analysis were included in the multivariable regression models. An a priori power analysis showed that a sample of 43 participants provides 80% statistical power, with α set at 0.05, for a regression with five predictors if the depression score would account for 15% or more of the variability in pain score. We used multiple imputations (imputations = 50) for a total of 66 (8.5%) missing or incomplete questionnaires.
In the final multivariable models, no psychologic factors were associated with a change in DASH score between injection and followup, and no factors were associated with greater decrease in pain intensity. After injection, no psychologic factors were independently associated with achieving a MCID in the DASH and VAS.
Our study confirms that patient factors are less important mediators of the placebo effect than clinician factors. In other words, clinician warmth and competence can help diminish symptoms and limitations of people in various states of mind, even when using inert or ineffective treatments.
Level II, therapeutic study.
在实验环境中，有关心理因素如何影响安慰剂效应的研究结果相互矛盾。悲观主义者更有可能经历反安慰剂效应（在接受无效干预后感觉更糟），而其他研究表明，抑郁或焦虑症状更多或神经质程度更高的患者对安慰剂的反应更大。这很重要，因为安慰剂效应可以增强治疗效果，而最佳利用这种现象可能会改善临床结果。
问题/目的：（1）在接受用于治疗疼痛性非创伤性上肢疾病的安慰剂注射后，哪些心理因素与手臂、肩部和手部残疾（DASH 评分）和疼痛强度（疼痛视觉模拟量表 [VAS]）的减轻幅度有关？（2）哪些心理因素与达到残疾和疼痛强度的最小临床重要差异（MCID）有关？
我们对 2003 年 6 月至 2008 年 2 月期间接受外侧肘部疼痛、腕掌关节炎和桡侧伸肌腱炎患者单次接受地塞米松和利多卡因或利多卡因（安慰剂）注射的两项前瞻性、双盲、随机对照试验的数据进行了二次分析。共纳入 106 例患者。63 例（59%）患者接受地塞米松和利多卡因治疗，我们分析了 43 例（41%）仅接受利多卡因治疗的患者亚组。主要观察指标为 DASH 问卷和 VAS 疼痛评分，分别在 3 次测量时进行测量：注射时、注射后 1-3 个月和注射后 5-8 个月。7 例患者错过了第一次随访，14 例患者错过了第二次随访。根据先前的研究，我们选择了 DASH 的 MCID 阈值为 10，VAS 评分的阈值为 1.0。在双变量分析中，我们考虑了性别、种族、婚姻状况、程度、教育、工作状况、治疗前疼痛、诊断、抑郁症状（流行病学研究中心抑郁量表）、对伤害性刺激的应对策略（疼痛灾难化量表）和人格特质（通过多维健康控制源量表和艾森克人格问卷修订版分数测量）。在双变量分析中 p 值 < 0.10 的变量被纳入多变量回归模型。预先的功效分析表明，对于有 5 个预测因子的回归分析，如果抑郁评分占疼痛评分变化的 15%或更多，那么样本量为 43 名参与者的研究提供了 80%的统计功效，α 设置为 0.05。我们使用了 50 次多重插补（插补= 50），以处理 66 份（8.5%）缺失或不完整的问卷。
在最终的多变量模型中，没有心理因素与注射和随访之间的 DASH 评分变化有关，也没有因素与疼痛强度的更大降低有关。注射后，没有心理因素与 DASH 和 VAS 中的 MCID 独立相关。
我们的研究证实，与临床医生因素相比，患者因素是安慰剂效应的次要调节因素。换句话说，即使使用无效或无效的治疗方法，临床医生的热情和能力也可以帮助减轻处于不同心态的人的症状和限制。
II 级，治疗研究。
