Sean Monica, Coulombe-Lévêque Alexia, Nadeau William, Charest Anne-Catherine, Martel Marylie, Léonard Guillaume, Tétreault Pascal
Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada.
Department of Anesthesiology, Sherbrooke, QC, Canada.
Pain Rep. 2024 Apr 26;9(3):e1157. doi: 10.1097/PR9.0000000000001157. eCollection 2024 Jun.
Isolating the effect of an intervention from the natural course and fluctuations of a condition is a challenge in any clinical trial, particularly in the field of pain. Regression to the mean (RTM) may explain some of these observed fluctuations.
In this paper, we describe and quantify the natural trajectory of questionnaire scores over time, based on initial scores.
Twenty-seven untreated chronic low back pain patients and 25 healthy controls took part in this observational study, wherein they were asked to complete an array of questionnaires commonly used in pain studies during each of 3 visits (V1, V2, V3) at the 2-month interval. Scores at V1 were classified into 3 subgroups (extremely high, normal, and extremely low), based on z-scores. The average delta (∆ = V2 - V1) was calculated for each subgroup, for each questionnaire, to describe the evolution of scores over time based on initial scores. This analysis was repeated with the data for V2 and V3.
Our results show that high initial scores were widely followed by more average scores, while low initial scores tended to be followed by similar (low) scores.
These trajectories cannot be attributable to RTM alone because of their asymmetry, nor to the placebo effect as they occurred in the absence of any intervention. However, they could be the result of an Effect of Care, wherein participants had meaningful improvements simply from taking part in a study. The improvement observed in patients with high initial scores should be carefully taken into account when interpreting results from clinical trials.
在任何临床试验中，将干预措施的效果与病情的自然发展过程及波动隔离开来都是一项挑战，在疼痛领域尤其如此。均值回归（RTM）可能解释了其中一些观察到的波动情况。
在本文中，我们根据初始分数描述并量化问卷分数随时间的自然轨迹。
27名未经治疗的慢性下腰痛患者和25名健康对照参与了这项观察性研究，要求他们在3次就诊（V1、V2、V3）中的每次就诊时，每隔2个月完成一系列疼痛研究中常用的问卷。根据z分数，将V1时的分数分为3个亚组（极高、正常和极低）。针对每个亚组、每份问卷计算平均差值（∆ = V2 - V1），以根据初始分数描述分数随时间的变化情况。对V2和V3的数据重复进行此分析。
我们的结果表明，初始分数高之后往往是更接近平均水平的分数，而初始分数低之后往往是类似的（低）分数。
这些轨迹不能仅归因于均值回归，因为它们具有不对称性，也不能归因于安慰剂效应，因为它们是在没有任何干预的情况下出现的。然而，它们可能是护理效应的结果，即参与者仅仅通过参与研究就有了有意义的改善。在解释临床试验结果时，应仔细考虑初始分数高的患者中观察到的改善情况。
