Bendayan Rebecca, Ramírez-Maestre Carmen, Ferrer Emilio, López Alicia, Esteve Rosa
Department of Psychobiology and Methodology of Behavioural Sciences, University of Malaga, Facultad de Psicologia, Campus de Teatinos s/n, Malaga 29071, Spain; MRC Unit for Lifelong Health and Ageing at UCL, 33 Bedford Place, London WC1B 5JU, United Kingdom.
Department of Personality, Assessment and Psychological Treatment, University of Malaga, Facultad de Psicologia, Campus de Teatinos s/n, Malaga 29071, Spain.
Scand J Pain. 2017 Jul;16:45-51. doi: 10.1016/j.sjpain.2017.02.009. Epub 2017 Mar 22.
BACKGROUND/AIMS: This longitudinal study investigated the pattern of change in pain intensity, disability, and depression in 232 chronic pain patients who were followed up for 2 years since pain onset. Most studies that have investigated changes in these variables over time have used participants who had already been in pain for more than 3 months. Few studies have followed up individuals from the acute phase onward and such studies used traditional statistical methods that cannot identify transition points over time or measure inter-individual variability.
We followed up individuals with chronic pain from pain onset up to 18 months and we examined their pain intensity, disability and depression trajectories using a modelling approach that allows to account for between and within-individual variability. We compared three patterns of change based on theoretical criterions: a simple linear growth model; a spline model with a 3-month transition point; and a spline model with a 6-month transition point. Time with pain was selected as time metric to characterise the change in these variables in the transition from acute to chronic pain. Sex and age differences were also examined.
The results showed that the pain intensity trajectory was best represented by the spline model with a 3-month transition point, whereas disability and depression were best explained by linear growth models. There were sex differences at intercept level in all the models. There were age differences at baseline for pain intensity. No sex or age differences were found for the slope.
Pain intensity decreased in the first 3 months but underwent no further change. Disability and depression slightly but constantly decreased over time. Although women and older individuals are more likely to report higher pain intensity or pain-related disability in the first three months with pain, no differences by sex or age appear to be associated with the changes in pain intensity, depression and disability through the process of chronification.
Our findings suggest that pain chronification could be considered a continuous process and contribute to the ongoing discussion on the utility of standard classifications of pain as acute or chronic from a clinical point of view. Clinical and intervention decisions based in these standard classifications should consider the differences in the trajectories of pain related variables over time. In addition, this article illustrates a statistical procedure that can be of utility to pain researchers.
背景/目的：这项纵向研究调查了232名慢性疼痛患者自疼痛发作起2年的疼痛强度、功能障碍和抑郁的变化模式。大多数研究这些变量随时间变化的研究使用的是已经疼痛超过3个月的参与者。很少有研究对从急性期开始的个体进行随访，并且此类研究使用的是传统统计方法，无法识别随时间的转变点或测量个体间差异。
我们对慢性疼痛个体从疼痛发作起随访至18个月，并使用一种能够考虑个体间和个体内差异的建模方法检查他们的疼痛强度、功能障碍和抑郁轨迹。我们根据理论标准比较了三种变化模式：简单线性增长模型；具有3个月转变点的样条模型；以及具有6个月转变点的样条模型。将疼痛时长选为时间指标，以描述从急性疼痛到慢性疼痛转变过程中这些变量的变化。还研究了性别和年龄差异。
结果表明，疼痛强度轨迹最适合用具有3个月转变点的样条模型表示，而功能障碍和抑郁最好用线性增长模型解释。在所有模型的截距水平存在性别差异。疼痛强度在基线时存在年龄差异。在斜率方面未发现性别或年龄差异。
疼痛强度在最初3个月下降，但之后没有进一步变化。功能障碍和抑郁随时间略有但持续下降。尽管女性和老年人在疼痛的前三个月更有可能报告更高的疼痛强度或与疼痛相关的功能障碍，但在慢性化过程中，疼痛强度、抑郁和功能障碍的变化似乎与性别或年龄无关。
我们的研究结果表明，疼痛慢性化可被视为一个连续过程，并有助于从临床角度对疼痛作为急性或慢性的标准分类的效用进行持续讨论。基于这些标准分类的临床和干预决策应考虑疼痛相关变量随时间轨迹的差异。此外，本文阐述了一种对疼痛研究人员有用的统计程序。
