The Nordic Maintenance Care Program: Does psychological profile modify the treatment effect of a preventive manual therapy intervention? A secondary analysis of a pragmatic randomized controlled trial

Background
Chiropractic maintenance care is effective as secondary/tertiary prevention of non-specific low back pain (LBP), but the potential effect moderation by psychological characteristics is unknown. The objective was to investigate whether patients in specific psychological sub-groups had different responses to MC with regard to the total number of days with bothersome pain and the number of treatments.
Method
Data from a two-arm randomized pragmatic multicenter trial with a 12-month follow up, designed to investigate the effectiveness of maintenance care, was used. Consecutive patients, 18–65 years of age, with recurrent and persistent LBP seeking chiropractic care with a good effect of the initial treatment were included. Eligible subjects were randomized to either maintenance care (prescheduled care) or to the control intervention, symptom-guided care. The primary outcome of the trial was the total number of days with bothersome LBP collected weekly for 12 months using an automated SMS system. Data used to classify patients according to psychological subgroups defined by the West Haven-Yale Multidimensional Pain Inventory (adaptive copers, interpersonally distressed and dysfunctional) were collected at the screening visit.
Results
A total of 252 subjects were analyzed using a generalized estimating equations linear regression framework. Patients in the dysfunctional subgroup who received maintenance care reported fewer days with pain (-30.0; 95% CI: -36.6, -23.4) and equal number of treatments compared to the control intervention. In the adaptive coper subgroup, patients who received maintenance care reported more days with pain (10.7; 95% CI: 4.0, 17.5) and more treatments (3.9; 95% CI: 3.5, 4.2). Patients in the interpersonally distressed subgroup reported equal number of days with pain (-0.3; 95% CI: -8.7, 8.1) and more treatments (1.5; 95% CI: 0.9, 2.1) on maintenance care.
Conclusions
Psychological and behavioral characteristics modify the effect of MC and should be considered when recommending long-term preventive management of patients with recurrent and persistent LBP.

背景
脊椎按摩维持治疗（chiropractic maintenance care）可作为非特异性下腰痛（non-specific low back pain, LBP）的二级/三级预防手段，但其疗效是否受心理特征的调节作用目前尚不明确。本研究旨在探讨不同心理亚组患者对维持治疗的响应是否存在差异，评估指标包括困扰性疼痛总天数与治疗次数。

方法
本研究使用一项针对维持治疗疗效开展的双臂随机实用型多中心试验数据，该试验随访周期为12个月。研究纳入年龄18~65岁、复发性持续性非特异性下腰痛且初始脊椎按摩治疗效果良好的连续就诊患者。符合入组标准的受试者被随机分配至维持治疗组（预设治疗）或对照组（症状引导治疗）。本试验的主要结局指标为：通过自动化短信系统每周收集12个月内的困扰性下腰痛总天数。研究在筛查访视时收集了用于基于西黑文-耶鲁多维疼痛量表（West Haven-Yale Multidimensional Pain Inventory）划分心理亚组的数据，该量表将患者分为适应性应对者、人际困扰型与功能障碍型三类。

结果
本研究共纳入252名受试者，采用广义估计方程（generalized estimating equations）线性回归框架进行分析。与对照组相比，功能障碍型亚组中接受维持治疗的患者报告的疼痛天数更少（-30.0；95%置信区间：-36.6，-23.4），且治疗次数无显著差异。适应性应对者亚组中，接受维持治疗的患者报告的疼痛天数更多（10.7；95%置信区间：4.0，17.5），治疗次数也更多（3.9；95%置信区间：3.5，4.2）。人际困扰型亚组患者接受维持治疗后，疼痛天数无显著变化（-0.3；95%置信区间：-8.7，8.1），但治疗次数有所增加（1.5；95%置信区间：0.9，2.1）。

结论
心理与行为特征可调节维持治疗的疗效，因此在为复发性持续性非特异性下腰痛患者推荐长期预防性管理方案时，应将患者的心理亚组特征纳入考量。