Effectiveness of subgroup-specific pain rehabilitation: a randomized controlled trial in patients with chronic back pain

BACKGROUND: Prospective classification of patients with nonspecific chronic back pain into homogeneous subgroups might be an important objective in order to tailor interventions and improve treatment outcomes. AIM: This study investigated the effect of a subgroup-specific pain rehabilitation program based on the Multidimensional Pain Inventory (MPI ) Classification System compared to standard care. DESIGN: Single blinded, parallel group, pragmatic randomized controlled trial. SETTING: Inpatient subjects of a rehabilitation clinic. POPULATION: A total of 139 patients with chronic back pain. METHODS: Patients in both the experimental group and control group received during their 4-week in-house stay at the rehabilitation clinic on average four daily sessions of therapy. The patients in the experimental group received specific interventions, which were tailored to their subgroup classification profile. The patients in the control group participated in state-of-the-art care. The primary outcome was self-reported disability measured at 1, 3 and 12 months after randomization with the Oswestry Disability Index (ODI). Secondary outcomes were pain intensity, examiner-reported disability, anxiety and depression, catastrophizing, self-efficacy and global perceived effect. RESULTS: Groups were comparable under demographic and clinical characteristics. No significant differences between the experimental group and the control group for any of the outcomes and follow-up times were found in the intention-to-treat analysis. Compared to the 8-10 points considered as minimal clinically important difference for the ODI, effects within groups were small, e.g. the experimental group improved by 2.2 points at 1-month follow-up, 3.7 points at 3 months and 5.3 points at 12 months. CONCLUSIONS: This study failed to demonstrate that a subgroup-specific program was more effective than standard care. CLINICAL REHABILITATION IMPACT: Since the subgroup-specific interventions were equally effective as standard pain rehabilitation, subgroup classification and tailoring interventions may be an alternative in clinical care.