Dose or content? Effectiveness of pain rehabilitation programs for patients with chronic low back pain: a systematic review

We sought to systematically analyze the influence of dose of pain rehabilitation programs (PRPs) for patients with chronic low back pain (CLBP) on disability, work participation, and quality of life (QoL). Literature searches were performed in PubMed, Cochrane Library, Cinahl, and Embase up to October 2012, using MeSH terms, other relevant terms and free-text words. Randomized controlled trials in English, Dutch, and German, analyzing the effect of PRPs, were included. One of the analyzed interventions had to be a PRP. Outcomes should be reported regarding disability, work participation, or QoL. To analyze dose, the number of contact hours should be reported. Two reviewers independently selected titles, abstracts, and full-text articles on the basis of inclusion and exclusion criteria. Data were extracted and risk of bias was assessed. Effect sizes (ES) were calculated for each intervention, and influence of dose variables was analyzed by a mixed model analysis. Eighteen studies were identified, reporting a wide variety of dose variables and contents of PRPs. Analyses showed that evaluation moment, number of disciplines, type of intervention, duration of intervention in weeks, percentage of women, and age influenced the outcomes of PRPs. The independent effect of dose variables could not be distinguished from content because these variables were strongly associated. Because dose variables were never studied separately or reported independently, we were not able to disentangle the relationship between dose, content, and effects of PRPs on disability, work participation, and QoL.