Evaluating the integration of the reported treatment mechanisms and goal of treatment in randomized controlled trials for low back pain: protocol for a meta-epidemiological analysis.

OBJECTIVES: Treatment mechanisms for exercise, cognitive behavioral therapy (CBT) and spinal manipulative therapy (SMT) are broadly theorized and examined in basic science studies; however, they are not typically incorporated in the design of randomized controlled trials (RCTs) for low back pain (LBP). The overall aim of this study is to answer the question, "what is the role of mechanisms and goal of treatment in RCTs for LBP?" Specifically, the objective is to answer: (1) how many RCTs of LBP consider an intervention-specific mechanism?, (2) are these mechanisms incorporated in their study design (ie, inclusion criteria)?; (3) Is an outcome measure aligned to the proposed mechanism measured at follow-up?; and, (4) do RCTs which describe a mechanism for the intervention, and include this in the design (ie, the inclusion criteria and outcome measures) of the study, demonstrate a different/stronger intervention effect compared to those that do not? The same line of questioning applies to goal of treatment.

STUDY DESIGN AND SETTING: The basis for our analyses will be formed by the RCTs included in the Cochrane reviews investigating the effects of exercise, CBT, and SMT for chronic LBP. We will report the proportion of RCTs that: (1) describe a mechanism for the intervention; (2) incorporate the mechanism in the inclusion criteria; and (3) report an outcome measure aligned to the proposed mechanism. Similar proportions will be reported for goal of treatment. The data will be summarized for all trials, and stratified by intervention type. Also, we will examine the association between difference in pain or functional status at 3-month follow-up and the central determinant (mechanism (yes/no) for the intervention group (SMT, exercise, and CBT)) by performing metaregression analyses. The same analyses will be run for goal of treatment.

CONCLUSION: This metaepidemiological analysis will provide insight into the proportion of RCTs that report a mechanism/goal of treatment for the intervention as well as outlining the differences in treatment outcomes for RCTs that do report an intervention specific mechanism or goal vs. those that do not. This may help improve RCT quality by highlighting the importance of including participants with criteria relevant to the treatment and/or mechanism under investigation.

PLAIN LANGUAGE SUMMARY: This study looks at whether and how clinical trials explain how a treatment works (this is called a mechanism), if they test those treatments on the right group of people and if they are using the right tools to measure if the treatment actually works. At the moment, it is not clear whether explaining how a treatment works makes a difference in how well a treatment works compared to other treatments. Understanding both how a treatment works and who it works best for, helps with making a better treatment choice. For example, imagine a trial that tests exercises to strengthen the abdominal muscles for people with low back pain (LBP). If the trail includes people who already have strong abdominal muscles, the results may not show the true benefit of the exercises. It would make more sense to include people with weak abdominal muscles, as they are the ones most likely to benefit from the exercises. Also, you would need the right tool to assess whether a treatment actually works. Going back to the previous example, you have to use a tool that can accurately measure abdominal muscle strength to tell if the abdominal muscles become stronger. In our study, we will look at how many studies explain how a treatment works (in other words, explain the treatment mechanism), and whether they use that information to decide which people to include and to choose the right tool to the measure the results. In simple terms, are trials being done with the right group of people, and are the effects measured with the right tool? To answer this, we will evaluate trials that are included in the Cochrane reviews for three common treatments for chronic LBP; exercise, cognitive behavioral therapy (CBT), and spinal manipulative therapy (SMT).