There is wide international consensus on the need of having agreed and standardised sets of outcomes, better known as ‘core outcome sets’ (COSs). A COS represents the minimum that should be measured and reported in all clinical trials for a specific health condition, and that can also be suitable for use in other types of studies or clinical practice. The outcomes included in a COS do not have necessarily to be primary outcomes in a trial but they can be measured alongside trial-specific outcomes. In fact, the use of outcomes included in a COS is important as it facilitates evidence synthesis, by increasing statistical power of meta-analysis and improving reliability of systematic reviews.
A standardized set of outcomes for low back (LBP) clinical research was developed in the late nineties by a group of experts at the second International Forum for Primary Care Research in LBP. In more recent years, international initiatives like OMERACT and COMET have fostered and redefined methodological research in this area. These recent developments persuaded a group of experienced researchers (renamed as International Steering Committee) on the need of updating the existing standardized set for LBP, by developing a COS. The Steering Committee defined the scope of this COS (i.e. measurement of efficacy or effectiveness of interventions for non-specific LBP), established the methodology of the study and decided that the first step of this update was to determine which outcome domains should be measured and reported in all clinical trials for non-specific LBP.The recently developed OMERACT framework was used to structure a list of 41 potential core outcome domains. This list was presented in a three-round Delphi survey to a large panel of experts, including researchers and care providers from various disciplines, and patients. All panellists were asked to vote on the importance, overlap and/or addition of the potential core domains, and to provide the reasoning for their answers. In the last Delphi round overall consensus (at least 67% of the panel) was reached on the inclusion of three outcome domains in the COS: ‘physical functioning’, ‘pain intensity’ and ‘health-related quality of life’. Weighting all possible argumentations provided by the panellists, the Steering Committee decided to include these three outcome domains in the COS. As suggested by the OMERACT initiative, also the domain ‘number of deaths’ was included, to incentivize trial teams to report on the occurrence of this very important outcome in every clinical trial. A simple statement, such as ‘no deaths occurred in this clinical trial’ could simply cover this outcome domain. The second step in the development of this COS is to determine which instruments best measure the core outcome domains and this part of the project is currently underway. For now, scientists designing a clinical trial for non-specific LBP can be aware of the existence of a small set of four outcome domains that could be easily included in their trial to facilitate evidence synthesis.
Reference and further reading
“Core outcome domains for clinical trials in non-specific low back pain”
Chiarotto A, Deyo RA, Terwee CB, Boers M, Buchbinder R, Corbin T, Costa LO, Foster NE, Grotle M, Koes BW, Kovacs FM, Lin CW, Maher CG, Pearson AM, Peul WC, Schoene ML, Turk DC, van Tulder MW, Ostelo RW. European Spine Journal 2015 Apr 5. [Epub ahead of print] PMID: 25841358 http://www.ncbi.nlm.nih.gov/pubmed/25841358