Defining chronic low back pain (CLBP) and creating consensus about a set of core outcome measures consistently used by researchers in the field has been a goal of the spine community for well over a decade, if not longer.1 Recently the NIH created a Research Task Force (RTF) to define CLBP and related conditions and create a core dataset including baseline characteristics and outcomes that should be included in all studies on the topic. They defined CLBP as “a back pain problem that has persisted at least 3 months and has resulted in pain on at least half the days in the past 6 months.” While they were charged with defining and categorizing related conditions such as spinal stenosis, sciatica, and instability, the RTF determined there were not clear diagnostic criteria for these subcategories within the CLBP spectrum, so it was not possible to rigorously define them. The RTF did create a 40 question core dataset that all CLBP studies should record as a minimal baseline dataset, with a major focus of the questionnaire being CLBP “impact stratification”. This included the domains of pain intensity, pain interference, and function and drew on many items from the PROMIS and STarT Back questionnaires. In terms of a core outcomes set, they did not recommend any specific “legacy” measures such as the Oswestry Disability Index or Roland-Morris Disability Questionnaire, but they did recommend using their proposed “impact stratification score” and other outcome measures relevant to the goals of the study. Additionally, they recommended the use of composite outcome measures (i.e. looking at multiple domains such as pain, function, and return to work) as well as responder analysis in which the proportion of study participants reaching a defined threshold of improvement was determined in addition to the mean improvement. The RTF recommended that all NIH grant submissions include this minimal core dataset in addition to specific outcome measures more relevant to the question being studied.
The RTF should be applauded for attempting to create order in the disjointed world of CLBP research, and their difficulties in accomplishing some of the tasks reflects the lack of consensus around and understanding of CLBP. A major shortcoming of the report is its inability to define subcategories within CLBP such as spinal stenosis, disk herniation, degenerative and isthmic spondylolisthesis, degenerative scoliosis, degenerative disk disease, etc.2 All of these conditions have distinct pathophysisiology, history and physical exam characteristics, and imaging findings. Additionally, they are treated differently and have different expected outcomes. While the proposed minimum core dataset is a reasonable place to start for all CLBP studies, it would be helpful for the research community to agree on definitions of the subcategories as well as the most appropriate outcome measures for each of these. The novel CLBP “impact stratification score” may be promising, but given the large number of legacy outcome measures already in use as well as the newer PROMIS and STarT Back questionnaires, is seems unlikely that this unvalidated outcome measure will become the gold standard for CLBP research anytime soon. The RTF created a document that should help researchers agree on a minimum dataset that should be gathered for all CLBP studies, but it also demonstrated that the spine research community has relatively fundamental work to do in defining the key conditions and the best outcome measures for these.
Please read the RTF’s report currently available on the Spine website. Does this change your view on the definition of CLBP or the best outcome measures to study it? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor
1. Bombardier C. Outcome assessments in the evaluation of treatment of spinal disorders: summary and general recommendations. Spine (Phila Pa 1976) 2000;25:3100-3.
2. Abraham I, Killackey-Jones B. Lack of evidence-based research for idiopathic low back pain: the importance of a specific diagnosis. Arch Intern Med 2002;162:1442-4; discussion 7.