Studies of patients with chronic low back pain (CLBP) have limitations. There is general agreement that a per patient responder index might provide better insight into response given the heterogeneity of the disease. A CLBP responder index, composite of clinical endpoints with specific improvement criteria, was developed to evaluate whether a particular patient responded. Identification of the components of the index involved a 4-step process: (1) a literature review to identify measures in CLBP studies; (2) focus groups of CLBP patients and clinical expert interviews to determine perceived important outcomes; (3) potential responder indices were developed using data from three 12-week placebo-controlled celecoxib CLBP studies (developmental database); (4) candidate responder indices were validated using data from two 12-week placebo-controlled valdecoxib CLBP studies (validation database). Candidate responder indices from the development database were selected on the basis of effect size and high chi-square test values, resulting in 5 endpoints being selected for additional testing: LBP Intensity (visual analog scale [VAS]), Patient’s Global Assessment (PGA), Pain Right Now (modified Brief Pain Inventory-short form [mBPI-sf]), Roland Morris Disability Questionnaire (RMDQ) total score, and Satisfaction with Medication (Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form [Q-LESQ-SF]). Improvement criteria were then added to construct initial responder indices defined as changes in single endpoints and combinations of multiple endpoints: both 30% and 50% improvements in LBP VAS and Pain Right Now, and 30% improvement or no worsening in PGA, RMDQ, and Satisfaction with Medication. Following additional testing in the validation population, the resulting preliminary responder index was≥ 30% improvement in LBP and PGA, and no worsening (≤ 20%) in RMDQ total score. In conclusion, we have developed and tested a measure of response to CLBP therapy that is clinically relevant to patients, easy to administer, and provides a means for standardizing assessments across clinical trials.
