J Neuromusculoskeletal System 2000 (Summer); 8 (2): 39–48
Cheryl Hawk, D.C., Ph.D., Cynthia R. Long, Ph.D.
Parker Research Institute,
Dallas, TX 75229, USA.
Development of an appropriate placebo treatment is one of the major challenges in designing chiropractic clinical trials. To date, such trials have not provided convincing eveidence that both 1) the manual lacebo did in fact act as a placebo, and 2) patients were successfully blinded to treatment group assignment. In order to develop a manual placebo treatment that will satisfy these criteria, the authors first conducted a pilot study with a 2x2 factorial design to assess recruitment and study protocols and refine the study design. Thirty-two patients with subacute or chronic low back pain were randomly assigned to group A (flexion-distration technique and trigger point therapy), group B (sham adjustment and effleurage massage), group C (flexion-distractioin and effleurage), or group D (sham adjustment and trigger point therapy) for 6 weeks of treatment. The Roland Morris Questionnaire (RMQ) and the Pain Disability Index (PDI) were the outcome instruments of primary interest. RMQ median score changes were similar across groups. PDI median score changes at week 3 were greatest in group A, less in groups C and D, and least in group B. At week 6, group B still showed less change than the others. The results of this study were used to refine several important aspects of the proposed placebo development study.