Exercise only, exercise with mechanical traction, or exercise with over-door traction for patients with cervical radiculopathy, with or without consideration of status on a previously described subgrouping rule: a randomized clinical trial.

STUDY DESIGN Randomized clinical trial. OBJECTIVES To examine the effectiveness of cervical traction in addition to exercise for specific subgroups of patients with neck pain. BACKGROUND Cervical traction is frequently used, but its effectiveness has not been adequately examined. Existing studies have failed to target patients most likely to respond. Traction is typically recommended for patients with cervical radiculopathy. A prediction rule has been described to identify a narrower subgroup of patients likely to respond to cervical traction. METHODS Patients with neck pain and signs of radiculopathy were randomized to 4 weeks of treatment with exercise, exercise with mechanical traction, or exercise with over-door traction. Baseline assessment included subgrouping-rule status. The primary outcome measure (Neck Disability Index, scored 0-100) and secondary outcome measure (neck and arm pain intensity) were assessed at 4 weeks, 6 months, and 12 months after enrollment. The primary analyses examined 2-way treatment-by-time interactions. Secondary analyses examined validity of the subgrouping rule by adding 3-way interactions. RESULTS Eighty-six patients (53.5% female; mean age, 46.9 years) were enrolled in the study. Intention-to-treat analysis found lower Neck Disability Index scores at 6 months in the mechanical traction group compared to the exercise group (mean difference between groups, 13.3; 95% confidence interval: 5.6, 21.0) and over-door traction group (mean difference between groups, 8.1; 95% confidence interval: 0.8, 15.3), and at 12 months in the mechanical traction group compared to the exercise group (mean difference between groups, 9.8; 95% confidence interval: 0.2, 19.4). Secondary outcomes favored mechanical traction at several time points. The validity of the subgrouping rule was supported on the Neck Disability Index at the 6-month time point only. CONCLUSION Adding mechanical traction to exercise for patients with cervical radiculopathy resulted in lower disability and pain, particularly at long-term follow-ups. The study protocol was registered at http://clinicaltrials.gov (NCT00979108).