Prognostic Factors and Treatment Effect Modifiers for Acupuncture Response in Patients with Neurogenic Claudication of Degenerative Lumbar Spinal Stenosis: Secondary Analysis of a Randomized Controlled Trial.

PURPOSE: Acupuncture has shown its efficacy in improving pain-specific disability among patients with degenerative lumbar spinal stenosis (DLSS) who predominantly present with neurogenic claudication pain symptoms. It is still unclear which group of the patients have better response to acupuncture. This secondary analysis of a randomized controlled trial aimed to identify potential prognostic factors and treatment effect modifiers of response to acupuncture in DLSS patients with neurogenic claudication. PATIENTS AND METHODS: A secondary analysis was conducted based on a multi-center randomized controlled trial, where 196 DLSS patients were randomized to acupuncture or sham acupuncture and 178 completed the 6-week intervention. Responders were defined by a 2-point reduction in the modified Roland-Morris Disability Questionnaire (RMDQ) score from baseline to week 6. Baseline characteristics were summarized using descriptive statistics. Seventeen baseline characteristics were considered as potential prognostic factors of response and subjected to logistic regression analysis. RESULTS: Among the 178 patients included in this secondary analysis, 119 were defined as responders. Treatment assignment (OR 2.0977; 95% CI 1.0300 to 4.2721; p = 0.0412), age (OR 1.0684, 95% CI 1.0176 to 1.1217; p = 0.0078), and Swiss Spinal Stenosis Questionnaire (SSSQ) symptom severity score (OR 1.1270; 95% CI 1.0077 to 1.2606; p = 0.0363) were positively associated with patient response. Patients with a shorter duration of the current episode (OR 0.9384; 95% CI 0.9020 to 0.9764; p = 0.0017) might specifically benefit more from acupuncture. CONCLUSION: DLSS patients with receiving acupuncture, older age, higher SSSQ symptom severity score, and shorter duration of current episode may be more likely to be responder. Duration of current episode modifies the response of acupuncture. These findings provide preliminary evidence to inform patient selection and warrant validation in future studies.