An Exploratory Analysis of Gender as a Potential Modifier of Treatment Effect Among Patients in a Randomized...

To identify the potential association of self-reported gender on pain and disability among patients in a randomized controlled trial of integrative acupuncture and spinal manipulation therapy (SMT) for low back pain (LBP).

In the original study, 100 participants with LBP were randomized to receive acupuncture, SMT, or both combined. Eighty completed treatment and were followed for 60 days. Primary outcome measures were the Roland-Morris Disability Questionnaire and numeric pain scales. This study was a secondary analysis and used regression models to estimate and test for gender-specific differences in outcomes from baseline through end of treatment.

Women assigned to acupuncture averaged a 3.8-point reduction in highest LBP vs 2.0 points for SMT, whereas men assigned to SMT averaged a 3.5-point reduction vs 1.8 points for acupuncture (P for interaction = .04). There was a trend toward the same for disability (P for interaction = .12). For women, acupuncture alone led to better outcomes without SMT, and for men, SMT alone led to better outcomes without acupuncture. Women who received acupuncture were more likely to experience 50% or greater reductions in disability and pain, whereas men who received SMT were more likely to experience 50% or greater reductions in disability and pain.

An association was found between self-reported gender and response to LBP treatment. Women demonstrated a greater reduction in pain and disability with acupuncture and men with SMT. Future clinical trials should consider sex as a potential determinant of treatment outcomes for LBP.