Objectives: To identify the predictive factors of treatment response to acupuncture in patients with fibromyalgia (FM).
Methods: Patients with FM refractory to standard drug therapy underwent eight weekly acupuncture sessions. Significant improvement, defined as a reduction of at least 30% of the revised Fibromyalgia Impact Questionnaire (FIQR), was assessed at the end of the eight weeks (T1) of treatment and three months after the end of treatment (T2). Univariate analysis was conducted to identify predictors of significant improvement at T1 and T2. Variables that resulted to be significantly associated with clinical improvement at univariate analysis were included in multivariate models.
Results: Analyses were conducted on 77 patients (9 males, 11.7%). At T1, significant improvement in FIQR was recorded in 44.2% of patients. At T2, persistent significant improvement was recorded in 20.8% of patients. In the multivariate analysis, predictive variables of treatment failure were tender point count (TPC) (odds ratio [OR] =0.49, 95% confidence interval [95% CI]: 0.28-0.86, p=0.01) and pain magnification (OR=0.68, 95% CI: 0.47-0.99, p=0.04) assessed with the Pain Catastrophising Scale, at T1. At T2, the only predictive variable of treatment failure was concomitant duloxetine use (OR=0.21, 95% CI: 0.05-0.95, p=0.04).
Conclusions: High TPC and a tendency for pain magnification predict immediate treatment failure, while duloxetine therapy predicts it three months after completion of the acupuncture course. The identification of clinical characteristics of unfavourable response to acupuncture could help to implement a cost-effective prevention of treatment failure in FM.