Photobiomodulation therapy combined with static magnetic field is better than placebo in patients with fibromyalgia: a randomized placebo-controlled trial

BACKGROUND: Fibromyalgia is a syndrome characterized by generalized chronic pain and tenderness in specific areas. Photobiomodulation therapy (PBMT) using low-level laser therapy and/or light emitting diode therapy is an electrophysical agent that can be used alone or together with a static magnetic field (PBMT-sMF) to promote analgesia in several health conditions. Little evidence exists regarding the effects of using PBMT and PBMT-sMF in patients with fibromyalgia; this evidence is conflicting. AIM: We aimed to investigate the effects of using PBMT-sMF versus a placebo on reduction of the degree-of-pain rating, impact of fibromyalgia, pain intensity, and satisfaction with treatment in patients with fibromyalgia. DESIGN: A prospectively registered, monocentric, randomized placebo-controlled trial, with blinding of patients, therapists, and assessors, was performed. SETTING: The study was conducted at the Laboratory of Phototherapy and Innovative Technologies in Health (LaPIT) in Brazil, between March and October 2020. POPULATION: Ninety female patients with fibromyalgia were randomized to undergo either PBMT-sMF (N.=45) or placebo (N.=45) treatment. METHODS: Patients from both groups received nine treatment sessions, three times a week, for 3 weeks. Clinical outcomes were collected at baseline, the end of treatment, and at the follow-up appointment 4 weeks post-treatment. The primary outcome was the degree-of-pain rating, measured by the reduction of the tender point count. RESULTS: A decrease in the degree-of-pain rating was observed in patients allocated to the PBMT-sMF group, decreasing the number of tender points when compared to placebo group at the end of treatment (P