Objective
To assess the therapeutic efficacy of local injections with Botulinum Toxin Type-A (Btx-A) in improving blood flow to the hands of patients with Raynaud's Phenomenon (RP) secondary to scleroderma.
Methods
In this randomized, double-blind, placebo-controlled clinical trial (ClinicalTrials.gov #NCT02165111), patients with scleroderma-associated RP received Btx-A (50 units in 2.5 mL) in one randomly selected hand and sterile saline (2.5 mL) in the opposite hand. Follow-up at 1 and 4 months post-injection included Laser Doppler Imaging (LDI) of hands, patient-reported outcomes, and physical exam. We compared outcomes using paired t-test and population average generalized models with generalized estimating equations.
Results
Of 40 patients enrolled, 25 had limited and 15 diffuse scleroderma. From baseline to 1-month follow-up, there was a greater reduction in average blood flow in Btx-A hands compared to placebo. The model estimated that this difference was statistically significant (average difference: -30.08 flux units, 95% CI: -56.19 to -3.98, p-value=0.024). This difference was mainly influenced by patients with longstanding RP and diffuse scleroderma. Change in blood flow at 4-month follow-up was not significantly different between groups. Clinical measures improved slightly for Btx-A hands in QuickDASH, McCabe score, pain VAS, and Raynaud's Condition Score.
Conclusion
Our laboratory-based LDI flow data do not support using Btx-A to treat RP in all scleroderma patients. The secondary clinical outcomes suggest some positive, but questionably clinically meaningful effect. The role of Btx-A in treating RP should be further studied with more homogeneous patient populations and in unique clinical situations like acute digital ischemia.