Effect of Baimai ointment on lumbar disc herniation: A multicentre, prospective, randomised, double-blind, placebo-controlled trial

Background: Baimai ointment is a traditional Tibetan topical ointment, which is widely used for various diseases related to the skeletal muscular system and neurological rehabilitation. It has demonstrated good clinical effectiveness. However, there is currently a lack of high-quality evidence regarding the clinical effectiveness of Baimai ointment in treating lumbar disc herniation (LDH). Purpose: In this study, we conducted a prospective, multicenter, double-blind, randomized controlled trial at eight hospitals in China to investigate the clinical effectiveness of Baimai ointment in the treatment of LDH. Methods: Participants aged 18-65 years were diagnosed as LDH and were randomly assigned to receive either Baimai ointment or placebo. The treatment duration was 2 weeks, with 1-week follow-up after treatment. The primary outcome measures included VAS and JOA score. The secondary outcome measures included Likert scale, compliance with health education and the incidence of rescue therapy. The intervention effects on these outcomes were examined by generalized estimating equations (GEE) with baseline measurement as the covariates. All statistical analysis were performed using SPSS 25.0 and Python 3.11. Results: In total, 228 participants were screened from August 25, 2021 to January 31, 2022 at 8 Grade-A tertiary hospitals in China. Finally, 194 eligible participants were randomly assigned to the Baimai ointment group and placebo group in a 1:1 ratio. At the end of 2-week treatment (14th day) and 1-week follow-up after treatment (21st day), the decrease of VAS reached 39.57% (95% CI: 34.29, 44.86) and 36.85% (95% CI: 32.04, 41.66), the decrease in JOA score reached 27.74% (95% CI: 23.05, 32.43) and 26.25 % (95% CI: 20.82, 31.69) in Baimai ointment group. A significant group-by-time interaction indicated a difference for VAS between intervention over time (chi(2) = 26.81, p = 0.020), but JOA score and Likert scale did not reach statistical significance. The adjusted net difference of VAS was statistically significant from 10th day of treatment (p < 0.05). After 2-week treatment, the relief rate of VAS was 30.85% (21.95, 41.34) in Baimai ointment group and 22.73% (14.75, 33.13) in placebo group (chi(2) = 1.53, p = 0.217). It demonstrated Baimai ointment in improving VAS and JOA score was valuable from a clinical view by measuring MCID. Moreover, the Likert scale, the incidence of rescue therapy and compliance with health education did not reach statistical significance. There was no evidence showing that Baimai ointment could cause serious adverse reactions in treating patients with LDH. Conclusion: Baimai ointment demonstrated significantly higher rates of symptom relief compared to the placebo for LDH patients, particularly in terms of relieving pain. Moreover, further high-quality randomized controlled trials were necessary to confirm these positive results. The study protocol is registered with the Clinical Trials Registry (registration number: ISRCTN11912818).