Prospective, Randomized, Multi-Center Comparative Study Evaluating the Efficacy of Topical Probiotics in Soyabean Concentrate in the Management of Diabetic Foot Ulcers
Conditions: Diabetic Foot Ulcer
Sponsor: Tzu Chi University

Topical Probiotics in a Soybean Concentrate for Diabetic Foot Ulcers: A 
Prospective, Multicentre, Double-Blind, Randomized Controlled Trial 
 
A11002001 
 
29 May 2025 
 
 
 
 
 
 
 
 
 
 

Study Protocol and Statistical Analysis Plan 
 
This multicentre, prospective, double-blind, two-arm, parallel-group 
randomized clinical trial was conducted between January 2022 and June 2024 to 
evaluate the efficacy of a topical probiotic formulation in a soybean concentrate 
compared with placebo in the treatment of diabetic foot ulcers (DFUs) 
(ClinicalTrials.gov Identifier: A11002001). Participants were randomized to 
receive twice-daily application of either investigational product (bottle A) or 
placebo (bottle B), both administered directly to the wound in addition to 
standard care. The contents of each bottle were prepared off-site, and both 
investigators and participants were blinded to treatment allocation. 
The trial was conducted across three hospitals in Taiwan—Dalin Tzu Chi 
Hospital (Chiayi County), Taichung Tzu Chi Hospital (Taichung City), and 
Hualien Tzu Chi Hospital (Hualien City)—by three senior plastic surgeons, 
each with expertise in DFU wound management. The study was conducted in 
accordance with the principles of the Declaration of Helsinki (2013) and Good 
Clinical Practice guidelines. Ethics approval was obtained from the Institutional 
Review Boards of each participating centre. All participants provided written 
informed consent prior to enrolment. The trial was conducted and reported in 
accordance with the Consolidated Standards of Reporting Trials (CONSORT) 
guidelines. 

Study Population 
Eligible participants were adults with a diagnosis of diabetes mellitus and a non-
healing DFU measuring greater than 1 cm² in area, without exposed bone or 
tendon. Full inclusion and exclusion criteria are shown in Table 1. 
Randomization and Intervention 
Block randomization in blocks of 8 was used to assign participants to 1 of 2 
groups: Group 1 received bottle A (topical probiotic in soybean concentrate) 
and Group 2 received bottle B (placebo). Both groups received secondary 
dressing with standard wound care with wet-to-dry dressings. The assigned 
topical treatment was applied directly to the ulcer twice daily throughout the 
treatment phase.  
Outcomes and Data Collection 
Baseline demographic data, medical history, comorbidities, current treatments, 
and wound characteristics were recorded at enrolment. Participants were 
evaluated weekly or biweekly for up to 24 weeks or until complete wound 
healing, whichever occurred first. At each visit, wound surface areas were 
measured and documented using standardized digital photography. Adverse 
events were assessed and documented at each visit. Debridement, when 
necessary, was performed as part of routine clinical care and recorded. 

The primary outcome was the proportion of wounds achieving complete 
healing within 24 weeks. Complete wound healing was defined as full re-
epithelialization without drainage or dressing requirements. Wound healing was 
assessed jointly by the treating plastic surgeon and wound care nurse. Due to 
resource constraints, independent blinded assessors were not employed. 
Secondary outcomes included percentage reduction in wound area, wound 
recurrence rates, incidence and nature of adverse events, and the need for 
additional surgical intervention. Participants who achieved wound healing were 
followed at 2- and 12-weeks post-healing to monitor for recurrence or 
complications. 
Unblinding of treatment allocation was permitted only in the case of a serious 
adverse event (SAE) in which treatment knowledge was required for patient 
safety. All unblinding events were documented and reviewed by the data 
monitoring committee. Otherwise, treatment codes remained concealed until 
study completion. 
 
Statistics 
 

All analyses were performed using IBM SPSS Statistics V25. Continuous 
variables were summarized using means and standard deviations. Categorical 
variables were expressed as frequencies and percentages. Paired t tests were 
used to evaluate differences in continuous variables. Chi-square (χ²) tests were 
applied for comparisons of categorical variables. Survival outcomes were 
assessed using Kaplan–Meier analysis and Cox proportional hazards regression 
modelling. All tests were two-sided, and p values < 0.05 were considered 
statistically significant.