A collagen matrix with PHMB helped more stalled diabetic foot ulcers close

Design

Multicentre randomised controlled trial

Population

170 adults with hard-to-heal diabetic foot ulcers, 25 US sites

Primary outcome

Complete wound closure within 12 weeks

Effect

42% vs 27%; absolute difference 14.6% (95% CI 0.15% to 27.9%)

This multicentre US trial randomised 170 people with diabetic foot ulcers of 1-25 cm2 that had shrunk by less than 40% over a four-week screening period of good care. They received a native type 1 collagen matrix containing polyhexamethylene biguanide (PHMB) plus standard care, or standard care alone: debridement, cleansing, moisture-balancing dressings and offloading.

Complete closure at 12 weeks, confirmed two weeks later, occurred in 42% with the matrix and 27% with standard care alone, an absolute difference of 14.6% (95% CI 0.15% to 27.9%). Mean area reduction was 75% against 58%. No adverse events were attributed to the matrix.

The result is positive, but the confidence interval only just excludes no effect and the trial was modest in size. The bigger lesson is in the design: ulcers were included only after four weeks of proper care had failed, which is the point at which an adjunct deserves consideration.

• Get the basics right first: debridement, offloading, infection control and vascular assessment.
• Measure the ulcer at each visit; less than 40% shrinkage after four weeks of good care marks a hard-to-heal wound.
• Consider an adjunct such as an antimicrobial collagen matrix only once those basics are in place.
• Reassess for ischaemia and osteomyelitis in any ulcer that stalls.

Why it matters

It gives a measured trigger for escalating care rather than switching dressings at random.

Don't overread it

The benefit only just reached significance in 170 patients; the true effect could be small.

The statistics, in plain English

An absolute difference of 14.6% means about 15 more ulcers closed per 100 treated. But the confidence interval runs from almost zero (0.15%) to 28%, so the result is compatible with a tiny benefit.

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