(Cost-)Effectiveness of lower extremity nerve decompression surgery in diabetic subjects: the DeCompression (DECO) trial

Rationale: The peripheral nerves of patients with diabetes are often pathologically swollen, which results in entrapment at places of anatomical narrowing. This results in nerve dysfunction. Surgical treatment of compression neuropathies in the lower extremities (LEND) results in relief of complaints and gain in peripheral nerve function, which may result in less sensory loss (short term) and less associated detrimental effects including foot ulceration and amputations, and lower costs (long term).

Objective: Evaluation of the effectiveness and (cost-)effectiveness of surgical decompression of compressed lower extremity nerves (LEND surgery) compared to patients 'treated' with conventional (non-surgical) care.

Study design: A stratified randomized (1 to 1) controlled trial comparing LEND surgery (intervention) with conventional (non-surgical) care (control strategy). Randomisation is stratified for participating hospital and number of nerves involved. Patients and controls have the same follow-up at 1.5, 3, 6, 9, 12, 18, 24, 36 and 48 months. Participants will be recruited in 12 months and enrolled in eleven affiliated hospitals, in which they receive both intervention or conventional (non-surgical) care and follow-up. Outcome assessors are blinded to group assignment.

Study population: Primary eligibility criteria are patients with diabetes (≥ 18 years old) with complaints of neuropathy and a bilateral Tinel sign at the tarsal tunnel (tibial nerve) as signs of compression neuropathies in the lower extremity.

Intervention (if applicable): In the intervention group, a surgical release of up to four lower extremity nerves (tibial, common, superficial, and deep peroneal nerves) will be carried out. The contralateral leg will be operated three months later.

Main study parameters/endpoints: Complaints (Norfolk QoL-DN), health-related quality of life (EQ-5D, SF-36), plantar sensation, incidence of ulcerations/amputations and resource use during follow-up. The incremental cost-utility ratio will be estimated on the basis of the collected empirical data and a cost-utility model.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The risks associated with participation are related to the surgical procedure. Up to four peripheral nerves in the lower extremity are decompressed, with a contralateral procedure after 12 weeks of the first surgery. The surgical procedure is safe in this vulnerable group, with acceptable low rates of complications rates reported. Reported complications are haemorrhage, wound dehiscence and wound infection(1). Current best diabetes and diabetic foot care are provided to both groups. Nine times a physical examination is carried out in both the intervention and control group, together with quality of life and resource use data collection. The physical examination includes sensory testing, electrodiagnostic measurements and gait analysis, all of which are safe to conduct, with no physical or physiological discomfort associated with participation. To reduce patient burden, not all examinations are executed on all follow-up moments and some outcome measures are assessed in a sub selection of participating centers. Benefit for patients include regular monitoring of their foot status, with early detection of potential threatening conditions.

LEND surgery is a (cost)-effective treatment option for patients with Diabetes and lower extremity compression neuropathy, compared to conventional (non-surgical) care.

First year: inclusion period
Follow up period: 4 years

Lower extremity Nerve Decompression surgery