Welcome to the final diabetic foot digest for the year. The paper I have chosen is a follow-up study survey from a multicentre study conducted in the US. The aim was to evaluate the longer-term efficacy of 10 kHz spinal cord stimulation (SCS) in managing painful diabetic neuropathy (PDN) using a follow up survey 2 years after the initial 24-month SENZA study.
In short, the previous study was a RCT that enrolled subjects with PDN symptoms for at least 12 months without relief from standard pharmacological treatments. Subjects were randomised to either conventional drug-based therapies (CT) or SCS with CT. The study protocol permitted CT group to crossover to the SCS arm if pain relief was inadequate after 6 months of treatment. Pain symptoms were recorded using several validated tools including visual analog scale (VAS), quality of life EuroQol 5- Dimensional 5-Level instrument (EQ-5D-5L), and rated their overall change in health status using the 7- point Patient Global Impression of Change (PGIC). Additionally, their HbA1c and BMIs were recorded.
All subjects returned to routine clinical care after completion of SENZA. After 2 years, the 142 subjects receiving SCS were contacted for a post- study survey. Of these, 57 patients consented for the long-term post study survey. Of the 85 not included, 83 were either unreachable or declined and two had died.
Subjects completed a verbal survey reporting on their current lower limb VAS pain intensity on a 0-10 scale using the NRS pain scale to accommodate telephone- based data collection. They also completed the EQ- 5D- 5L and PGIC questionnaires, and provided their most recent HbA1c level and weight measurement (both within the last 6 months). These were compared with the original recorded data
The survey captured subject outcomes at a median of 4.1 years after SCS implantation. The results showed that 76.8% (43 out of 56) subjects reported clinically meaningful pain relief (≥2 points), and 84.6% (44 out of 52) reported improvements in their EQ-5D-5L index score, with a final mean score of 0.825. Additionally, 74.5% (38 of 51) reported feeling “better” or “a great deal better” on the PGIC scale. Interestingly subjects also reported a mean HbA1c level decrease of 0.4% (p=0.027), with a more substantial improvement of 1.6% (p<0.001) in those with type 2 diabetes (T2D) and those with high preimplantation HbA1c (>8%). Significant weight loss was also observed, with a mean reduction of 7.0 kg (p<0.001) in the overall cohort and 8.7 kg (p<0.001) in the subgroup with T2D and a higher BMI at preimplantation (≥35 kg/m2).
SCS for those with moderate to severe PDN symptoms could a justifiable treatment, given the poor long-term pharmacological outcomes. This survey suggests that outcomes from the SENZA 2-year data are not only maintained but may even be improved, especially given that SENZA outcomes reported up to 80% pain reduction, improved sleep and even improvements in neurological parameters. Notable flaws are that it relied on subject self-reporting, rather than investigator obtained. Another significant issue is that reports from 87 of the initial subjects were not obtained; thus, this data must be viewed with care.
