Is Nerve Electrophysiology a Robust Primary Endpoint in Clinical Trials of Treatments for Diabetic Peripheral Neuropathy?
Level 1 - systematic review of randomized trials
Systematic review of 21 randomized controlled trials
PubMed 35328284 · doi:10.3390/diagnostics12030731
What was done
A literature search identified 21 double-blind, randomized controlled trials of at least 1 year duration (conducted between 1971 and 2021) evaluating disease-modifying treatments for diabetic peripheral neuropathy (DPN). The authors assessed time-dependent changes in electrophysiology (primarily peroneal motor and sural sensory nerve conduction velocity [NCV] and amplitude) in both placebo and active treatment groups to test the validity of the standard trial power assumption of a 0.5 m/s/year NCV decline.
What was found
The abstract reports no numerical effect sizes or pooled statistics. It found significant variability in both the magnitude and direction (both increases and reductions) of NCV changes within placebo arms across trials, as well as variability driven by the anatomical site of neurophysiological measurement.
Why it matters
Assuming a constant annual decline of 0.5 m/s in NCV can compromise the design and interpretation of DPN clinical trials. Efficacy assessments require placebo-adjusted and placebo-subtracted endpoints, and earlier structural markers of nerve repair (such as corneal confocal microscopy) warrant consideration.
Limits
The abstract provides no quantitative data, effect estimates, or formal meta-analytic heterogeneity metrics. It was restricted to trials of 1 year or longer, and does not report study quality assessments, patient baseline severity distributions, or the specific drug classes evaluated.
Cited by
- supports There are no FDA-approved drugs in the United States to treat the underlying nerve degeneration and loss in diabetic neuropathy.