another source, or two.
In this case it is the study authors making the determination of what is a relapse.
“Relapse was defined as worsening after improvement with an increase of 4 points or more in the NIS score (see methods – treatment and outcome).”
for more on the NIS-
It would seem there is a standard called “The Neuropathy Impairment Score.” Therefore, any worsening of your own score would seem to indicate a relapse.
Quoting from them:
“Dyck’s gold standard is a composite score he calls the “Neuropathy Impairment Score (Lower Limbs) + 7 Tests” (NIS). The NIS is an evaluation of muscle weakness, a decrease or loss of reflexes and a loss of sensation. There are also scores for the patient’s age, gender, physical fitness and anthropometric features. The “seven tests” are peroneal motor nerve conduction, velocity, peroneal compound muscle action potential, peroneal motor distal latency, sural sensory nerve action potential and tibial motor distal latency, heart-pulse rate decrease with breathing and vibratory detection threshold.1
The comprehensive system also includes algorithms for determining a quantifiable score. This quantifiable score leaves little question as to the diagnosis of DPN. However, for what this system offers in specificity, it is an impossibly difficult system for the private practitioner to utilize and would seem better suited for the specialist or researcher who needs the detail for comparison studies.”