A hospital-based long-term electrophysiological and clinical follow-up study was conducted in 2018 in treated CIDP patients who were studied electrophysiologically for the first time between 1985 and 2006. Motor and sensory nerve conduction studies were carried out at both occasions and the clinical status was evaluated at follow-up using the Inflammatory Rasch-built Overall Disability Scale (I-RODS).

Fourteen CIDP patients were included, five of whom were in remission. The median time since onset of CIDP was 17.5 years (range 12.0 – 30.0) and the median time elapsed between the initial and the follow-up electrophysiological studies was 14.2 years (range 11.4 – 24.2). Twelve patients walked independently, one needed ambulatory support and one had no walking function. The I-RODS was 74.5 (range 28.0 – 100.0) at follow-up. The median combined electrophysiological z-score of motor and sensory action potential amplitudes was -4.7 (range -11.5 – -1.6) at time of diagnosis and -3.4 (range -12.6 – -0.3) at follow-up (p=0.08, ns). Univariate regression analysis revealed a highly significant association between initial axonal loss and current I-RODS, the p-value and coefficient of determination (R²) being <0.0001 and 0.73 respectively. Also, there was a significant association between initial and long-term axonal loss following univariate regression analysis, the p-value and R² being 0.01 and 0.42, respectively.