Psychometric evaluation of a new sensory scale in immune-mediated polyneuropathies

Objective: To perform a psychometric evaluation of the inflammatory neuropa thy cause and treatment (INCAT) sensory sumscore (ISS) in sensory-motor imm une-mediated polyneuropathies. This new sensory scale was evaluated to stri ve for uniformity in assessing sensory deficit in these disorders. Methods: The LSS comprises vibration and pinprick sense plus a two-point discrimina tion value and ranges from 0 (normal sensation) to 20 (maximum sensory defi cit). Before its clinical use, a panel of expert neurologists concluded tha t the ISS has face and content validity. The construct validity of the ISS was investigated by correlation and regression studies with additional scal es (Nine-Hole Peg Test, 10-Meter Walking Test, a disability sumscore). All scales were applied in 113 patients with a stable neurologic condition (83 patients who experienced Guillain-Barre syndrome [GBS] in the past, 22 with chronic inflammatory demyelinating polyneuropathy [CIDP], 8 patients with a monoclonal gammopathy associated polyneuropathy), and 10 patients with re cently diagnosed GBS or CIDP with changing clinical conditions. Reliability of the ISS was evaluated in the stable patients. Its responsiveness was in vestigated in the patients examined longitudinally. Results: A moderate to good validity was obtained for the ISS (stable group: r = 0.38 to 0.56, p l ess than or equal to 0.006; longitudinal group: R = 0.60 to 0.82, p less th an or equal to 0.007, except fbr the association with the 10-Meter Walking Test [p = 0.08]). Acceptable internal consistency, and inter- and intraobse rver reliability were demonstrated for the ISS (alpha = 0.68 to 0.87; R = 0 .85 to 0.89, p < 0.0001). Standardized response mean scores for the ISS wer e high (greater than or equal to 0.8), indicating good responsiveness. Conc lusions: All psychometric requirements are provided for the the inflammator y neuropathy cause and treatment sensory sumscore. The use of this scale is therefore suggested for bedside evaluation of sensory deficit in the indiv idual patient with a sensory-motor immune-mediated polyneuropathy as well a s in clinical trials.