INCAT disability score: a critical analysis of its measurement properties.
BACKGROUND
The INCAT (Inflammatory Neuropathy Cause and Treatment) disability score is a measure of activity limitation. It is used frequently as a primary endpoint in inflammatory polyneuropathy clinical trials. A comprehensive critical analysis of its measurement properties has not been performed.


METHODS
Critical analysis of measurement properties.


RESULTS
The INCAT disability score was derived based on items from Guy's Neurological Disability Scale (GNDS), a disability measure intended for application in multiple sclerosis. Strengths of the INCAT score include evaluation of upper and lower limb dysfunction, ease of administration (feasibility), high face validity, and high reliability. Weaknesses of the scale include concerns about methodological quality of validation studies; failure to properly capture activity limitations due to proximal arm weakness, or fatigue; heavy individual item weighting; and poor sensitivity for detection of clinically important change.


CONCLUSIONS
Although the INCAT scale has been an effective tool in inflammatory polyneuropathy studies, its limitations may warrant development of new scales.
Division of Neurology, Department of Medicine, University of Toronto, 200 Elizabeth Street, Room 5EC-309, Toronto, Ontario, Canada, M5G 2C4.
Ari
A
Breiner
Carolina
C
Barnett
Vera
V
Bril
D020274:Autoimmune Diseases of the Nervous System / Q000150:complications* / Q000175:diagnosis* / Q000628:therapy; D004185:Disability Evaluation; D006233:Persons with Disabilities; D006801:Humans; D015203:Reproducibility of Results; D012720:Severity of Illness Index
CIDP; chronic inflammatory demyelinating polyneuropathy; interpretability; measurement; peripheral neuropathy; reliability; responsiveness; validity