Symptom Inventory - Multiple Sclerosis (SI-MS) measure of impairment

The Symptom Inventory is a Likert-scaled tool that asks respondents to endorse how severe a particular symptom has been in the last month. Higher scores represent more impairment. Both the 27-item and the 99-item versions of this measure have documented test-retest (r=0.91) and internal consistency reliability (r ranging from 0.66-0.90), as well as criterion and discriminant validity. The subscales of the SI-MS are: (1) visual symptoms; (2) left hemisphere symptoms; (3) right hemisphere symptoms; (4) brain stem and cerebellar symptoms; (5) spinal cord symptoms; (6) non-localizing symptoms.

Performance Scales - Multiple Sclerosis (PS-MS) measure of disability

The Performance Scales - Multiple Sclerosis are 7-level categorical rating scales with subscales for mobility, hand function, vision, fatigue, cognitive, bladder/bowel, sensory, and spasticity disability. Higher scores reflect more disability. The impact on work productivity is assessed with separate items. The measure has documented test-retest reliability (r=0.80), and critierion and discriminant validity.