Measuring function in advanced ALS: validation of ALSFRS-EX extension items
With the aid of assistive technology, some patients with amyotrophic lateral sclerosis (ALS) are able to live for several years past the lowest measurable level of function on the Amyotrophic Lateral Sclerosis Functional Rating Scale - Revised (ALSFRS-R), a widely used end-point in ALS assessment. There is a research need to monitor patient function at the end of life, particularly in the face of severe impairment or 'locked in syndrome'. We used an online community for people with ALS (PALS) (PatientsLikeMe) to construct and pilot a number of new items to add to the ALSFRS-R scale to improve its sensitivity at lower levels of physical function in patients with advanced ALS. Ten new scale items were generated by a survey of PALS with advanced disease. These were added to the existing ALSFRS-R and data were received from 326 PALS at baseline with 169 PALS (52%) completing a 1-week test-retest and 218 PALS (67%) completing a 3-month retest [corrected]. Three new items were selected which conformed to the existing factor structure of the ALFRS-R. These relate to the ability to use fingers to manipulate devices, ability to show emotional expression in the face, and ability to get around inside the home. Real-world validation is the next step to assess the utility of the ALFRS-EX.