title: Fixed dynamometry is more sensitive than vital capacity or ALS rating scale.
abstract: BACKGROUND
  Improved outcome measures are essential to efficiently screen the growing number of potential amyotrophic lateral sclerosis (ALS) therapies.
  
  
  METHODS
  This longitudinal study of 100 (70 male) participants with ALS compared Accurate Test of Limb Isometric Strength (ATLIS), using a fixed, wireless load cell, with ALS Functional Rating Scale-Revised (ALSFRS-R) and vital capacity (VC).
  
  
  RESULTS
  Participants enrolled at 5 U.S. sites. Data were analyzed from 66 participants with complete ATLIS, ALSFRS-R, and VC data over at least 3 visits. Change in ATLIS was less variable both within- and among-person than change in ALSFRS-R or VC. Additionally, participants who had normal ALSFRS-R arm and leg function averaged 12 to 32% below expected strength values measured by ATLIS.
  
  
  CONCLUSIONS
  ATLIS was more sensitive to change than ALSFRS-R or VC and could decrease sample size requirements by approximately one-third. The ability of ATLIS to detect prefunctional change has potential value in early trials. Muscle Nerve 56: 710-715, 2017.
authors.affiliation: Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Andres
authors.affiliation: Cedars-Sinai Medical Center, Los Angeles, California, USA.
authors.forename: Margaret Peggy
authors.initials: MP
authors.lastname: Allred
authors.affiliation: Pennsylvania State University, Hershey, Pennsylvania, USA.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Stephens
authors.affiliation: University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Proffitt Bunnell
authors.affiliation: Washington University, St Louis, Missouri, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Siener
authors.affiliation: Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Macklin
authors.affiliation: Pennsylvania State University, Hershey, Pennsylvania, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: Haines
authors.affiliation: University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: English
authors.affiliation: Cedars-Sinai Medical Center, Los Angeles, California, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Fetterman
authors.affiliation: University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Kasarskis
authors.affiliation: Washington University, St Louis, Missouri, USA.
authors.forename: Julaine
authors.initials: J
authors.lastname: Florence
authors.affiliation: Pennsylvania State University, Hershey, Pennsylvania, USA.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Simmons
authors.affiliation: Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Merit E
authors.initials: ME
authors.lastname: Cudkowicz
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D053581:Muscle Strength Dynamometer / Q000592:standards*; D014797:Vital Capacity / Q000502:physiology*
keywords: ALS; ALSFRS-R; longitudinal; outcome measure; strength; vital capacity