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Outcome measures in a cohort of ambulatory adults with spinal muscular atrophy
Author(s) -
Elsheikh Bakri,
King Wendy,
Peng Juan,
Swoboda Kathy J.,
Reyna Sandra P.,
LaSalle Bernard,
Prior Thomas W.,
Arnold W. David,
Kissel John T.,
Kolb Stephen J.
Publication year - 2020
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26756
Subject(s) - isometric exercise , intraclass correlation , sma* , spinal muscular atrophy , medicine , ambulatory , physical therapy , cohort , physical medicine and rehabilitation , cardiology , disease , mathematics , psychometrics , clinical psychology , combinatorics
With the advent of disease‐altering therapies for spinal muscular atrophy (SMA), there is a requirement to better characterize outcome measures, particularly in milder forms of disease. Methods Maximal voluntary isometric contraction testing and 6‐minute walk test (6MWT) performed in ambulatory SMA adults as part of the SMA‐VALIANT trial were analyzed. Test–retest reliability and correlation with other candidate biomarkers and outcomes were investigated. Results Maximal voluntary isometric contraction testing and 6MWT showed good test–retest reliability (intraclass correlation coefficient = 0.98 and 0.85, respectively). Maximal voluntary isometric contraction testing and 6MWT demonstrated very strong correlation ( r = 0.83, P <. 0001), and each correlated with the SMA Functional Rating Scale ( r = 0.7, P < .0001 and r = 0.65, P = .0001, respectively), lean muscle mass ( r = 0.68, P < .0001 and r = 0.56, P = .001, respectively), and ulnar compound muscle action potential ( r = 0.57, P = .0008 and r = 0.47, P = .008, respectively). Discussion Maximal voluntary isometric contraction testing and 6MWT are suitable outcomes for use in ambulatory adults with SMA. Maximal voluntary isometric contraction testing may be preferable because of superior test–retest reliability and closer associations with other outcomes and biomarkers of neuromuscular function.