title: Evaluating task modification as an objective measure of functional limitation: repeatability and comparability.
abstract: BACKGROUND
  Modification of everyday tasks in older adults is associated with risk of deleterious health outcomes. The purpose of this study was to develop a task modification scale to examine its reliability and comparability to timed performance and common measures of physical function and impairment.
  
  
  METHODS
  Eighty-two (21 men, 61 women) older adults (74.4 +/- 8.2 years) were observed performing a chair rise (sitting heights: 43 cm, 38 cm, and 30 cm), stair ascent/descent, and kneel and supine rise tasks. Six hierarchically ranked categories (0-5) of modification were created for each task and then summed across tasks (summary modification [MOD] score: range 0-35). Comparisons were made with timed performance, knee extension strength, single-leg balance, self-reported function, five chair stands, and gait speed.
  
  
  RESULTS
  Inter-rater reliability (intra-class correlation = 0.98) and participant repeatability (intra-class correlation = 0.92) of the MOD score were excellent. Ninety-six percent of participants modified at least one task (MOD score: 10.5 +/- 7.51, range 0-27). After adjusting for task modification, timed performance showed a lower association with gait speed (time vs MOD score, semipartial r2 = 0.31 vs 0.68), strength (semipartial r2 = 0.14 vs 0.65), and single-leg balance (semipartial r2 = 0.10 vs 0.40) than did the MOD score. The MOD score showed higher correlations with muscle strength and balance impairment than did other measures of functional limitation such as gait speed, time to complete five chair stands, and self-reported physical function.
  
  
  CONCLUSIONS
  Documentation of task modification is reliable across raters and repeatable within participants; in addition, it compares well with other measures of physical function and impairment. Task modification reveals important and intuitive information regarding physical limitation, and deserves greater attention.
authors.affiliation: Department of Exercise Science, Syracuse University, New York, USA. maninit@mail.nih.gov
authors.forename: Todd M
authors.initials: TM
authors.lastname: Manini
authors.forename: Summer B
authors.initials: SB
authors.lastname: Cook
authors.forename: Tom
authors.initials: T
authors.lastname: VanArnam
authors.forename: Moshe
authors.initials: M
authors.lastname: Marko
authors.forename: Lori
authors.initials: L
authors.lastname: Ploutz-Snyder
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D012044:Regression Analysis; D015203:Reproducibility of Results