title: Criterion-Referenced Values of Grip Strength and Usual Gait Speed Using Instrumental Activities of Daily Living Disability as the Criterion.
abstract: OBJECTIVE
  Current evidence suggests that grip strength and usual gait speed (UGS) are important predictors of instrumental activities of daily living (IADL) disability. Knowing the optimum cut points of these tests for discriminating people with and without IADL disability could help clinicians or researchers to better interpret the test results and make medical decisions. The purpose of this study was to determine the cutoff values of grip strength and UGS for best discriminating community-dwelling older adults with and without IADL disability, separately for men and women, and to investigate their association with IADL disability.
  
  
  METHODS
  We conducted secondary data analysis on a national dataset collected in the Sarcopenia and Translational Aging Research in Taiwan (START). The data used in this study consisted of health data of 2420 community-dwelling older adults 65 years and older with no history of stroke and with complete data. IADL disability was defined as at least 1 IADL item scored as "need help" or "unable to perform." Receiver operating characteristics analysis was used to estimate the optimum grip strength and UGS cut points for best discriminating older adults with/without IADL disability. The association between each physical performance (grip strength and UGS) and IADL disability was assessed with odds ratios (ORs).
  
  
  CONCLUSIONS
  With IADL disability as the criterion, the optimal cutoff values of grip strength were 28.7 kg for men and 16.0 kg for women, and those for UGS were 0.76 m/s for men and 0.66 m/s for women. The grip strength test showed satisfactory discriminant validity (area under the curve > 0.7) in men and a strong association with IADL disability (OR > 4). Our cut points using IADL disability as the criterion were close to those indicating frailty or sarcopenia.
  
  
  CONCLUSIONS
  Our reported cutoffs can serve as criterion-referenced values, along with those previously determined using different indicators, and provide important landmarks on the performance continua of older adults' grip strength and UGS. These landmarks could be useful in interpreting test results, monitoring changes in performance, and identifying individuals requiring timely intervention. For identifying older adults at risk of IADL disability, grip strength is superior to UGS.
authors.affiliation: Taichung Hospital, Ministry of Health and Welfare, and Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Meng-Chih
authors.initials: MC
authors.lastname: Lee
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan.
authors.forename: Chih-Cheng
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan.
authors.forename: Yi-Fen
authors.initials: YF
authors.lastname: Tsai
authors.affiliation: Department of Family Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Department of Family Medicine, China Medical University & Hospital, Taichung, Taiwan.
authors.forename: Cheng-Chieh
authors.initials: CC
authors.lastname: Lin
authors.affiliation: School of Physical Therapy & Center for Education and Research on Geriatrics and Gerontology, Chung Shan Medical University, and Physical Therapy Room, Chung Shan Medical University Hospital, Taichung Taiwan.
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Wang
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D006233:Persons with Disabilities; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D057187:Independent Living; D008297:Male; D026741:Physical Therapy Modalities; D012372:ROC Curve; D012016:Reference Values; D012307:Risk Factors; D055948:Sarcopenia; D000072797:Walking Speed / Q000502:physiology*