title: Comparison of self-report-based and physical performance-based frailty definitions among patients receiving maintenance hemodialysis.
abstract: BACKGROUND
  A well-accepted definition of frailty includes measurements of physical performance, which may limit its clinical utility.
  
  
  METHODS
  In a cross-sectional study, we compared prevalence and patient characteristics based on a frailty definition that uses self-reported function to the classic performance-based definition and developed a modified self-report-based definition.
  
  
  METHODS
  Prevalent adult patients receiving hemodialysis in 14 centers around San Francisco and Atlanta in 2009-2011.
  
  
  METHODS
  Self-report-based frailty definition in which a score lower than 75 on the Physical Function scale of the 36-Item Short Form Health Survey (SF-36) was substituted for gait speed and grip strength in the classic definition; modified self-report definition with optimized Physical Function score cutoff points derived in a development (one-half) cohort and validated in the other half.
  
  
  METHODS
  Performance-based frailty defined as 3 of the following: weight loss, weakness, exhaustion, low physical activity, and slow gait speed.
  
  
  RESULTS
  387 (53%) patients were frail based on self-reported function, of whom 209 (29% of the cohort) met the performance-based definition. Only 23 (3%) met the performance-based definition of frailty only. The self-report definition had 90% sensitivity, 64% specificity, 54% positive predictive value, 93% negative predictive value, and 72.5% overall accuracy. Intracellular water per kilogram of body weight and serum albumin, prealbumin, and creatinine levels were highest among nonfrail individuals, intermediate among those who were frail by self-report, and lowest among those who also were frail by performance. Age, percentage of body fat, and C-reactive protein level followed an opposite pattern. The modified self-report definition had better accuracy (84%; 95% CI, 79%-89%) and superior specificity (88%) and positive predictive value (67%).
  
  
  CONCLUSIONS
  Our study did not address prediction of outcomes.
  
  
  CONCLUSIONS
  Patients who meet the self-report-based but not the performance-based definition of frailty may represent an intermediate phenotype. A modified self-report definition can improve the accuracy of a questionnaire-based method of defining frailty.
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; Division of Nephrology, University of California, San Francisco, CA; Nephrology Section, San Francisco VA Medical Center, University of California, San Francisco, CA; Department of Epidemiology & Biostatistics, University of California, San Francisco, CA. Electronic address: kirsten.johansen@ucsf.edu.
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Johansen
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; University of California, San Francisco Division of Nephrology, University of California, Davis, CA.
authors.forename: Lorien S
authors.initials: LS
authors.lastname: Dalrymple
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; Division of Nephrology, University of California, San Francisco, CA; Nephrology Section, San Francisco VA Medical Center, University of California, San Francisco, CA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Delgado
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; University of California, San Francisco Division of Nephrology, University of California, Davis, CA.
authors.forename: George A
authors.initials: GA
authors.lastname: Kaysen
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; Department of Epidemiology & Biostatistics, University of California, San Francisco, CA.
authors.forename: John
authors.initials: J
authors.lastname: Kornak
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; Department of Epidemiology & Biostatistics, University of California, San Francisco, CA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Grimes
authors.affiliation: United States Renal Data System Nutrition Special Studies Center, University of California, San Francisco, CA; Division of Nephrology, Stanford University School of Medicine, Palo Alto, CA.
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Chertow
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001247:Asthenia / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D001823:Body Composition; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000503:physiopathology / Q000523:psychology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D010809:Physical Fitness; D011237:Predictive Value of Tests; D015995:Prevalence; D006435:Renal Dialysis / Q000009:adverse effects / Q000379:methods; D057566:Self Report; D012680:Sensitivity and Specificity; D018434:Sickness Impact Profile; D014481:United States / Q000453:epidemiology; D015431:Weight Loss
keywords: Frailty; end-stage renal disease (ESRD); hemodialysis; physical activity; physical function; physical performance; self-reported function