title: Refining Low Physical Activity Measurement Improves Frailty Assessment in Advanced Lung Disease and Survivors of Critical Illness.
abstract: BACKGROUND
  The frail phenotype has gained popularity as a clinically relevant measure in adults with advanced lung disease and in critical illness survivors. Because respiratory disease and chronic illness can greatly limit physical activity, the measurement of participation in traditional leisure time activities as a frailty component may lead to substantial misclassification of frailty in pulmonary and critical care patients.
  
  
  OBJECTIVE
  To test and validate substituting the Duke Activity Status Index (DASI), a simple 12-item questionnaire, for the Minnesota Leisure Time Physical Activity (MLTA) questionnaire, a detailed questionnaire covering 18 leisure time activities, as the measure of low activity in the Fried frailty phenotype (FFP) instrument.
  
  
  METHODS
  In separate multicenter prospective cohort studies of adults with advanced lung disease who were candidates for lung transplant and older survivors of acute respiratory failure, we assessed the FFP using either the MLTA or the DASI. For both the DASI and MLTA, we evaluated content validity by testing floor effects and construct validity through comparisons with conceptually related factors. We tested the predictive validity of substituting the DASI for the MLTA in the FFP assessment using Cox models to estimate associations between the FFP and delisting/death before transplant in those with advanced lung disease and 6-month mortality in older intensive care unit (ICU) survivors.
  
  
  RESULTS
  Among 618 adults with advanced lung disease and 130 older ICU survivors, the MLTA had a substantially greater floor effect than the DASI (42% vs. 1%, and 49% vs. 12%, respectively). The DASI correlated more strongly with strength and function measures than did the MLTA in both cohorts. In models adjusting for age, sex, comorbidities, and illness severity, substitution of the DASI for the MLTA led to stronger associations of the FFP with delisting/death in lung transplant candidates (FFP-MLTA hazard ratio [HR], 1.42; 95% confidence interval [CI], 0.55-3.65; FFP-DASI HR, 2.99; 95% CI, 1.03-8.65) and with mortality in older ICU survivors (FFP-MLTA HR, 2.68; 95% CI, 0.62-11.6; FFP-DASI HR, 5.71; 95% CI, 1.34-24.3).
  
  
  CONCLUSIONS
  The DASI improves the construct and predictive validity of frailty assessment in adults with advanced lung disease or recent critical illness. This simple questionnaire should replace the more complex MLTA in assessing the frailty phenotype in these populations.
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Matthew R
authors.identifier: http://orcid.org/0000-0003-4670-3433
authors.initials: MR
authors.lastname: Baldwin
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Jonathan P
authors.identifier: http://orcid.org/0000-0003-0224-7472
authors.initials: JP
authors.lastname: Singer
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Debbie
authors.initials: D
authors.lastname: Huang
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Jessica
authors.initials: J
authors.lastname: Sell
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Wendy C
authors.initials: WC
authors.lastname: Gonzalez
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Pollack
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Mathew S
authors.initials: MS
authors.lastname: Maurer
authors.affiliation: 3 Department of Surgery, College of Physicians & Surgeons, and.
authors.forename: Frank F
authors.initials: FF
authors.lastname: D'Ovidio
authors.affiliation: 3 Department of Surgery, College of Physicians & Surgeons, and.
authors.forename: Matthew
authors.initials: M
authors.lastname: Bacchetta
authors.affiliation: 3 Department of Surgery, College of Physicians & Surgeons, and.
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Sonett
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Selim M
authors.initials: SM
authors.lastname: Arcasoy
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Lori
authors.initials: L
authors.lastname: Shah
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.
authors.forename: Hilary
authors.initials: H
authors.lastname: Robbins
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Hays
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Jasleen
authors.initials: J
authors.lastname: Kukreja
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: John R
authors.initials: JR
authors.lastname: Greenland
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Rupal J
authors.initials: RJ
authors.lastname: Shah
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Lorriana
authors.initials: L
authors.lastname: Leard
authors.affiliation: 4 Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors.forename: Matthew
authors.initials: M
authors.lastname: Morrell
authors.affiliation: 4 Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Gries
authors.affiliation: 2 Department of Medicine, University of California-San Francisco, San Francisco, California.
authors.forename: Patricia P
authors.initials: PP
authors.lastname: Katz
authors.affiliation: 5 Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Christie
authors.affiliation: 5 Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Diamond
authors.affiliation: 1 Department of Medicine, College of Physicians & Surgeons.|6 Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York.
authors.forename: David J
authors.identifier: http://orcid.org/0000-0001-5258-0228
authors.initials: DJ
authors.lastname: Lederer
mesh_terms: D000368:Aged; D016638:Critical Illness / Q000628:therapy; D004185:Disability Evaluation; D015444:Exercise; D005260:Female; D000073496:Frailty / Q000175:diagnosis*; D006801:Humans; D007362:Intensive Care Units / Q000458:organization & administration; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D008171:Lung Diseases / Q000401:mortality* / Q000503:physiopathology* / Q000628:therapy; D016040:Lung Transplantation; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D017741:Survivors; D014481:United States
keywords: critical illness; disability; frailty; lung transplantation; motor activity