title: Rasch analysis reveals comparative analyses of activities of daily living/instrumental activities of daily living summary scores from different residential settings is inappropriate.
abstract: To internally validate a 15-item dichotomous activities of daily living (ADL) and instrumental activities of daily living (IADL) index.
  
  
  
  Data were extracted from The Older Persons and Informal Caregivers Survey Minimum DataSet (TOPICS-MDS). Using Rasch modeling, six aspects of the ADL/IADL scale were assessed: (1) overall fit, (2) internal consistency, (3) individual item and person fit, (4) local dependency, (5) targeting, and (6) differential item functioning (DIF) (RUMM 2030). All analyses were stratified by living situation [community-dwelling (n = 21,926) or residential care facility (n = 2,458)].
  
  
  
  In both settings, "eating" was the easiest activity on the scale and "performing household tasks" was the most difficult activity. However, based on the location on the logit scale, the level of difficulty for certain items varied between residential settings, suggesting summary scores are not equivalent between these settings. DIF by gender and age group was observed for several items, indicating potential measurement bias in the scale.
  
  
  
  Unless adjustments are undertaken, ADL/IADL summary scores retrieved from older persons residing in the community or residential care facilities should not be directly compared. This 15-item scale is poorly targeted for a community-dwelling older population, underscoring the need for items with improved discriminative ability.
authors.affiliation: Department of Geriatric Medicine, Radboud University Medical Center, Reinier Postlaan 4, 6525 CG Nijmegen, The Netherlands; National Perinatal Epidemiology Centre, 5(th) Floor, Cork University Maternity Hospital, Wilton, Cork, Ireland. Electronic address: jennifer.lutomski@radboudumc.nl.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Lutomski
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
authors.forename: Paul F M
authors.initials: PF
authors.lastname: Krabbe
authors.affiliation: Department of Public Health and Primary Care, Leiden University Medical Center, Hippocratespad 21, 2333 RC Leiden, The Netherlands.
authors.forename: Wendy P J
authors.initials: WP
authors.lastname: den Elzen
authors.affiliation: Department of Geriatric Medicine, Radboud University Medical Center, Reinier Postlaan 4, 6525 CG Nijmegen, The Netherlands.
authors.forename: Marcel G M
authors.initials: MG
authors.lastname: Olde-Rikkert
authors.affiliation: Department of Public Health, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands.
authors.forename: Ewout W
authors.initials: EW
authors.lastname: Steyerberg
authors.affiliation: Department of General Practice and Elderly Care Medicine, EMGO+ Institute for Health and Care Research, VU Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
authors.forename: Maaike E
authors.initials: ME
authors.lastname: Muntinga
authors.affiliation: Department of General Practice, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Universiteitweg 100, 3584 CG Utrecht, The Netherlands.
authors.forename: Nienke
authors.initials: N
authors.lastname: Bleijenberg
authors.affiliation: Department of Health Services Research, School for Public Health and Primary Care (CAPHRI), Maastricht University, Duboisdomein 30, 6229 GT Maastricht, The Netherlands.
authors.forename: Gertrudis I J M
authors.initials: GI
authors.lastname: Kempen
authors.affiliation: Department of Geriatric Medicine, Radboud University Medical Center, Reinier Postlaan 4, 6525 CG Nijmegen, The Netherlands.
authors.forename: René J F
authors.initials: RJ
authors.lastname: Melis
mesh_terms: D000203:Activities of Daily Living; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D015577:Geriatric Assessment / Q000379:methods* / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D015233:Models, Statistical; D009426:Netherlands; D015203:Reproducibility of Results; D012111:Residence Characteristics; D012112:Residential Facilities; D017678:Sex Distribution
keywords: Activities of daily living; Data sharing; Geriatrics; Item response theory; Rasch model; Survey methodology