title: [Validation of the functional independence scale].
abstract: OBJECTIVE
  To assess the psychometric quality of an instrument designed to measure functional independence (Functional Independence Scale [FIS]) in several activities of daily living domains and to be applied by trained non-health-related interviewers. The study was carried out in the autonomous region of Madrid in community-dwelling elders.
  
  
  METHODS
  We performed a cross-sectional validation study. In addition to the FIS, Pfeiffer's questionnaire, the Depression Subscale of the Hospital Anxiety and Depression Scale, the Comorbidity Index, the Barthel Index, and EQ-5D were used. These measures were cross-sectionally applied to community-dwelling elders (n=500) and outpatients in a general hospital (n=100) aged 65 years. The following FIS psychometric attributes were analyzed: acceptability, scaling assumptions, internal consistency, construct validity, and precision.
  
  
  RESULTS
  A fully computable FIS total score was obtained in 94.3% of the subjects. A ceiling effect (60.65%), but no floor effect (0.22%) was evident in the community-dwelling elders. No floor or ceiling effects were detected in the hospital sample. Scaling assumptions and internal consistency were satisfactory (item-total correlations: 0.57-0.91; Cronbach's alpha: 0.94). Factor analysis identified three factors that explained 74.3% of the variance. Indexes of convergent, internal, and known-groups validity were satisfactory. The scale's precision, determined by the standard error of measurement (2.49; 95%CI=4.88), was also satisfactory.
  
  
  CONCLUSIONS
  The FIS is an easy-to-use instrument with appropriate metric attributes. This scale can be usefully applied in broad samples of non-institutionalized elders by non-health related personnel.
authors.affiliation: Centro Nacional de Epidemiología, Instituto de Salud Carlos III, Madrid, España. pmartinez@isciii.es
authors.forename: Pablo
authors.initials: P
authors.lastname: Martínez-Martín
authors.forename: Gloria
authors.initials: G
authors.lastname: Fernández-Mayoralas
authors.forename: Belén
authors.initials: B
authors.lastname: Frades-Payo
authors.forename: Fermina
authors.initials: F
authors.lastname: Rojo-Pérez
authors.forename: Roberto
authors.initials: R
authors.lastname: Petidier
authors.forename: Vicente
authors.initials: V
authors.lastname: Rodríguez-Rodríguez
authors.forename: María J
authors.initials: MJ
authors.lastname: Forjaz
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Prieto-Flores
authors.forename: Jesús
authors.initials: J
authors.lastname: de Pedro Cuesta
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics; D011795:Surveys and Questionnaires