title: Item analysis of the NHANES ADL instrument in a sample of patients reporting frequent severe headaches.
abstract: OBJECTIVE
  The National Health and Nutrition Examination Surveys (NHANES) activity of daily living (ADL) instrument is a 16-item questionnaire designed to represent the internal latent construct of activities of daily living. The purpose of the present study was to measure selected psychometric properties (dimensionality, internal consistency and individual item response) of the NHANES ADL instrument on a population of patients who reported frequent severe headaches.
  
  
  METHODS
  The study group consisted of 672 attendees of a traditional medical appointment with a report of severe headaches. Data analyses included exploratory factor analysis, internal consistency measures and graded item response theory.
  
  
  RESULTS
  The NHANES ADL instrument is a uni-dimensional and internally consistent measure of activities of daily living. Graded item response theory analyses indicated that all 16 single items were sensitive measures of the latent construct of activities and daily living. Selected items demonstrated high discrimination while others demonstrated moderate discrimination among responses.
  
  
  CONCLUSIONS
  Individual use of selected items of the NHANES ADL instrument may further improve the capacity of the healthcare provider in measuring and recording dysfunction associated with headaches.
authors.affiliation: Duke University Medical Center, Division of Physical Therapy, Durham, NC 27278, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Cook
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pietrobon
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006261:Headache / Q000150:complications*; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000150:complications / Q000503:physiopathology; D009749:Nutrition Surveys; D011594:Psychometrics; D012189:Retrospective Studies; D011795:Surveys and Questionnaires