title: Migrating from a legacy fixed-format measure to CAT administration: calibrating the PHQ-9 to the PROMIS depression measures.
abstract: OBJECTIVE
  We provide detailed instructions for analyzing patient-reported outcome (PRO) data collected with an existing (legacy) instrument so that scores can be calibrated to the PRO Measurement Information System (PROMIS) metric. This calibration facilitates migration to computerized adaptive test (CAT) PROMIS data collection, while facilitating research using historical legacy data alongside new PROMIS data.
  
  
  METHODS
  A cross-sectional convenience sample (n = 2,178) from the Universities of Washington and Alabama at Birmingham HIV clinics completed the PROMIS short form and Patient Health Questionnaire (PHQ-9) depression symptom measures between August 2008 and December 2009. We calibrated the tests using item response theory. We compared measurement precision of the PHQ-9, the PROMIS short form, and simulated PROMIS CAT.
  
  
  RESULTS
  Dimensionality analyses confirmed the PHQ-9 could be calibrated to the PROMIS metric. We provide code used to score the PHQ-9 on the PROMIS metric. The mean standard errors of measurement were 0.49 for the PHQ-9, 0.35 for the PROMIS short form, and 0.37, 0.28, and 0.27 for 3-, 8-, and 9-item-simulated CATs.
  
  
  CONCLUSIONS
  The strategy described here facilitated migration from a fixed-format legacy scale to PROMIS CAT administration and may be useful in other settings.
authors.affiliation: General Internal Medicine, University of Washington, Box 359780, Harborview Medical Center, 325 Ninth Ave, Seattle, WA 98104, USA gibbonsl@u.washington.edu
authors.forename: Laura E
authors.initials: LE
authors.lastname: Gibbons
authors.forename: Betsy J
authors.initials: BJ
authors.lastname: Feldman
authors.forename: Heidi M
authors.initials: HM
authors.lastname: Crane
authors.forename: Michael
authors.initials: M
authors.lastname: Mugavero
authors.forename: James H
authors.initials: JH
authors.lastname: Willig
authors.forename: Donald
authors.initials: D
authors.lastname: Patrick
authors.forename: Joseph
authors.initials: J
authors.lastname: Schumacher
authors.forename: Michael
authors.initials: M
authors.lastname: Saag
authors.forename: Mari M
authors.initials: MM
authors.lastname: Kitahata
authors.forename: Paul K
authors.initials: PK
authors.lastname: Crane
mesh_terms: D000328:Adult; D000368:Aged; D000407:Alabama; D001331:Automation; D002138:Calibration; D003430:Cross-Sectional Studies; D003863:Depression / Q000175:diagnosis*; D003936:Diagnosis, Computer-Assisted; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D011795:Surveys and Questionnaires; D014861:Washington; D014894:Weights and Measures; D055815:Young Adult