title: The reliability and validity of the self-reported patient-specific index for total hip arthroplasty.
abstract: BACKGROUND
  The Patient-Specific Index is unique in that it reflects how individual patients weigh concerns in rating the outcome of total hip arthroplasty. The Patient-Specific Index was originally administered by an interviewer, which is not always feasible and can be costly. The purposes of the present study were (1) to create a self-reported version of the Patient-Specific Index, (2) to determine the reliability of this new self-reported version, and (3) to determine the relationship between the scores on the new self-reported version and those on the original interviewer-administered version.
  
  
  METHODS
  A self-reported version of the Patient-Specific Index was developed, and a pilot test was performed on ten patients. Patients who were scheduled for a total hip arthroplasty or who had recently had a total hip arthroplasty were eligible for the reliability and validity testing. A copy of the new self-reported Patient-Specific Index was mailed to the patients, and they completed it independently. The patients' ratings of the importance and severity of twenty-four concerns prior to total hip arthroplasty were added together to create a summary Patient-Specific Index score. To determine test-retest reliability, patients completed the self-reported Patient-Specific Index a second time, two weeks later. To determine criterion validity, participants also completed the interviewer-administered Patient-Specific Index.
  
  
  RESULTS
  Fifty-five patients completed the study. The random-effects intraclass correlation test-retest coefficient was 0.79 (greater than 0.75 represents excellent reliability). The mean Patient-Specific Index scores on the self-reported version and on the interviewer-administered version were 173 and 165 points, respectively (Student t test, p = 0.45). The self-reported Patient-Specific Index was concordant with the interviewer-administered Patient-Specific Index (intraclass correlation coefficient, 0.78).
  
  
  CONCLUSIONS
  We concluded that a self-reported version of the Patient-Specific Index, which focuses on the concerns of individuals, is reliable and has criterion validity compared with an interviewer-administered version.
authors.affiliation: Department of Surgery, University of Toronto, Ontario, Canada. jgwright@sickkids.on.ca
authors.forename: J G
authors.initials: JG
authors.lastname: Wright
authors.forename: N L
authors.initials: NL
authors.lastname: Young
authors.forename: J P
authors.initials: JP
authors.lastname: Waddell
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000534:rehabilitation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D016896:Treatment Outcome