The reliability and validity of the self-reported patient-specific index for total hip arthroplasty

Background: The Patient-Specific Index is unique in that it reflects how in dividual patients weigh concerns in rating the outcome of total hip arthrop lasty The Patient-Specific Index was originally administered by an intervie wer; which is not always feasible and can be costly The purposes of the pre sent study were (1) to create a self-reported version of the Patient-Specif ic Index, (2) to determine the reliability of this new self-reported versio n, and (3) to determine the relationship between the scores on the new self -reported version and those on the original interviewer-administered versio n. Methods: A self-reported version of the Patient-Specific Index was develope d, and a pilot test was performed on ten patients. Patients who were schedu led for a total hip arthroplasts or who had recently had a total hip arthro plasty were eligible for the reliability and validity testing. A copy of th e new self-reported Patient-Specific Index was mailed to the patients, and they completed it independently. The patients' ratings of the importance an d severity of twenty-four concerns prior to total hip arthroplasty,were add ed together to create a summary Patient-Specific Index score. To determine test-retest reliability, patients completed the self-reported Patient-Speci fic Index a second time, two weeks later. To determine criterion validity p articipants also completed the interviewer-administered Patient-Specific In dex. Results: Fifty-five patients completed the study The random-effects intracl ass correlation test-retest coefficient was 0.79 (greater than 0.75 represe nts excellent reliability). The mean Patient-Specific Index scores on the s elf-reported version and on the interviewer-administered version mere 173 a nd 165 points, respectively (Student t test, p = 0.45). The self-reported P atient-Specific Index was concordant with the interviewer-administered Pati ent-Specific Index (intraclass correlation coefficient, 0.78), Conclusions: We concluded that a self-reported version of the Patient-Speci fic Index, which focuses on the concerns of individuals, is reliable and ha s criterion validity compared with an interviewer-administered version.