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Ann Rheum Dis. 2015 Jan;74(1):104-7. doi: 10.1136/annrheumdis-2013-204053. Epub 2013 Oct 4.

Responsiveness and minimally important difference for the patient-reported outcomes measurement information system (PROMIS) 20-item physical functioning short form in a prospective observational study of rheumatoid arthritis.

Author information

1
Department of Medicine, UCLA Division of General Internal Medicine & Health Services Research, Los Angeles, California, USA RAND, Santa Monica, California, USA.
2
Department of Medicine, UCLA Division of General Internal Medicine & Health Services Research, Los Angeles, California, USA.
3
Stanford ARAMIS Program, Stanford University School of Medicine, Palo Alto, California, USA.

Abstract

OBJECTIVE:

To estimate responsiveness (sensitivity to change) and minimally important difference (MID) for the Patient-Reported Outcomes Measurement Information System (PROMIS) 20-item physical functioning scale (PROMIS PF-20).

METHODS:

The PROMIS PF-20, short form 36 (SF-36) physical functioning scale, and Health Assessment Questionnaire (HAQ) were administered at baseline, and 6 and 12 months later to a sample of 451 persons with rheumatoid arthritis. A retrospective change (anchor) item was administered at the 12-month follow-up. We estimated responsiveness between 12 months and baseline, and between 12 months and 6 months using one-way analysis of variance F-statistics. We estimated the MID for the PROMIS PF-20 using prospective change for people reporting getting 'a little better' or 'a little worse' on the anchor item.

RESULTS:

F-statistics for prospective change on the PROMIS PF-20, SF-36 and HAQ by the anchor item over 12 and 6 months (in parentheses) were 16.64 (14.98), 12.20 (7.92) and 10.36 (12.90), respectively. The MID for the PROMIS PF-20 was 2 points (about 0.20 of an SD).

CONCLUSIONS:

The PROMIS PF-20 is more responsive than two widely used ('legacy') measures. The MID is a small effect size. The measure can be useful for assessing physical functioning in clinical trials and observational studies.

KEYWORDS:

Health Services Research; Outcomes Research; Rheumatoid Arthritis

PMID:
24095937
PMCID:
PMC3976454
DOI:
10.1136/annrheumdis-2013-204053
[Indexed for MEDLINE]
Free PMC Article

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