Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
Reliability, Validity, and Minimally Important Differences of the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract (UCLA SCTC 2.0) Instrument
Khanna1, Dinesh, Hays1, Ron, Maranian2, Paul, Seibold3, James R., Impens3, Ann J., Mayes4, M., Clements5, Philip J.
UCLA, Los Angeles, CA
David Geffen School of Medicine at UCLA, Los Angeles, CA
University of Michigan, Ann Arbor, MI
U.Texas Houston, Houston, TX
UCLA School of Medicine, Los Angeles, CA
Assiut University Hospital, Assiut, Egypt
We developed a scleroderma gastrointestinal tract (SSC-GIT 1.0) instrument. The present study refines the SSC-GIT 1.0 by differentiating reflux symptoms from distention/bloating, adding a recectal incontinence scale, and creating a composite score of overall GIT burden of SSc In addition, we estimate minimally important differences of the new instrument.
We administered the SSC-GIT 1.0 and SF-36v.2 to 152 patients with SSc at 3 scleroderma centers; 1 item was added to SSC-GIT 1.0 to assess rectal incontinence. In addition, subjects completed a rating of the severity of their GIT (very mild to very severe) and physicians noted the GIT diagnosis. We evaluated internal consistency reliability, test-retest reliability (1.1 week mean time interval in 25 patients) and performed multitrait scaling analysis. 115 of the 152 patients completed the questionnaires again at Time2 (25.2 week mean time interval). Patients also completed ratings of their overall, upper, and lower GIT involvement. For example: "Compared to your last visit, how would you rate your overall/upper/lower gastrointestinal symptoms? Much better, a little better, almost the same, a little worse, or much worse." The minimally changed group was defined by those reporting they were a little better.
Study participants (n=152) were female (84%) and Caucasian (81%); 55% had diffuse SSc and mean age was 51 years. Self-rated severity of GIT ranged from no symptoms to very mild (39%), to mild (21%), to moderate (31%), to severe or very severe (9%). Of an initial 53 items in SSC-GIT 1.0, 19 had low item-total correlations (<0.40) or poor discrimination among scales and were excluded, leaving a 34-item final instrument (UCLA SCTC GIT 2.0). Analyses supported 7 multi-item scales: reflux, bloating/distention, diarrhea, soil, constipation, emotional well-being, and social well-being. Test-retest reliability estimates were >= 0.68 and coefficient alphas >=0.67. Participants who rated their GIT disease as mild had lower (better) scores on all 7 scales and those with "severe" had the higher scores on a 03 scale. In addition, symptom scales were able to discriminate subjects with corresponding clinical GIT diagnosis. The total GIT Score, developed by averaging 6 of 7 scales (excluding constipation), was reliable (test-retest 0.81 and Cronbach's alpha 0.71) provided discrimination between mild, moderate, and severe self-rated GIT involvement. MID estimates for improvement in the Total GIT score ranged from 0.160.28 (on a 03 scale; effect size estimates 0.400.52).
This study provides support for the reliability and validity of the UCLA-SCTC GIT 2.0, an improvement over the original instrument designed to assess GIT involvement in patients with SSc. An overall GIT Score was also developed to capture overall burden (severity) of SSc-associated GIT.
To cite this abstract, please use the following information:
Khanna, Dinesh, Hays, Ron, Maranian, Paul, Seibold, James R., Impens, Ann J., Mayes, M., et al; Reliability, Validity, and Minimally Important Differences of the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract (UCLA SCTC 2.0) Instrument [abstract]. Arthritis Rheum 2009;60 Suppl 10 :603