Single-factor scoring validation for the Health Assessment Questionnaire-Disability Index (HAQ-DI) in patients with systemic sclerosis and comparison with early rheumatoid arthritis patients

Abstract

Objective

Structural validity for the Health Assessment Questionnaire-Disability Index (HAQ-DI) has recently been provided for patients with rheumatoid arthritis (RA). The goal of the current study was to examine the structural validity of the HAQ-DI in patients with systemic sclerosis (SSc, scleroderma) and to compare its performance with that in patients with RA.

Methods

The HAQ-DI structural validity was first assessed in a sample of 100 scleroderma patients using confirmatory factor analysis. Second, the similarity of factor structures between SSc patients (n = 291) and RA patients (n = 278) was tested using a multigroup structural validity model to assure that comparison of scores between these two diagnostic groups is appropriate.

Results

Results yielded a single-factor HAQ-DI score which favored the current scoring system of the HAQ-DI (model fit was CFI = 0.99 and RMSEA = 0.04). Moreover, even the most stringent model of multigroup structural validity affirmed the similarity between SSc and RA patients on the HAQ-DI (model fit was CFI = 0.99 and RMSEA = 0.04) nor was it different from a model without any demands on group similarity: CFI difference = 0.007; χ² = 4.29, df = 26, p=0.99.

Conclusion

The current results indicate that a single-factor HAQ-DI is appropriate for future clinical trials in scleroderma and, in addition, HAQ-DI scores among patients with SSc and early RA can be compared legitimately with one another.

Appendix A

On behalf of the Scleroderma Lung Study (SLS) research group, the following investigators also participated:

University of California Los Angeles, Los Angeles, California: Philip J. Clements, MD, MPH; Donald P. Tashkin, MD; Robert Elashoff, PhD; Jonathan Goldin, MD, PhD; Michael Roth, MD; Daniel Furst, MD; Ken Bulpitt, MD; Dinesh Khanna, MD; Wen-Ling Joanie Chung, MPH; Sherrie Viasco, RN; Mildred Sterz, RN, MPH; Lovlette Woolcock; Xiaohong Yan, MS; Judy Ho, Sarinnapha Vasunilashorn; Irene da Costa.

University of Medicine & Dentistry of New Jersey, New Brunswick, New Jersey: James R. Seibold, MD*; David J. Riley, MD; Judith K. Amorosa, MD; Vivien M. Hsu, MD; Deborah A. McCloskey, BSN; Julianne E. Wilson, RN. * Current address: University of Michigan Scleroderma Program, Ann Arbor, Michigan.

University of Illinois Chicago, Chicago, Illinois: John Varga, MD; Dean Schraugnagel, MD; Andrew Wilbur, MD; David Lapota, MD; Shiva Arami, MD; Patricia Cole-Saffold, MS.

Boston University, Boston, Massachussettes: Robert Simms, MD; ArthurTheodore, MD; Peter Clarke, MD; Joseph Korn, MD; Kimberley Tobin, Melynn Nuite, BSN.

Medical University of South Carolina, Charleston, South Carolina: Richard Silver, MD; Marcie Bolster, MD; Charlie Strange, MD; Steve Schabel, MD; Edwin Smith, MD; June Arnold; Katie Caldwell; Michael Bonner.

Johns Hopkins School of Medicine, Baltimore, Maryland: Robert Wise, MD; Fred Wigley, MD; Barbara White, MD; Laura Hummers, MD; Mark Bohlman, MD; Albert Polito, MD; Gwen Leatherman, MSN; Edrick Forbes, RN; Marie Daniel.

Georgetown University, Washington, DC: zVirginia Steen, MD; Charles Read, MD; Cirrelda Cooper, MD; Sean Wheaton, MD; Anise Carey; Adriana Ortiz.

University of Texas Houston, Houston, Texas: Maureen Mayes, MD, MPH; Ed Parsley, DO; Sandra Oldham, MD; Tan Filemon, MD; Samantha Jordan, RN; Marilyn Perry.

University of California San Francisco, San Francisco, California: Kari Connolly, MD; Jeffrey Golden, MD; Paul Wolters, MD; Richard Webb, MD; John Davis, MD; Christine Antolos; Carla Maynetto.

University of Alabama, Birmingham, Alabama: Barri Fessler, MD; Mitchell,Olman, MD; Colleen Sanders, MD; Louis Heck, MD; Tina Parkhill.

University of Connecticut Health Center, Farmington, Connecticut: Naomi Rothfield, MD; Mark Metersky, MD; Richard Cobb, MD; Macha Aberles, MD; Fran Ingenito, RN; Elena Breen;

Wayne State University, Detroit, Michigan: Maureen Mayes, MD; Kamal Mubarak, MD; Jose L Granda, MD; Joseph Silva, MD; Zora Injic, RN, MS; Ronika Alexander, RN.

Virginia Mason Research Center, Seattle, Washington: Daniel Furst, MD; Steven Springmeyer, MD; Steven Kirkland, MD; Jerry Molitor, MD; Richard Hinke, MD; Amanda Mondt, RN.

University of Alabama, Birmingham: Mitchell Olman, MD; Barri Fessler, MD; Colleen Sanders, MD; Louis Heck, MD; Tina Parkhill.

On behalf of the Relaxin study, the following investigators also participated: J Korn, MD, R Simms, MD, P Merkel, MD, Boston University, Boston, MA; NF Rothfield, University of Connecticut Health Center, Farmington, CT; F Wigley, MD, Johns Hopkins University, Baltimore, MD; M Ellman, MD University of Chicago, Chicago, IL; Y Kim, MD, Stanford University, Palo Alto, CA; L Moreland, University of Alabama at Birmingham, Birmingham, AL; RW Silver, University of South Carolina, Charleston, SC; VD Steen, Division of Rheumatology, Georgetown University Medical Center, Washington, DC; M Weisman, MD, Cedar Sinai Medical Center, Los Angeles, CA; GS Firestein, MD, AF Kavanaugh, MD University of California, San Diego, CA; ME Csuka, MD Medical College of Wisconsin, Madison, WI; MD Mayes, University of Texas Health Science Center, Houston, TX; D Collier, University of Colorado, Denver, CO; TA Medsger, Jr., University of Pittsburgh, Pittsburgh, PA; and Vivian M Hsu, UMDNJ-Scleroderma Program.