A pilot quality-of-life instrument for pruritus - 24/04/13

Doi : 10.1016/j.jaad.2008.04.006

Nisha S. Desai, MD ^a, Gabriele B. Poindexter, MD ^b, Yvette Miller Monthrope, MD ^c, Sandra E. Bendeck, MD ^d, Robert A. Swerlick, MD ^e,^f, Suephy C. Chen, MD, MS ^e,^f,^g,^⁎
^a Washington University, Saint Louis, Missouri
^b University of North Carolina, Chapel Hill, North Carolina
^c University of Toronto, Toronto, Ontario, Canada
^d University of Texas Southwestern, Dallas, Texas
^e Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia
^f Division of Dermatology, Atlanta Veterans Administration Medical Center, Atlanta, Georgia
^g Department of Health Services Research and Development, Atlanta Veterans Administration Medical Center, Atlanta, Georgia

Reprint requests: Suephy C. Chen, MD, MS, Department of Dermatology, Emory University School of Medicine, 101 Woodruff Circle; Atlanta, GA 30322.

Abstract

Objective

We sought to develop a validated, reliable pruritus-specific quality-of-life (QOL) instrument, ItchyQoL.

Methods

From 21 in-depth interviews with patients with pruritus, we developed 22 pruritus-specific items, and hypothesized 3 major constructs that explain the way pruritus affects patients’ QOL: symptoms, functional limitations, and emotions. We developed two versions of the pruritus QOL instrument, which assess for level of bother or frequency using items from the interviews and from generic skin QOL instruments, Skindex-16 (bother) and Skindex-29 (frequency). The instrument was tested for validity, reliability, and responsiveness. The frequency version was subsequently applied clinically to further evaluate its face validity.

Results

A total of 89 patients with dermatologic conditions participated in the validation phase and 101 patients participated in the clinical application phase of the study. Construct validity was demonstrated by principal axes factor analyses and by demonstrating that differences in symptoms, functioning, and emotion differed among the varying levels of self-reported pruritus severity more than would be expected by chance (P < .05 by analysis of variance). The instrument demonstrated reliability with internal consistency (Cronbach ⍺: frequency 0.72-0.93 and bother 0.78-0.81) and reproducibility (intraclass correlation coefficient: frequency 0.91 and bother 0.84-0.87). The instrument suggested preliminary responsiveness for patients with improved disease for both frequency and bother items with both overall scores and the majority of the subscales scored demonstrating significant changes. Discriminant validity was shown by comparing differences in and the number of insensitive items between the pruritus-specific QOL instrument and the generic Skindex instruments.

Limitations

Lack of generalizability and potential selection bias are limitations.

Conclusions

This study represents, to our knowledge, the first attempt at a pruritus-specific QOL instrument that is reliable, valid, and responsive.

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Abbreviations used : ANOVA, ICC, QOL

Plan

	Supported in part from an American Skin Association (ASA) Health Services Research Grant, the ASA David Martin Carter Research Scholar Award, and an Emory Skin Disease Research Center Pilot and Feasibility grant (No. P30AR42687) from the National Institute on Arthritis and Musculoskeletal and Skin Disease (NIAMS), National Institutes of Health (NIH). Dr Chen was supported in part by a Mentored Patient Oriented Career Development Award (No. K23AR02185-01A1) from NIAMS, NIH.
	Conflicts of interest: None declared.
	Presented as abstracts at the 66th Annual Meeting of the Society for Investigative Dermatology, Miami, Florida, May 2005, and the 63rd Annual Meeting of the American Academy of Dermatology Annual Meeting, New Orleans, Louisiana, February 2005.