Two recent studies funded in part by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) have examined questionnaires for those who seek to quantify the effect of skin disease on the physical, psychological and social functioning of patients and their families. Both studies indicate that it may be possible to develop questionnaires that are shorter, but equally valid statistically as those used today.
One of the NIAMS-funded studies involved the Skindex-29, a well-studied, dermatology-specific, health-related quality-of-life questionnaire for patients that was developed several years ago with NIAMS support. Mary-Margaret Chren, M.D., of the University of California at San Francisco, who originally developed the Skindex-29, worked with colleagues in Rome and Rotterdam to examine the performance of Skindex using a cutting-edge psychometric strategy called Item Response Theory. With this strategy, both the central hypothesis of a model and the quality of the estimates it provides can be measured.
Using a statistical tool called the Rasch model, the investigators found that a subset of the 29 questions in the Skindex-29 may perform statistically as well as the larger number, raising the question of whether similar information about the burden experienced by patients can be measured in an easier way. However, they point out that shorter questionnaires must be tested formally in other populations before they can be widely adopted.
In a commentary published last year in the Journal of Investigative Dermatology, dermatologist Sue Lewis-Jones described studies about health-related quality of life as "an attempt to provide standardized quantitative data and a more meaningful and structured approach to patient care." A compromise must be struck between scales that include many items and can capture maximum data in a research setting, and scales that include fewer items providing less data, which can be used more easily in a clinical setting, Lewis-Jones noted. 1
In a second study, Dr. Chren worked with Dr. Sarah Chamlin from Northwestern University and other colleagues in Chicago and San Francisco to develop a 62-item health-related quality-of-life questionnaire for parents of young children with atopic dermatitis. Atopic dermatitis is a prevalent, chronic condition of childhood. Because it is difficult for researchers and clinicians to collect data from small children, the investigators developed the Childhood Atopic Dermatitis Impact Scale to measure a parent's assessments of his or her child's condition. Parents are asked about how the child's condition affects the child in terms of symptoms, activity limitation and behavior. They are also asked how the child's condition affects the parents in terms of family and social function, sleep and emotions. Of the 62 items on the original questionnaire, 17 were eliminated, yielding a 45-item scale that appears to have substantial evidence of validity, and promise for clinical research.
The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, a part of the Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.
1Lewis-Jones S. Measuring the burden of atopic eczema in young children and the family unit. J Invest Dermatol. 2005;125(6):viii.
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Chamlin S, et al. Development of the Childhood Atopic Dermatitis Impact Scale: initial validation of a quality-of-life measure for young children with atopic dermatitis and their families. J Invest Dermatol. 2005;125(6):1106-11.
Nijsten T, et al. Testing and reducing Skindex-29 using Rasch analysis: Skindex-17. J Invest Dermatol. 2006;126(6):1244-50.