Reliability and validity of the Wolfram Unified Rating Scale (WURS)
1 Program in Occupational Therapy, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
2 Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110, USA
3 Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
4 Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
5 Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
6 Departments of Neurology, Pediatrics & Biomedical Genetics, Center for Neural Development & Disease, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, 14642, USA
Orphanet Journal of Rare Diseases 2012, 7:89 doi:10.1186/1750-1172-7-89Published: 14 November 2012
Wolfram syndrome (WFS) is a rare, neurodegenerative disease that typically presents with childhood onset insulin dependent diabetes mellitus, followed by optic atrophy, diabetes insipidus, deafness, and neurological and psychiatric dysfunction. There is no cure for the disease, but recent advances in research have improved understanding of the disease course. Measuring disease severity and progression with reliable and validated tools is a prerequisite for clinical trials of any new intervention for neurodegenerative conditions. To this end, we developed the Wolfram Unified Rating Scale (WURS) to measure the severity and individual variability of WFS symptoms. The aim of this study is to develop and test the reliability and validity of the Wolfram Unified Rating Scale (WURS).
A rating scale of disease severity in WFS was developed by modifying a standardized assessment for another neurodegenerative condition (Batten disease). WFS experts scored the representativeness of WURS items for the disease. The WURS was administered to 13 individuals with WFS (6-25 years of age). Motor, balance, mood and quality of life were also evaluated with standard instruments. Inter-rater reliability, internal consistency reliability, concurrent, predictive and content validity of the WURS were calculated.
The WURS had high inter-rater reliability (ICCs>.93), moderate to high internal consistency reliability (Cronbach’s α = 0.78-0.91) and demonstrated good concurrent and predictive validity. There were significant correlations between the WURS Physical Assessment and motor and balance tests (rs>.67, p<.03), between the WURS Behavioral Scale and reports of mood and behavior (rs>.76, p<.04) and between WURS Total scores and quality of life (rs=-.86, p=.001). The WURS demonstrated acceptable content validity (Scale-Content Validity Index=0.83).
These preliminary findings demonstrate that the WURS has acceptable reliability and validity and captures individual differences in disease severity in children and young adults with WFS.