ISYQOL performs better than SRS22
An Isico study entitled The Italian Spine Youth Quality of Life questionnaire measures health-related quality of life of adolescents with spinal deformities better than the reference standard, the Scoliosis Research Society 22 questionnaire, by Antonio Caronni, Sabrina Donzelli, Fabio Zaina and Stefano Negrini, was recently published in Clinical Rehabilitation.
The aim of this cross-sectional study was to compare the validity of the Italian Spine Youth Quality of Life questionnaire (ISYQOL) with that of the Scoliosis Research Society 22 (SRS22) questionnaire, the criterion standard instrument for health-related quality of life (HRQOL) measurement in adolescents with spinal deformities.
The Scoliosis Research Society–22 questionnaire (SRS22) is the most common measure of quality of life in scoliosis patients. It is a five-domain questionnaire developed according to the classical test theory and, in this framework, it showed satisfactory psychometric properties such as concurrent validity and reliability. SRS22 is the criterion standard instrument for measuring quality of life in adolescent idiopathic scoliosis and it is also widely used for measuring quality of life in hyperkyphosis.
“We considered 742 idiopathic scoliosis patients aged between 10 and 18 years of age, 542 of whom were brace wearers”, explains Dr Fabio Zaina, one of the authors of the study. “The ISYQOL is the first instrument developed by using the Rasch analysis to measure quality of life in spine deformity patients during growth. ISYQOL is a quality of life measure that fully complies with requirements of a fundamental measure”
ISYQOL consists of 20 items, each assigned a score of 0, 1 or 2. By means of Rasch analysis, the ordinal ISYQOL total score is converted to an interval measure (i.e. ISYQOL measure), which is expressed on a scale of 0%–100% (with 100% indicating great quality of life). Seven ISYQOL items assess the impact of bracing on quality of life and are to be administered only to people wearing a brace. Thanks to the Rasch analysis, it is possible to compare the ISYQOL score of people not wearing a brace (who answer only 13 of the 20 items) with the ISYQOL score of those wearing a brace (who complete the full questionnaire). The Spearman’s correlation coefficient (rho) between ISYQOL and SRS22 was used to assess ISYQOL concurrent validity. Sex, age, severity, bracing, trunk appearance and deformity type were assessed for known-groups validity.
“The concurrent validity analysis showed the high validity of the ISYQOL measure with respect to the criterion standard measure of quality of life” concludes Dr Zaina. “Moreover, ISYQOL performs better than SRS22, having better known-groups validity and (contrary to SRS22) detecting the impact of disease severity on HRQOL.”