Published in:
01-09-2012 | Original Article
Head-to-head comparisons of quality of life instruments for young adult survivors of childhood cancer
Authors:
I-Chan Huang, Gwendolyn P. Quinn, Kevin Krull, Katie Z. Eddleton, Devin C. Murphy, Elizabeth A. Shenkman, Patricia D. Shearer
Published in:
Supportive Care in Cancer
|
Issue 9/2012
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Abstract
Purpose
Few studies examine the relevance of health-related quality of life (HRQOL) instruments for young adult survivors of childhood cancer (YASCC). This study compared the psychometric properties of two survivor-specific instruments, the Quality of Life–Cancer Survivor (QOL-CS) and Quality of Life in Adult Cancer Survivor (QLACS).
Methods
Data from 151 YASCC who enrolled in cancer/tumor registries of two medical centers were used. We examined construct validity by conducting confirmatory factor analysis using indices of chi-square statistic, comparative fit index, and root mean square error of approximation. We examined convergent/discriminant validity by comparing Pearson’s correlation coefficients of homogeneous (e.g., physical functioning and pain) of both instruments versus heterogeneous domains (e.g., physical and psychological functioning). We assessed known-groups validity by examining the extent to which HRQOL differed by late effects and comorbid conditions and calculated relative validity (RV) defined as contrasting F-statistics of individual domains to the domain with the lowest F-statistic. Superior known-groups validity is observed if a domain of one instrument demonstrates a higher RV than other domains of the instruments.
Results
YASCC data cannot replicate the constructs both instruments intend to measure, suggesting poor construct validity. Correlations of between-homogeneous and between-heterogeneous domains of both instruments were not discernible, suggesting poor convergent/discriminant validity. Both instruments were equally able to differentiate HRQOL between YASCC with and without late effects and comorbid conditions, suggesting similar known-groups validity.
Conclusions
Neither instrument is superior. Item response theory is suggested to select high-quality items from different instruments to improve HRQOL measure for YASCC.