Weight Module (YQOL-W)


Hong-Mei Wang, PhD1, Xiao-Ying Jiang, MSPH1, Todd Edwards, PhD2, Ying-Ping Chen, MSPH1, Donald Patrick, PhD, MSPH2

1 Institute of Social Medicine and Family Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
2 Department of Health Services, University of Washington, Seattle, WA, USA

Obesity in children and adolescents is a growing public health concern in the global world. Undergoing socioeconomic transition, China has also been besieged by an ever-expanding obesity epidemic in recent years. In 2010, the overall number for overweight and obese Chinese school-aged children (7-18 years old) has approximately reached 30.43 million, which has doubled from the 16.11 million in 2000.1 Although being overweight has been linked to multiple physical health problems in children and adolescents, including glucose intolerance and risk factors for cardiovascular disease, one of the most salient consequences of pediatric obesity may be psychosocial in nature.2,3
Subjective quality of life (QOL) is of particular interest in overweight and obese youth because psychosocial impairments are more prevalent than somatic comorbidities at younger ages. However, youth weighted- specific QOL has been little reported in China. Most studies simply translate English instruments without qualitative research and validation.4,5 Others apply adult QOL instruments or generic instruments.6,7 Lacking such a specific QOL instrument will somehow become a handicap for evaluating weight-related interventions and treatments in youth.
Youth share universal concepts of weighted-specific QOL. The Youth Quality of Life Instrument – Weight Module (YQOL-W) elicited concepts which were universal across cultures.8,9 The team of this study aimed to develop a Chinese adaptation of the YQOL-W to facilitate relevant research in China and cross-cultural comparison by linguistic validation, qualitative research, and psychometric validation of measurement properties.
Linguistic validation of the YQOL-W using forward translation, backward translation, and participant testing
The forward-backward translation progress was repeated until there were no misunderstandings, mistranslations, or inaccuracies in the forward version. A panel of 12 participants completed the comprehension test during which the interviewer inquired whether the participant had any difficulty in understanding the questionnaire and checked the participant’s interpretation of all items.
Checked conceptual equivalence and guided construction of culture specific items using inductive qualitative methods
Twenty-two in-depth, semi-structured interviews with youth ages 11–18 were conducted to explore their areas of life, goals, concerns, and worries associated with weight and weight management. Using thematic analysis to identify, categorize, and classify themes in the data, five new culture-specific items were elicited and added to the instrument. After three rounds of cognitive interviews, the Chinese version of the YQOL-W scale, including three domains (self, social, and environment) and 26 items (five items are new culture-specific items), was finalized.
The Chinese YQOL-W demonstrated acceptable measurement properties
Eight hundred and forty participants aged 11-18 years were enrolled in field testing for measurement properties. A total of 814 participants fully completed the questionnaire with the response rate of 96.90%. Measurement model, reliability, validity, and respondent burden for the Chinese YQOL-W were reported.
Three factors (23 items) were identified (self, social, and environment), with factor loading ranging from 0.42 to 1.00. The three-factor model fitted into the theoretical expectation, however, three items (item 7, 13 and 23) were eliminated, accounting for their lower factor loading (less than 0.40) and content importance.10 The latent construct of the instrument was further confirmed by confirmatory factor analysis, the goodness-of-fit indices including χ2/df, GFI, RMSEA and Standard RMR were reported, that is, 4.00, 0.90, 0.06 and 0.07, respectively, which implied that the instrument had acceptable construct validity.
Internal consistency coefficients for the self, social, and environment domains were 0.90, 0.94, and 0.84, respectively, and 0.96 for total score, demonstrating excellent internal consistency reliability. Test-retest reliability was substantially supported using the intraclass correlation coefficient (ICC) and the standard error of measurement (SEM).11 The ICCs for the self, social, and environment factors and total score were 0.709, 0.721, 0.778 and 0.778, respectively. The SEM values for the self, social, and environment factors and total score were 10.352, 9.526, 12.086 and 8.425, respectively.
Convergent and discriminant validity were demonstrated with moderate or weak correlations between comparable or less comparable scale scores of the YQOL-W and PedsQL. Significant differences were found in subscale and total scores across BMI groups and genders (P < 0.01), supporting the known-group validity of this instruments.
This study demonstrated that adolescents with different conditions were sufficiently interested to participate and complete our instrument battery, and that parents and teachers fairly supported their youth. The average completion time of the YQOL-W was five to eight minutes.
Strictly following methodology for cross-cultural instrument adaptation, our study developed the Chinese version of the YQOL-W and presented acceptable evidence of measurement properties.
This work was supported by a China Medical Board Young Faculty Seed Grant in Health Policy and Systems (HPSS).


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For more information, please contact:
Hongmei Wang, PhD,
Institute of Social Medicine and Family Medicine,
Zhejiang University School of Medicine,
866 Yuhang Tang Road, Hangzhou, 310058, Zhejiang Province, PR China – rosa@zju.edu.cn