The overall purpose of this study was to develop and evaluate the reliability and validity of the IWQOL-Kids, a 27-item measure of weight-related quality of life for adolescents (ages 11 to 19). These preliminary analyses provide support for the measure’s strong psychometric properties, discrimination among BMI groups and between clinical and community samples, and responsiveness to a weight loss/social support intervention. Four factors, accounting for 71% of the variance, were identified, including physical comfort, body esteem, social life, and family relations.
The items on the physical comfort scale assess one’s perception of how weight impacts mobility and comfort in everyday life (e.g., difficulties fitting into seats, bending over, climbing stairs, or crossing legs). These physical discomforts are known to be significant issues for obese adults (42
); however, to our knowledge, there are no studies documenting the impact of these physical discomforts in obese youth. Although existing generic measures of HRQOL assess one’s general ability to run or play sports (9
) or strength and endurance (48
), the IWQOL-Kids physical comfort scale specifically addresses bodily comfort associated with an individual’s weight status.
The body esteem scale assesses the impact of weight on body self-perceptions and appearance. This domain finds empirical support from the broader pediatric obesity literature in that data have shown consistently that obesity in youth is associated with poor body-esteem or body image (49
) and poor self-concept (50
). As expected, female (52
) and white, Non-Hispanic (54
) adolescents reported greater impairment in body esteem when compared with males and African-American youth, respectively. Given its novelty and demonstrated sensitivity, this domain, which is not assessed on existing generic HRQOL measures, may prove important to intervention research focusing on weight change.
Although social functioning is often assessed in both pediatric and adult measures of HRQOL, the social life scale of the IWQOL-Kids asks adolescents to examine their social relations within the context of their weight status. It is known that obese adolescents are more socially isolated than their non-overweight peers (55
) and have fewer friendships (56
). Obese youth report more victimization by peers (57
) and are subject to more stigmatization (e.g., name-calling, teasing) (58
). The IWQOL-Kids social life domain captures the adolescents’ perceptions of their peer group experience and confirms what has often been reported stereotypically for obese youth.
The assessment of pediatric HRQOL must be considered within the family context; accordingly, the family relations scale provides a window into how the adolescent perceives family members’ interactions with them as a result of their weight. The present data suggest that the family relations of obese youth are characterized by stigmatization, exclusion, and shame. To date, the literature on the family correlates of pediatric obesity is lacking (62
), although there are published data describing weight-related teasing by family members (61
) and low family connectedness (63
) within families of overweight youth. Although there are established generic HRQOL measures that assess the impact of pediatric chronic health conditions on parent and family functioning [e.g., Child Health Questionnaire (8
), PedsQL Family Impact Module (64
)], the IWQOL-Kids family relations scale uniquely assesses how weight impacts family relations.
In the past, researchers utilized adult instruments to measure HRQOL in the adolescent population (e.g., 65
). However, given the developmental and contextual differences in the daily lives of children and adolescents, there has been a significant push in the past decade for the development of youth-specific HRQOL measures. The literature suggests that pediatric measures should contain items that correspond to the experiences, activities, and contexts that are directly relevant to the age of the sample (66
). Although some content areas assessed by the IWQOL-Kids are similar to those on its adult counterpart (i.e., IWQOL-Lite), there are notable differences between these two measures due to developmental issues relating to youth. For example, several items on the IWQOL-Kids focus on the school and peer environments because they are particularly salient for adolescents. As a result, the IWQOL-Kids is a developmentally appropriate, weight-specific measure that should be utilized for adolescents between the ages of 11 and 19.
Because generic and condition-specific measures of HRQOL each offer unique advantages, studies may benefit from including both types of measures (11
). Evaluation with generic measures is useful for comparing HRQOL across different diseases. For example, obese children and adolescents report their generic quality of life to be similar to that of pediatric cancer patients receiving chemotherapy (39
). On the other hand, use of condition-specific measures has several advantages, one of which is greater sensitivity, which was observed in the current study when comparing the IWQOL-Kids and the PedsQL.
Quality of life concerns are important to address for a number of reasons. Assessing quality of life may help clinicians and researchers to understand the burden of a specific disease, establish the comparative efficacy of different treatments, and directly treat concerns that are important to patients (67
). Increasingly, clinical trials include quality of life assessments in addition to standard medical endpoints (66
). Although the goal of some treatments may be to improve quality of life, an alternate goal may be to ensure that quality of life does not deteriorate when a new treatment designed to improve health is administered (69
). Because weight loss may be difficult to achieve, many youth may experience obesity as a chronic condition. Directly improving their quality of life even in the absence of weight loss may be a desirable goal.
There are several notable strengths of this study, including sample size, geographic and ethnic diversity, range of z
-BMI, and the inclusion of both clinical and community samples. This allows for greater generalization to adolescent youth of all weight ranges. Nevertheless, some limitations of the present study must be noted. First, psychome-tricians have long recognized that instrument validation is a multistep, iterative process (71
). The present paper is a preliminary step in this process. Critical psychometric measurement issues, such as test-retest reliability and confirmatory factor analysis, will be addressed in future studies. Second, similarly to well-established generic measures [e.g., PedsQL (9
), Child Health Questionnaire (8
), and Short Form-36 (72
)], the IWQOL-Kids demonstrates ceiling effects, especially in adolescents within the normal-weight range. These ceiling effects were anticipated for this particular group given that weight does not influence their daily functioning in the same way as it does obese adolescents.
Future studies should also evaluate the impact of moderating variables that have proven important to understanding weight-related HRQOL in adults, such as the presence of comorbid medical conditions (73
), non-obesity-related chronic illnesses (30
), pain (74–76
), binge eating (26
), and depression (75
). Clearly, further exploration of demographic variations by gender (24
), age (41
), and ethnicity (24
) will be important. Other areas for future research include the development of a weight-related measure for use in younger children and a parent-proxy form, with subsequent further evaluation of convergence between youth and parent reports of weight-related quality of life.
Given the growing prevalence and extent of obesity in youth, the development of a reliable and valid measure that assesses the impact of weight on quality of life in this age group is timely. Because the IWQOL-Kids is self-administered and brief (taking ~8 minutes to complete), it poses minimal respondent burden. Given these preliminary data documenting its strong psychometric properties, the IWQOL-Kids is likely to be a valuable tool for both obesity clinicians and researchers.