Quality of life assessment in adolescent obesity: Development of a new instrument for ecnomic evaluation

Obesity, particularly in the younger population, is a major public health concern. Because of this, numerous public health initiatives and specialised weight management interventions are available for this population. Economic evaluations of weight management interventions can be utilised to inform resource allocation decision making. But in order to provide fully informed economic evaluations of weight management interventions, a valid and reliable tool
to a) measure weight specific quality of life (QoL) and b) assign preference values to different aspects of weight specific QoL is necessary. Currently no existing tools meet these crucial requirements, and this thesis aims to fill this gap.
The thesis utilised a multiple methodological approach in the development of a new weight specific instrument. The development of the tool comprised of four distinct studies. The first was informed by the existing literature and aimed to identify items through a) qualitative interviews with adolescents and b) discussion with specialists in the field of adolescent obesity. A long list of potential items for inclusion in the new instrument was crafted in the first study. The aim of the second study was the identification of a reduced item set by performing psychometric assessments and Rasch analysis. At the end of the first two studies the new instrument was created. The third study aimed to assess its measurement properties through
psychometric analyses. The final feasibility valuation study addressed the derivation of preference values for the states described by the instrument.
The results of the empirical studies taken together demonstrated that it is feasible to identify the impact of weight status on QoL using adolescents’ views. It has been possible to create the Weight-specific Adolescent Instrument for Economic-evaluation (WAItE), consisting of seven items each associated with five response options. It was not possible to obtain a scoring algorithm for the states described by the WAItE when three variants of discrete choice experiments were implemented. The WAItE can be used to investigate the benefits associated with alternative weight management interventions.