THE -ORGANIZATION-FOR-RESEARCH-AND-TREATMENT-OF-CANCER APPROACH TO QUALITY-OF-LIFE ASSESSMENT - GUIDELINES FOR DEVELOPING QUESTIONNAIRE MODULES

The EORTC Study Group on Quality of Life (the Study Group) has adopted a modular approach to quality of life (QOL) assessment in cancer clin ical trials. A 'core' instrument-the QLQ-C30-has been designed to cove r a range of QOL issues relevant to a broad spectrum of cancer patient s. It is intended that this QLQ-C30 be supplemented by more specific s ubscales ('modules') to assess aspects of QOL of particular importance to specific subgroups of patients. Since individual members of the St udy Group were to be involved in module development, guidelines were r equired to standardize the module development process in order to ensu re uniformly high quality across modules. These guidelines are present ed in this paper. The term 'module' is defined, the composition of mod ules is outlined, and the criteria used to develop modules are specifi ed. The module development process, consisting of four phases (generat ion of relevant QOL issues, operationalization of the QOL issues into a set of items, pretesting the module questionnaire, and large-scale f ield-testing) is described in detail. Further, issues related to cross -cultural instrument development, and the need for monitoring the modu le development process from within the Study Group are discussed. Fina lly, experiences with developing two site-specific modules (i.e., for head and neck, and breast cancer), are presented and the extent to whi ch the guidelines meet practical requirements is discussed. The guidel ines appear to provide a practical tool for module construction, that can facilitate the development of a comprehensive system for assessing the QOL of cancer patients internationally.