Criterion-based validation of the EORTC QLQ-C36 in advanced melanoma: the CIPS questionnaire and proxy raters

An extensive quality of life (QOL) investigation of the effects of chemotherapy in patients with generalized malignant melanoma included a validation study of involved questionnaires. The QOL domains of the three basic quality of life questionnaires, the EORTC QLQ-C36 (European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire), a study-specific malignant melanoma (MM) module and the Hospital Anxiety and Depression (HAD) scale vs. the Cancer Inventory of Problem Situations (CIPS) were validated by correlation analyses. The value of using attending nurses and/or next of kin to assess the patients situation was also examined. Functional and symptom scales of the C36 and the subscales of the HAD showed appropriate convergent and discriminant validity when compared with the CIPS. The subscales of the MM module had less clear relationships, probably due to lack of accordance in the CIPS. Assessments of attending nurses revealed very low correlations with the patients' measures. They underestimated significantly series of specific symptoms and overestimated nausea and the overall quality of life of the patients. However, assessments of close relatives, mostly spouses, showed moderate to high correlations and no significant difference. These results further strengthen the overall validity of the modular approach of the EORTC QLQ technique. In this context of active chemotherapy in patients with advanced cancer disease, relatives seem to be better surrogates than the attending nurses in assessing the patients' quality of life.