A clinical model for quality of life assessment in cancer patients receiving chemotherapy.

BACKGROUND: The pattern of symptoms experienced by cancer patients during chemotherapy is very complex. Consequently, quality of life (QOL) assessment has to be carefully planned to capture clinically relevant changes. PATIENTS AND METHODS: A clinical model of changes in symptoms experienced by symptomatic metastatic patients during several courses of chemotherapy has been developed. The model differentiates cancer-related symptoms, acute side-effects, chronic side-effects and symptoms not related to cancer. The model was used to predict changes in each of these four symptom groups. Three time points were selected (post-cycle 2, pre-cycle 3, post-cycle 5) and an appropriate window around each time point was set. The model predictions were tested empirically with 56 patients with advanced ovarian cancer who completed the EORTC QLQ-C30 plus disease specific items during a six-cycle course of chemotherapy. RESULTS: The changes observed in the sample were in accordance with the changes predicted by the clinical model. Results from patients who did not complete the questionnaire within the specified time windows tended to dilute the findings from the group who did. CONCLUSIONS: A clinical model is useful in the planning of QOL assessments in order to capture clinically relevant effects. Such models also facilitate the interpretation of QOL studies, particularly when cyclic short-term effects and chronic side-effects are overlaid on disease symptoms, as is the case with chemotherapy for cancer