Bulletin
of the Multinational Center
of Quality of Life Research № 3-4

Gulbrandsen¹, Marianne J. Hjermstad² и Finn Wisloff1 for the Nordic Myeloma Study Group

Interpretation of quality of life scores in multiple myeloma by comparison with a reference population and assessment of the clinical importance of score differences

¹ DEPARTMENT OF HAEMATOLOGY, ULLEVAL UNIVERSITY HOSPITAL, NORWAY
² DEPARTMENT OF BEHAVIORAL SCIENCES IN MEDICINE, UNIVERSITY OF OSLO, NORWAY

Objectives: without clear guidelines, clinicians and health care providers are often uncertain how to interpret quality of life (QOL) scores.
To facilitate the interpretation, QOL scores of multiple myeloma patients at diagnosis were compared with the scores of a reference population, and the clinical significance of QOL score differences and of changes in scores over time was assessed.
Methods: data from two prospective Nordic Myeloma Stydy Group trials (221 patients<60 yr treated with high dose chemotherapy, and 203patients >60 yr treated with melphalan and prednison) were analysed. The EORTC QLQ-C30 questionnaire was used. The results were compared with the scores of an age- and gender- adjusted Norwegian reference population (n=3000), using a regressional approach. The magnitude of the observed differences and of score changes during follow-up was estimated as effect sixe [score difference (SD)] and according to a subjective rating system as a small, moderate or large.
Results: At diagnosis, the most distressing problems were pain and fatigue, reduced physical functioning, limitations in role functioning and reduced overall QOL. These differences from the refderence population were statistically significant (p < 0.001), and large or moderate improvement in mean QOL scores were observed for most domains.
Conclision: Comparison with a reference population eases the interpretation of QOLscores and prevents overestimation of symptoms and underestimation of subjective treatment response. The agreement between the two methods to evaluate the meaning of differences and changes in QOL scores was good.