Patterns over time in quality of life, coping and psychological adjustmentin late stage melanoma patients: An application of multilevel models

Background: Quality of life (QOL) assessment is an important component with in cancer research. There is often variability in QOL scores both between p atients and across time. Understanding this variability in terms of persona l characteristics and psychosocial factors would be useful but is often obs tructed by the types of analyses that are applied to longitudinal data sets . Improved understanding can be gained with the application of multi-level or hierarchical models that allow for greater flexibility for modelling ind ividual patterns of change over time. Methods and patients: Questionnaires were sent to a cohort of stage IV melanoma patients seen at the Sydney Mela noma Unit between 1991 and 1996, approximately every 3 months for up to 2 y ears. The data reported here are from a sub-sample of 44 patients who each completed between 3 and 8 questionnaires. Three aspects of QOL were measure d (effort to cope, mood and physical well-being), each with a single LASA l ine. Multilevel techniques were used to model the patterns of QOL over time . Covariates were added to explain variation between patients in their aver age QOL and change in QOL over time. Results: The scores of each of the thr ee QOL measures showed marked fluctuations over time. However, there was li ttle systematic change during the study in either effort to cope (p = 0.32) or mood (p = 0.06). In contrast, the physical well-being scores of some pa tients improved while others deteriorated (p < 0.001). On average, physical well-being deteriorated (p < 0.001). Variability between patients accounte d for 60% (effort to cope), 45% (mood) and 44% (physical well-being) of the total variance of each scale. A range of psycho-social factors including a ctive and avoidant coping styles and psychological adjustment accounted for significant amounts of the variability between patients in each QOL measur e. Conclusion: Individual coping and psychological adjustment are related t o individual changes in QOL and to differences among patients' QOL. The stu dy illustrates the use of multi-level techniques to further our understandi ng of differences between patients in their QOL and how it changes over tim e.