Identifying meaningful intra-individual change standards for health-related quality of life measures

Although numerous measures have been developed for the evaluation of health -related quality of life (HRQoL), strategies for identifying meaningful int ra-individual change in these measures have not kept pace with instrument d evelopment. As a result, clinical trial researchers, quality assurance asse ssment teams and practising clinicians are without established standards to evaluate individual patient change in HRQoL measures as improved, stable o r declined, This article reviews and critiques the methods that have been a pplied to establish intra-individual HRQoL change standards. These methods include within-person and between-persons anchor-based studies, as well as distribution-based techniques using the effect size, the standard error of measurement, the mean squared error or individual slope coefficients derive d from hierarchical linear modelling. Practical approaches to improving and advancing HRQoL change evaluations that enhance the interpretation of intr a-individual change are provided. Two future methodological challenges in t his area of HRQoL research are examined: (1) the development of individual change standards for generic HRQoL measures; and (2) the incorporation of i ndividual clinical assessments into the process for establishing significan t intra-individual change standards.