Meaningful change in oncology quality-of-life instruments: a systematic literature review.

Quality of life (QoL) is increasingly being recognized as an important end point in oncology clinical trials. The purpose of this study was to review the literature on what constitutes a meaningful change in oncology QoL instruments. A literature search was conducted in Medline, Embase, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews. Articles determining clinically meaningful change were selected. Twenty six publications were identified. Common anchors included performance status, global rating of change and overall QoL. The distribution approach utilized standard deviations and standard error of measurement. Limitations included optimism bias and a change in patients' internal frame of reference. Currently, there is an inconsistency between meaningful change studies. Analyses should be conducted in population-specific samples, as meaningful change varies depending on patient characteristics. Consistently, meaningful change for improvement has been smaller than that for deterioration, suggesting that patients are more responsive to improvement.