Responsiveness and interpretation of meaningful within-person change in score
Responsiveness reflects the ability of an instrument to detect changes in groups of patients who have changed in the measured concept. Change from baseline to cycles 4 and 7 for DTSS and DTIS was evaluated within groups of patients who had changed according to PGIS, using analysis of covariance (ANCOVA) and magnitude of change via effect sizes (ES) (within-group: mean change from baseline/SDMeaningful change was evaluated both at within-person level (i.e., the amount of change a person would report to indicate that a relevant benefit has been experienced) and between-group level (i.e., the difference in scores between treatment and comparator groups considered clinically meaningful). Of note, within-person thresholds can be used to define responders for statistical tests of proportions improved in each treatment group, whereas between-group thresholds support statistical inference of mean change between treatment and comparator groups and are used to assess the magnitude of the observed difference. To define meaningful change thresholds (MCTs) in DTSS and DTIS, anchor-based and distribution-based methods were evaluated and supported by visual displays of change score distribution using empirical cumulative distribution function (eCDF) curves. Firstly, the appropriateness of anchors (i.e., PGIS, PGIC) was tested by correlating them with DTSS and DTIS change scores from baseline to cycles 4 and 7; correlations > 0.30 were considered desirable [