Responsiveness
Responsiveness demonstrates whether a questionnaire can be used to identify changes over time 5,9–11, assessing the interpretability of those changes 5,10,11. Responsiveness is supported when a measure can identify differences in results, even if these differences are small. Methods of assessing responsiveness include comparing instrument scores before and after an intervention. Specific disease measures are more sensitive to small changes in disease status and are generally considered to be more sensitive than generic measures 9. Responsiveness can be evaluated by longitudinal analyses of patients, and some used measures of responsiveness are the standardized response mean (SRM), and the effect size (ES). The SRM is calculated by dividing the mean score change by the standard deviation of the change; and the ES is the degree of change measured in standard deviations 5,12.
Responsiveness is occasionally referred to as sensitivity to change, but although they are related, they are different. Responsiveness is the ability of the instrument to measure important clinical changes among patients, whereas sensitivity to change refers to the ability of the instrument to detect any degree of change 5.