Responsiveness (also known as ‘sensitivity to change’) concerns the instrument’s ability to distinguish clinically important changes because of an intervention. For an instrument to be responsive it must have the capacity to detect small but clinically significant changes over time. A responsive instrument will demonstrate scores that increase if the patient improves, decrease if the patient worsens or will not change if the patient’s state remains stable. The opposite may be true depending on the scoring system used. For instance, a higher score on the PHQ-9 reflects more severe disease. Responsiveness is particularly relevant for disease-specific measures. The most common methods of estimating an instrument’s responsiveness include: (1) Effect size = (M2 – M1) / SD1 where M1 = Mean at T1, M2 = Mean at T2 and SD1 = Standard deviation at T1. The effect size (d) relates change over time to the standard deviation of baseline scores (and, as a result, is largely dependent on the variability of scores at baseline).d is defined in terms of magnitude of change (small = 0.2; moderate = 0.5; large = 0.8).(2) Standardised response mean (SRM) = (M2 – M1) / SDdiff where SDdiff = Standard deviation of score changes.
How to cite: Responsiveness [online]. (2016). York; York Health Economics Consortium; 2016. https://yhec.co.uk/glossary/responsiveness/