Anchor- based methods aim to establish clinically meaningful changes in a continuous outcome variable by relating or anchoring them to patient-centred measures of clinical effectiveness that could be regarded as gold standards with a high level of face validity. For example, a MID for an outcome could be defined by the minimum amount of change in that outcome necessary to make patients feel their quality of life had significantly improved . MIDs in the literature may also be based on expert clinician or consensus opinion concerning the minimum amount of change in a variable deemed to affect quality of life or health. For binary variables, any MIDs reported in the literature will inevitably be based on expert consensus, as such MIDs relate to all-or-nothing population effects rather than measurable effects on an individual, and so are not amenable to patient-centred anchor methods. The GC agreed to use these published values for quality of life scores: EQ-5D 0.03 (from Sf-36 mapping),Kansas City 5 (taken from literature) and SF-36 5 (taken from literature). The GC did not support the use of other MIDs as the measures were perceived as unreliable. The GC agreed that it was appropriate to use a reduction of 10 unplanned hospitilisation per 1000 as a clinically important benefit. In the absence of values identified in the literature, the alternative approach to deciding on MID levels is the default method, as follows: For categorical outcomes the MIDs were taken to be RRs of 0.75 and 1.25. For positive outcomes such as patient satisfaction , the RR of 0.75 is taken as the line denoting the boundary between no clinically important effect and a clinically significant harm, whilst the RR of 1.25 is taken as the line denoting the boundary between no clinically important effect and a clinically significant benefit. 