Table 1 A summary of the advantages and disadvantage of distribution, anchor and qualitative methods
Advantages | Disadvantages | |
|---|---|---|
Distribution method | • Distribution methods are based on statistical models [3]. • The value of 0.5 SD corresponds to the MCID across a variety of studies [4]. | • Guidelines for the interpretation of effect size are somewhat arbitrary. • This statistical approach does not consider the core concept of the MCID; the clinical importance [8]. • These methods are sample-specific; findings will vary on the sample size and distribution that the SD is based on [38]. |
Anchor method | • Anchor methods have the advantage of being more clearly understood because change scores are related to a clearly understood clinical observation [39]. • Global assessment scales are sensitive to change [40]. | • Determining the cut-off on the anchor scale is often an arbitrary decision [7]. • Global assessment scales may not always be valid. For example, they can be susceptible to recall bias [41]. |
Qualitative methods | • Gathering the views and experiences of patients provides clinical relevance to the MCID. • Qualitative data provides richer information from the participants perspective which cannot be elicited through standardized measures [8]. | • Can lack the precision needed to determine a numerical marker of MCID [8]. • Often includes smaller sample sizes, which can introduce issues with generalisability [42]. |