Background
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]. |
Methods
The SF-36-PFS
Anchor method and distribution methods
Participants
Analyses
Qualitative methods
Qualitative interviews procedure
Results
Quantitative results
Distribution method
Anchor method
Clinical Global Impression at 6 months’ follow-up | SF-36-PFS change between baseline and 6-months’ follow-up | |||
---|---|---|---|---|
Median (IQR) | Mean (95% CI) | SD | n | |
Very much better | 30 (20, 40) | 33.1 (25.1, 41.0) | 19.3 | 25 |
Much better | 20 (5, 35) | 20.1 (14.8, 25.5) | 22.3 | 69 |
A little better | 10 (−5, 20) | 8.8 (3.9, 13.7) | 20.1 | 67 |
No change | 0 (−12, 15) | −0.9 (−11.9, 10.1) | 18.2 | 13 |
A little worse | 7 (−10, 10) | 3.8 (−9.9, 17.6) | 22.7 | 13 |
Much worse | −15 (−20, 5) | −6.8 (− 20.5, 6.9) | 17.8 | 9 |
Very much worse | −25 (−40, −10) | −25.0 (− 215.6, 165.6) | 21.2 | 2 |
Qualitative results
“Cause it’s small things”
“Yeah, I’ve got, erm, my bedroom upstairs and my brother’s bedroom is up-upstairs… So you’ve got to go up those stairs” (Child).
“If like the climbing several flights of stairs went not limited at all, would be a good, quite small change” (Child)
“So you can help around the house and, and do things with people.” (Child).
“Being able to lift and carry stuff, and not ache afterwards.” (Child).
Accepting some level of limitation (in vigorous activity and walking long distances)
“That’s it really, I mean I’m happy to just sort of get on with it if it’s a little bit limited, I can just deal with it” (Child).
“‘Cause, I mean, you don’t have to run, that’s not really a big thing.” (Child).
Limitation of the SF-36-PFS and the MCID interview
“But yeah I think some of the things on here I’ve never really had a problem with doing anyway, like bathing, undressing myself never really has been a problem. Bending or stopping like there’s never really been a problem with that, like I’ve aches and pains but it’s never stopped me from doing any of those, so yeah.” (Child).
“…it’s so variable day to day that you can’t pigeonhole it in those little things like, do you know what I mean? I don’t know if that’s the answer you want, but that is the answer I feel is right…” (Parent).