The minimum clinically important difference (MCID) for different patient reported outcomes (PROM) represent a proposed threshold value to be used in determining if a change is clinically significant. These authors point out that efforts at calculating the MCID have yielded multiple and inconsistent values. They reviewed the most recent (2014-2016) publications in leading journals to explore the limitations of its current uses, and to clarify the underpinnings of MCID calculation.
Of 1,709 clinical science articles that utilized PROMs, a MCID was referenced in 129 (7.5%).
52 (40.3%) of the129 were related to the upper extremity. 5 (9.6%) of 52 independently calculated MCID values, and 47 (90.4%) of 52 used previously published MCID values.
MCIDvalues were considered or calculated for 16 PROMs; 12 of these were specific to the upper extremity.
Six different methods were used to calculate the MCID.
Calculated MCIDs had a wide range of values for the same PROM (e.g., 8 to 36 points for Constant-Murley scores and 6.4 to 17 points for American Shoulder and Elbow Surgeons [ASES] scores).
The authors concluded that "determining useful MCID values remains elusive and is compounded by the proliferation of PROMs in the field of orthopaedics. The fundamentals of MCID calculation methods should be critically evaluated. If necessary, these methods should be corrected or abandoned."
Comment: In determining the MCID for a PROM, the investigator attempts to tie the amount of change in the PROM to some sort of an "anchor" global assessment: i.e. "improved" or not, "better" or not, "satisfied" or not. The problems with these types of "anchor" is that they are imprecise and poorly defined. Does "improved" mean that there is an overall improvement in the condition from 6 months ago, 1 year ago or 2 years ago. If the latter, how reliably can the patient recall the shoulder's condition 2 years ago? How much of an improvement is required to establish the anchor? Does "satisfied" mean that the condition of the shoulder is different or that the care was satisfactory? As the authors state, "Unfortunately, there is no consensus agreement on what anchor or even specific anchor level (or levels)would best express a minimum important change." Beyond these issues with the anchor, there are important differences in the way data are analyzed to determine the MCID.
Furthermore, a specific MCID needs to be determined for each PROM and for each diagnosis and for each treatment. What should we do if different authors report different values for the MCIDs for a given PROM (see above examples for Constant and ASES when the values vary by >400%).
The concept of the MCID implies that - if we take 17 points on the ASES score as being the MCID - the improvement from an ASES score from zero to 17 has the same significance as the improvement from 80 to 97. It seems doubtful that the patient would see it that way.
Perhaps even more importantly is that the concept of the MCID is difficult to communicate to our primary customers: our patients. How exactly would you talk about the expected outcome of a procedure in terms of the MCID?
In our experience, the percent of maximal possible improvement addresses may of the shortcomings of the MCID. The %MPI is easily determined as the preoperative to postoperative change in the PROM divided by the difference between a "perfect" score on the PROM and the preoperative score.
The advantages of this approach are:
It does not require that the patient try to recall the pretreatment condition of the shoulder.
It does not require patients to answer an anchor question, such as "are you improved?"
It does not create a somewhat arbitrary dividing line between a good result and otherwise: is a chance in ASES score of 16 really different than an ASES score of 18?
It does not require a choice of among different methods of calculations to derive the value.
And, importantly, it the percent of maximal possible improvement is easy to explain to the patient.
The interested reader may like to visit these posts for additional examples and explanations:
How much improvement in the SST, ASES, and VAS score is clinically significant?
=====
We have a new set of shoulder youtubes about the shoulder, check them out at this link.
Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link
Use the "Search" box to the right to find other topics of interest to you.
You may be interested in some of our most visited web pages arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'
