The Minimal Clinically Important Difference Changes Greatly Based on the Different Calculation Methods

Abstract

Background: The minimal clinically important difference (MCID) for patient-reported outcome measures (PROMs) expresses both the extent of the improvement and the value that patients place on it. MCID use is becoming increasingly widespread to understand the clinical efficacy of a given treatment, define guidelines for clinical practice, and properly interpret trial results. However, there is still large heterogeneity in the different calculation methods. Purpose: To calculate and compare the MCID threshold values of a PROM by applying various methods and analyzing their effect on the study results interpretation. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: The data set used to investigate the different MCID calculation approaches was based on a database of 312 patients affected by knee osteoarthritis and treated with intra-articular platelet-rich plasma. MCID values were calculated on the International Knee Documentation Committee (IKDC) subjective score at 6 months using 2 approaches: 9 methodologies referred to an anchor-based approach and 8 methodologies to a distribution-based approach. The obtained threshold values were applied to the same series of patients to understand the effect of using different MCID methods in evaluating patient response to treatment. Results: The different methods employed led to MCID values ranging from 1.8 to 25.9 points. The anchor-based methods ranged from 6.3 to 25.9, while the distribution-based ones were from 1.8 to 13.8 points, showing a 4.1× variation of the MCID values within the anchor-based methods and a 7.6× variation within the distribution-based methods. The percentage of patients who reached the MCID for the IKDC subjective score changed based on the specific calculation method used. Among the anchor-based methods, this value varied from 24.0% to 66.0%, while among the distribution-based methods, the percentage of patients reaching the MCID varied from 44.6% to 75.9%. Conclusion: This study proved that different MCID calculation methods lead to highly heterogeneous values, which significantly affect the percentage of patients achieving the MCID in a given population. The wide-ranging thresholds obtained with the different methodologies make it difficult to evaluate the real effectiveness of a given treatment questioning the usefulness of MCID, as currently available, in the clinical research.

The Minimal Clinically Important Difference: Response

“…We overwhelmingly agree with this point—and feel it warrants further discussion. The MCID is an imperfect solution to a complicated problem, and we feel this is highlighted by our work and that of Franceschini et al 2 We do, however, disagree with Dr. Tenan on the conclusion of the Food and Drug Administration (FDA) regarding the best use of MCID in clinical research.…”

Responsiveness and Minimal Clinically Important Difference of the Thai Version of the International Knee Documentation Committee Subjective Knee Form in Patients With Anterior Cruciate Ligament Injury

“…5 Various analytic methods have been used to calculate the MCID, which can be categorized as anchor-based or distribution-based. 9,18,20 In the present study, an anchor-based approach was applied. Using the Youden index, the MCID of the Thai IKDC-SKF in patients undergoing primary ACLR was 15.5.…”

The Minimal Clinically Important Difference: Letter to the Editor

“…We recently read the Journal ’s 2 published papers on minimal clinically important difference (MCID) metrics. 1,5 In particular, we appreciate the conclusion reached by Franceschini et al 5 that MCIDs, in their current form, have no utility in clinical research. While we applaud the contributions by Bloom et al 1 to the scholarly discourse, we feel the need to provide some clarification regarding the position of the Food and Drug Administration (FDA) on the topic of MCIDs.…”

“…While there are many valid criticisms that can be made about different types of MCIDs (some of which are addressed by Franceschini et al 5 and Bloom et al 1 ), the flaw is really in the desire for a simple threshold. MCIDs are not thresholds, and mounting evidence demonstrates they are not simple.…”