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Minimally Clinically Important Difference (MCID) Is a Low Bar

      Abstract

      Patients don't care about “statistical” significance. Patient-centered outcome measures focus on “clinical” significance and include minimal clinically important difference (MCID), patient acceptable symptomatic state (PASS), substantial clinical benefit (SCB), and maximal outcome improvement (MOI). “Minimal” is a low bar. MCID neither addresses whether patients are satisfied nor whether they have derived a substantial benefit. MCID is commonly reported allowing comparison between studies, and MCID can be calculated retrospectively, so reporting MCID is acceptable. However, we also need to report PASS, SCB, and, in unique patients like high-level athletes, we may also need to report MOI to adjust for high pretreatment scores and a ceiling effect. Finally, threshold scores are patient-level metrics and must be reported as percentage of patients who meet the threshold, not reported as to whether, as a group, the mean score for the cohort meets the threshold or not (which is a common error).
      Imagine you’re a patient. Imagine you’re recovering from injury or illness, with or without surgical intervention. After rehabilitation and recovery, think back on how you felt at your worst compared with how you feel now. Consider how your condition has changed.
      Finally, imagine you are given a choice. Your improvement can either be a
      • minimal clinically important difference (MCID);
      • patient acceptable symptomatic state (PASS);
      • substantial clinical benefit (SCB); or
      • maximal outcome improvement (MOI).
      Which would you choose? Of one thing we are certain—it would not be the “minimal” amount of improvement.
      The definition of MCID is “(t)he smallest difference in score in the domain of interest which patients perceive as beneficial and which would mandate, in the absence of troublesome side effects and excessive cost, a change in the patient’s management.”
      • Cook C.E.
      Clinimetrics corner: The minimal clinically important change score (MCID): A necessary pretense.
      “The term MCID was first described…(because) statistically significant changes often… had little clinical significance.”
      • Cook C.E.
      Clinimetrics corner: The minimal clinically important change score (MCID): A necessary pretense.
      Statistically significant changes may have little clinical significance. It’s a very good point. While a P value helps authors prove statistical significance, patients don’t care about their P values.
      • Lubowitz J.H.
      • Brand J.C.
      • Rossi M.J.
      Our measure of medical research should be appreciable benefit to the patient.
      As we’ve clearly asserted, clinical significance is more important than statistical significance.
      • Lubowitz J.H.
      • Brand J.C.
      • Rossi M.J.
      Our measure of medical research should be appreciable benefit to the patient.
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Faucett S.C.
      • Dhawan A.
      Research pearls: The significance of statistics and perils of pooling. Part 1: Clinical versus statistical significance.
      • Lubowitz J.H.
      • Cote M.P.
      • Brand J.C.
      • Rossi M.J.
      Authors dichotomize medical research findings as significant versus not significant, creating a false sense of certainty, and report outcomes on patients whose results have been previously reported without proper disclosure.
      • Cote M.P.
      • Lubowitz J.H.
      • Brand J.C.
      • Rossi M.J.
      Misinterpretation of P values and statistical power creates a false sense of certainty: Statistical significance, lack of significance, and the uncertainty challenge.
      Patients want to feel better. Patients want to return to their activities. Clinical significance is what matters. And, a minimal difference is too low a bar.
      Yet, to be fair, let’s take a step back and examine why we even report a minimal difference. For one thing, MCID came first. To our knowledge, MCID was first presented at the AANA Annual Meeting, as abstracted in Arthroscopy, in 2010.
      • Phillips L.
      • Mohtadi N.
      • Chan D.
      The responsiveness and minimal clinically important difference (MCID) of the Mahorn Quality of Life Tool.
      Second, MCID is of value because it can be calculated in retrospect, whereas “anchor-based” thresholds require that each included patient be specifically asked how they rate their outcome (i.e., satisfaction) compared with how they were before; how they were before represents the anchor. (For the record, PASS can be calculated in retrospect, but this is rarely performed, as the anchor-based method, i.e., asking the patient if they are satisfied with their result, is preferred). Third, for better or worse, a quick search of https://www.arthroscopyjournal.org shows that as reporting of outcome thresholds has taken hold, reporting of MCID has been most common. In 2022, MCID was reported approximately 2.5 times more commonly than PASS and 5 times more commonly than SCB (Fig 1). Thus, MCID has value because, as the most commonly reported threshold, it most readily allows readers to compare outcomes among other published studies.
      Figure thumbnail gr1
      Fig 1Number of references yearly in Arthroscopy journal with MCID, PASS, and SCB mentioned in the title or abstract. ∗January 1 to October 23, 2022, annualized. (MCID, minimal clinically important difference; PASS, patient acceptable symptomatic state; SCB, substantial clinical benefit.)
      However, we believe that the focus on MCID, compared with PASS or ultimately SCB, is not better but worse, which brings us back to our very simple point. MCID is too low a bar. Patients require satisfaction (PASS). And, frankly, our purpose is to provide patients with SCB. Minimal is not substantial.
      To learn more, readers can study “Guidelines for Proper Reporting of Clinical Significance Including Minimal Clinically Important Difference (MCID), Patient Acceptable Symptomatic State (PASS), Substantial Clinical Benefit (SCB), and Maximal Outcome Improvement (MOI)”
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Waterman B.
      • Dhawan A.
      Guidelines for proper reporting of clinical significance including minimal clinically important difference, patient acceptable symptomatic state, substantial clinical benefit, and maximal outcome improvement.
      by Harris, Brand, Cote, Waterman, and Dhawan in the current issue of Arthroscopy. This article represents the latest contribution to the Arthroscopy Research Pearls Article Collection (https://www.arthroscopyjournal.org/pearls) and a timely follow-up to our award-winning Most Cited Article published in 2017 by Harris, Brand, Cote, Faucett, and Dhawan.
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Faucett S.C.
      • Dhawan A.
      Research pearls: The significance of statistics and perils of pooling. Part 1: Clinical versus statistical significance.
      ,
      • Brand J.C.
      • Rossi M.J.
      • Lubowitz J.H.
      Arthroscopy honors award winning articles and authors: Our annual research awards.
      In their current article, Harris et al.
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Waterman B.
      • Dhawan A.
      Guidelines for proper reporting of clinical significance including minimal clinically important difference, patient acceptable symptomatic state, substantial clinical benefit, and maximal outcome improvement.
      provide a nuanced guide to incorporating and understanding the use of MCID, PASS and SCB in clinical studies. Moreover, Harris et al.
      • Brand J.C.
      • Rossi M.J.
      • Lubowitz J.H.
      Arthroscopy honors award winning articles and authors: Our annual research awards.
      expand on our knowledge of yet another outcome threshold, MOI.
      • Brand J.C.
      • Rossi M.J.
      • Lubowitz J.H.
      Arthroscopy honors award winning articles and authors: Our annual research awards.
      MOI addresses the challenge of a “ceiling effect” in cases in which some patients (or patient groups), such as high-level athletes, show high baseline or pretreatment outcome scores. High pretreatment scores may result in little improvement in score from before to after treatment, even when a patient achieves SCB or a perfect result. MOI addresses the ceiling effect by effectively “normalizing” such a patient’s high pretreatment score.
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Waterman B.
      • Dhawan A.
      Guidelines for proper reporting of clinical significance including minimal clinically important difference, patient acceptable symptomatic state, substantial clinical benefit, and maximal outcome improvement.
      Harris et al.
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Waterman B.
      • Dhawan A.
      Guidelines for proper reporting of clinical significance including minimal clinically important difference, patient acceptable symptomatic state, substantial clinical benefit, and maximal outcome improvement.
      also reiterate the important point that all of these threshold scores are patient-level metrics and should be reported as the percentage of patients who meet the threshold, and not reported as to whether, as a group, the mean score for the cohort meets the threshold or not (which is a common error).
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Waterman B.
      • Dhawan A.
      Guidelines for proper reporting of clinical significance including minimal clinically important difference, patient acceptable symptomatic state, substantial clinical benefit, and maximal outcome improvement.
      In 2023, we need to raise the bar. MCID neither addresses whether patients are satisfied nor whether patients have benefited substantially from our treatments. It is acceptable to report MCID, but we also need to report PASS, SCB and, in unique patients like high-level athletes, we also may need to report MOI.
      So, imagine treating patients…“It isn’t hard to do.”
      Genius.com. Imagine by John Lennon..
      Now, imagine that a very high percentage of your patients express satisfaction (PASS), as a result your treatment. Imagine that they benefit substantially (SCB). Imagine that improve maximally (MOI).
      Imagine more than MCID. That’s what we’re singing about.

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      1. Genius.com. Imagine by John Lennon..
        https://genius.com/John-lennon-imagine-lyrics
        Date accessed: November 2, 2022