There are Considerable Inconsistencies Among Minimum Clinically Important Differences in TKA: A Systematic Review

Abstract

Background Patient-reported outcome measures (PROMs) are frequently used to assess the impact of total knee arthroplasty (TKA) on patients. However, mere statistical comparison of PROMs is not sufficient to assess the value of TKA to the patient, especially given the risk profile of arthroplasty. Evaluation of treatment effect sizes is important to support the use of an intervention; this is often quantified with the minimum clinically important difference (MCID). MCIDs are unique to specific PROMs, as they vary by calculation methodology and study population. Therefore, a systematic review of calculated MCID values, their respective ranges, and assessment of their applications is important to guide and encourage their use as a critical measure of effect size in TKA outcomes research. Questions/purposes In this systematic review of MCID calculations and reporting in primary TKA, we asked: (1) What are the most frequently reported PROM MCIDs and their reported ranges in TKA? (2) What proportion of studies report distribution-versus anchor-based MCID values? (3) What are the most common methods by which these MCID values are derived for anchor-based values? (4) What are the most common derivation methods for distribution-based values? (5) How do the reported medians and corresponding interquartile ranges (IQR) compare between calculation methods for each PROM? Methods Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review was conducted using the PubMed, EMBASE, and MEDLINE databases from inception through March 2022 for TKA articles reporting an MCID value for any PROMs. Two independent reviewers screened articles for eligibility, including any article that calculated new MCID values for PROMs after primary TKA, and extracted these data for analysis. Overall, 576 articles were identified, 38 of which were included in the final analysis. These studies had a total of 710,128 patients with a median age of 67.7 years and median BMI of 30.9 kg/m 2 . Women made up more than 50% of patients in most studies, and the median follow-up period was 17 months (range 0.25 to 72 months). The overall risk of bias was assessed as moderate using the Jadad criteria for one randomized controlled trial (3 of 5 ideal global score) and the modified Methodological Index for Nonrandomized Studies criteria for comparative studies (mean 17.2 6 1.8) and noncomparative studies (mean 9.6 6 1.3). There were 49 unique PROMs for which 233 Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Effects of magnesium sulfate on periarticular infiltration analgesia in total knee arthroplasty: a prospective, double-blind, randomized controlled trial

“…In the present study, patients who received the magnesium sulfate cocktail had dramatically lower consumption of morphine 24 h postoperatively and lower total morphine consumption, as well as lower pain scores on the VAS at 24 h postoperatively than the controls. Nevertheless, it is noteworthy that all differences in VAS scores between the groups did not surpass the minimal clinically important difference (MCID) reported [ 28 , 29 ]. Additionally, the absolute decrease in morphine consumption did not achieve the reported MCID.…”

Letter to the Editor: There are Considerable Inconsistencies Among Minimum Clinically Important Differences in TKA: A Systematic Review

“…The investigators summarized evidence reporting minimum clinically important difference (MCID) estimates for knee and hip arthroplasty patient-reported outcome measures (PROMs). The titles of these papers emphasized that "discordance abounds" [2] and that there were "considerable inconsistencies" [3] in MCID estimates. We agree with this message of substantial MCID variability, a finding reported by others [8,10].…”

“…The authors misquote the definition of MCID in the classic paper by Jaeschke and colleagues [7]. Deckey et al define MCID as the “smallest difference in a score in the domain of interest which patients perceive as beneficial” [3], but the actual definition by Jaeschke and colleagues was “the 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” [7]. The misquote is important because the original definition emphasizes consideration of both the side effects and costs of the intervention of interest (issues not considered when MCIDs are calculated), as well as comparison to a potential alternative intervention (also not considered in MCID calculations).…”

“…For MCID to be considered as a treatment effect size, it should have the same meaning for all patients. Consider, for example, the 7-point MCID recommended by Deckey et al [3] for the Oxford Knee Scale (OKS). Because OKS is ordinally scaled, a 7-point increase in one patient (for example, an improvement from 33 to 40 points) cannot be assumed to be equal to 7-point increase in another patient (such as an increase from 10 to 17 points).…”

CORR Insights®: There are Considerable Inconsistencies Among Minimum Clinically Important Differences in TKA: A Systematic Review

“…Instead, many journals have encouraged a combined approach in which "statistical significance" and confidence intervals are used to identify results that require more investigation, and multiple measures of effect size are used to convey potential practical benefit. In this way, as suggested by the authors of the current article [3], an MCID can be used to identify differences large enough to matter to a patient, and other anchorbased measures of the importance or size of an effect, such as the substantial clinical benefit, can be used to identify effects above the minimum threshold [2,10].…”