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

Area of Science:

• Orthopedics
• Health Outcomes Research
• Biostatistics

Background:

• Patient-reported outcome measures (PROMs) are crucial for assessing total knee arthroplasty (TKA) effectiveness.
• Statistical comparisons alone are insufficient; effect sizes, like minimum clinically important difference (MCID), are vital for evaluating TKA value.
• MCIDs vary by calculation method and population, necessitating a systematic review for consistent application in TKA research.

Purpose of the Study:

• To systematically review reported MCID values and their ranges for PROMs in primary TKA.
• To determine the proportion of studies using distribution-based versus anchor-based MCID calculations.
• To identify common derivation methods for both anchor-based and distribution-based MCIDs and compare their results.

Main Methods:

• A systematic review of PubMed, EMBASE, and MEDLINE databases (up to March 2022) was conducted for TKA articles reporting MCID values for PROMs.
• Data from 38 eligible studies (710,128 patients) were extracted, including MCID values, calculation methods, and demographics.
• Risk of bias was assessed using Jadad criteria and modified Methodological Index for Non-randomized Studies.

Main Results:

• WOMAC Function and Pain subscores were the most frequently reported MCIDs (9% each).
• Anchor-based MCIDs for WOMAC Function and Pain were 23 and 25, respectively; distribution-based were 11 and 22.
• Anchor-based methods were used by 39% of studies, distribution-based by 32%, and both by 29%. Patient satisfaction/pain relief Likert scales were common anchors.
• Most reported median MCID values did not significantly differ by calculation method for the same PROM.

Conclusions:

• Despite variability, methodologies for deriving MCIDs in TKA research show consistency.
• A consensus exists regarding MCID values across most PROMs, irrespective of the calculation method.
• Standardized reporting of MCID values is recommended for improved clinical decision-making and patient safety in TKA.