Molino Janine, Harrington Joseph, Racine-Avila Jennifer, Aaron Roy
Lifespan Biostatistics Core, Rhode Island Hospital, Providence, RI, USA.
Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Providence, RI, USA.
Orthop Res Rev. 2022 Feb 17;14:35-42. doi: 10.2147/ORR.S349268. eCollection 2022.
The minimal clinically important difference (MCID) is a way of dichotomizing data for assessment of success or failure based on clinically meaningful changes. The magnitude of the MCID is often misunderstood to be a singular quantity applicable across studies. However, substantial differences have been reported among MCIDs for the same outcome measures usually based upon differences extrinsic to the calculation. This study explores the effects of variabilities intrinsic to the calculation of the MCID.
The MCIDs for two knee replacement patient-reported outcomes measures of pain and function were calculated at 1 year postoperative with an integrative anchor and distribution-based method using external anchor questions and receiver operator characteristic (ROC) curves. The effects upon the magnitude and precision of the MCIDs of varying the anchor questions, the thresholds for success/failure, and the sample sizes were examined.
Wide variabilities were observed in both the magnitudes and precision of the MCIDs. The threshold for success had the largest effect on magnitude of pain scores, while the sample size had the largest effect on precision. For function scores, the sample size had the largest effect on magnitude, and the anchor question had the largest effect on precision.
Comparisons among MCIDs are difficult to interpret if elements of the calculations are different and influence the results. While factors extrinsic to the calculations, e.g., study population, trial design, methods of calculation, etc., are known to produce differences in the magnitude of MCIDs, this study shows that more subtle and less obvious factors intrinsic to the calculations have profound effects on both the magnitude and precision of MCIDs. Comparisons among MCIDs should be made with caution and call for greater transparency in reporting intrinsic methods. It is probably advisable for individual studies to calculate their own MCIDs and not rely on published values.
最小临床重要差异（MCID）是一种基于临床有意义的变化将数据二分以评估成功或失败的方法。MCID的大小常常被误解为一个适用于所有研究的单一数值。然而，通常基于计算外部因素的差异，同一结局指标的MCID之间已报告存在显著差异。本研究探讨了MCID计算中内在变异性的影响。
采用综合锚定和基于分布的方法，利用外部锚定问题和受试者操作特征（ROC）曲线，计算了膝关节置换术后1年患者报告的疼痛和功能两项结局指标的MCID。研究了改变锚定问题、成功/失败阈值和样本量对MCID大小和精度的影响。
MCID的大小和精度均存在较大变异性。成功阈值对疼痛评分大小的影响最大，而样本量对精度的影响最大。对于功能评分，样本量对大小的影响最大，而锚定问题对精度的影响最大。
如果计算要素不同并影响结果，MCID之间的比较就很难解释。虽然已知计算外部因素，如研究人群、试验设计、计算方法等，会导致MCID大小的差异，但本研究表明，计算中更细微和不明显的内在因素对MCID的大小和精度都有深远影响。MCID之间的比较应谨慎进行，并要求在报告内在方法时提高透明度。对于个别研究来说，计算自己的MCID而不是依赖已发表的值可能是明智的。
