Department of Orthopaedic Surgery, Elda University Hospital, Ctra Elda-Sax s/n, 03600, Elda, Alicante, Spain.
Department of Traumatology and Orthopaedia, Miguel Hernandez University, Elche, Alicante, Spain.
Knee Surg Sports Traumatol Arthrosc. 2020 May;28(5):1473-1478. doi: 10.1007/s00167-019-05543-x. Epub 2019 May 20.
There is a paucity of literature defining the minimal clinically important difference (MCID) for the Knee Society Scores (KSS) after total knee arthroplasty (TKA), and no data on the substantial clinical benefit (SCB) for KSS have been reported. The purpose of this study was to determine MCID and SCB for the KSS in patients with primary TKA.
The median age of patients was 71.6 (range 50-88) years, and 60.3% were females 507 patients with TKA were prospectively enrolled. Patients completed the KSS before surgery and at second postoperative year. The MCID values of the KSS were estimated using anchor-based method, distribution-based method and receiver operating characteristic (ROC) curve analysis with calculation of the area under curve (AUC). SCB was estimated using ROC.
The MCID for KSS-knee score was 7.2 points by the anchor-based method, 7.2 by the distribution-based method, and using a ROC analysis the cutoff point was 8.9 points with an AUC of 0.75. For KSS-function score, the MCID values were 9.7, 6.3, and 10.3 (AUC 0.71), respectively. SCB values were 39.7 points (AUC 0.74) for the KSS-knee score, and 38.6 (AUC 0.76) for the KSS-function score. Logistic regression showed age and Charlson index to negatively affect the changes in KSS.
Different methods for MCID calculation lead to different results. With the use of ROC curve analysis, patients with an improvement of at least 9 points for KSS-knee and 10 points for KSS-function scores experience a clinically important change, whereas those who have at least an improvement of 40 points for KSS-knee and 39 points for KSS-function scores experience a substantial clinical benefit. These findings can ensure clinical improvement from the patient's perspective and also aid in interpreting results from clinical studies.
III.
全膝关节置换术（TKA）后，膝关节协会评分（KSS）的最小临床重要差异（MCID）的文献定义很少，也没有报道过 KSS 的实质性临床获益（SCB）的数据。本研究的目的是确定原发性 TKA 患者 KSS 的 MCID 和 SCB。
患者的中位年龄为 71.6 岁（范围 50-88 岁），60.3%为女性。前瞻性纳入了 507 例 TKA 患者。患者在术前和术后第 2 年完成 KSS 评分。使用锚定法、分布法和接受者操作特征（ROC）曲线分析（计算曲线下面积 AUC）估计 KSS 的 MCID 值。使用 ROC 估计 SCB。
锚定法得出 KSS-膝关节评分的 MCID 为 7.2 分，分布法为 7.2 分，ROC 分析的截断点为 8.9 分，AUC 为 0.75。对于 KSS-功能评分，MCID 值分别为 9.7、6.3 和 10.3（AUC 为 0.71）。KSS-膝关节评分的 SCB 值为 39.7 分（AUC 为 0.74），KSS-功能评分的 SCB 值为 38.6 分（AUC 为 0.76）。Logistic 回归显示年龄和 Charlson 指数对 KSS 的变化有负面影响。
不同的 MCID 计算方法导致结果不同。使用 ROC 曲线分析，KSS-膝关节评分至少改善 9 分和 KSS-功能评分至少改善 10 分的患者会经历有临床意义的变化，而 KSS-膝关节评分至少改善 40 分和 KSS-功能评分至少改善 39 分的患者会经历实质性的临床获益。这些发现可以从患者的角度确保临床改善，也有助于解释临床研究的结果。
III 级。
