Aims To map the Oxford Knee Score (OKS) and High Activity Arthroplasty Score (HAAS) items to a common scale, and to investigate the psychometric properties of this new scale for the measurement of knee health. Methods Patient-reported outcome measure (PROM) data measuring knee health were obtained from the NHS PROMs dataset and Total or Partial Knee Arthroplasty Trial (TOPKAT). Assumptions for common scale modelling were tested. A graded response model (fitted to OKS item responses in the NHS PROMs dataset) was used as an anchor to calibrate paired HAAS items from the TOPKAT dataset. Information curves for the combined OKS-HAAS model were plotted. Bland-Altman analysis was used to compare common scale scores derived from OKS and HAAS items. A conversion table was developed to map between HAAS, OKS, and the common scale. Results We included 3,329 response sets from 528 patients undergoing knee arthroplasty. These generally met the assumptions of unidimensionality, monotonicity, local independence, and measurement invariance. The HAAS items provided more information than OKS items at high levels of knee health. Combining both instruments resulted in higher test-level information than either instrument alone. The mean error between common scale scores derived from the OKS and HAAS was 0.29 logits. Conclusion The common scale allowed more precise measurement of knee health than use of either the OKS or HAAS individually. These techniques for mapping PROM instruments may be useful for the standardization of outcome reporting, and pooling results across studies that use either PROM in individual-patient meta-analysis.

中文翻译：

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克服膝关节置换术结果测量中的地板和天花板效应。

目的 将牛津膝关节评分 (OKS) 和高活动度关节置换评分 (HAAS) 项目映射到通用量表，并研究该新量表用于测量膝关节健康的心理测量特性。方法 测量膝关节健康状况的患者报告结果测量 (PROM) 数据是从 NHS PROM 数据集和全膝关节置换术或部分膝关节置换术试验 (TOPKAT) 中获得的。测试了通用尺度建模的假设。使用分级响应模型（适合 NHS PROM 数据集中的 OKS 项目响应）作为锚来校准 TOPKAT 数据集中的配对 HAAS 项目。绘制了组合 OKS-HAAS 模型的信息曲线。Bland-Altman 分析用于比较来自 OKS 和 HAAS 项目的常见量表分数。开发了一个转换表来映射 HAAS、OKS 和通用比例。结果 我们纳入了来自 528 名接受膝关节置换术的患者的 3,329 组反应。这些通常满足一维性、单调性、局部独立性和测量不变性的假设。在膝关节健康状况较高的情况下，HAAS 项目比 OKS 项目提供了更多信息。结合使用这两种仪器可以比单独使用任何一种仪器获得更高的测试级别信息。OKS 和 HAAS 得出的常见量表分数之间的平均误差为 0.29 logits。结论 与单独使用 OKS 或 HAAS 相比，通用量表可以更精确地测量膝关节健康状况。这些绘制 PROM 仪器的技术可能有助于结果报告的标准化，以及在个体患者荟萃分析中汇总使用 PROM 的研究的结果。