Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada.
Clin J Pain. 2013 Jun;29(6):499-506. doi: 10.1097/AJP.0b013e318269569c.
To evaluate the properties of the Pain Catastrophizing Scale (PCS) from a Rasch paradigm.
A secondary analysis of 235 patients with work-related pain conditions was performed using the Rasch methodology. Unidimensionality, item fit, location independence, differential item functioning, response option structure, and linearity were evaluated for the 13-item PCS score.
Two items (8 and 12) required rescoring to address disordered response thresholds. Significant misfit to the Rasch model was corrected through the use of testlets based on the original 3 factors of the PCS (rumination, magnification, and helplessness). After rescoring and creation of testlets, the scale showed good fit to the Rasch model (χ(2)=6.93, P=0.91) and could be logically considered an interval-level scale. No evidence of differential item functioning was found for sex or location of pain. The items in the scale covered the spectrum of catastrophizing levels reported by the sample. A transformation matrix is presented that allows simple conversion of ordinal to interval-level scores.
The results of this secondary analysis suggest that the PCS can be appropriately evaluated as an interval-level scale when the composite 13-item score is considered, as has been standard practice to date. Implications for clinical and research use are discussed.
从 Rasch 范式评估疼痛灾难化量表（PCS）的特性。
使用 Rasch 方法对 235 名与工作相关的疼痛患者进行二次分析。评估了 13 项 PCS 得分的单维性、项目拟合、位置独立性、差异项目功能、反应选项结构和线性。
有两个项目（8 和 12）需要重新评分以解决无序响应阈值问题。通过使用基于 PCS 原始 3 个因素（反刍、放大和无助）的测验模块来纠正对 Rasch 模型的显著拟合不良。重新评分和创建测验模块后，该量表很好地符合 Rasch 模型（χ²=6.93，P=0.91），并且可以合理地视为区间量表。未发现性别的差异项目功能或疼痛的位置。量表中的项目涵盖了样本报告的灾难化水平的范围。本文提出了一个转换矩阵，可以将有序得分转换为区间得分。
本次二次分析的结果表明，当考虑综合的 13 项得分时，PCS 可以适当评估为区间量表，这是迄今为止的标准做法。讨论了其在临床和研究中的应用。
