Supplementary Material for: A Common Metric for Self-Reported Severity of Personality Disorder

Introduction: Dimensional models of personality disorders (PD) in the DSM-5 and ICD-11 share a focus on impairments in self and interpersonal functioning to represent the general features and severity of PD. This new perspective has led to the development of numerous measures for assessing individual differences in PD severity. While this improves choices for researchers and practitioners, it also poses the challenge of an increasing lack of standardization. Objective: The aim of this study is to establish a common metric across 6 widely used self-report measures of PD severity using item response theory models. Methods: 849 participants completed a survey including the Inventory of Personality Organization – 16-item version (IPO-16), the Level of Personality Functioning Scale – Brief Form 2.0, the Level of Personality Functioning Scale – Self-Report, the Operationalized Psychodynamic Diagnosis – Structure Questionnaire Short Form, the Personality Inventory for DSM-5 – Brief Form Plus and the Standardized Assessment of Severity of Personality Disorder (SASPD). We fitted exploratory multidimensional graded response models and used bifactor rotation to extract a general factor across measures. Factor scores were linked to representative T scores using data from a representative survey of 2,502 participants who completed the IPO-16. Results: When using bifactor rotation in a 7-factor model, all items loaded positively on the general factor, and the general factor explained 65.5% of the common variance. With the exception of the SASPD, all measures provided highly discriminating items (factor loadings >0.70) for measuring the general factor and reached an acceptable reliability (>0.80) across a wide range of the latent continuum. We constructed a crosswalk table linking total scores of the 6 measures to each other and to representative T scores. Conclusions: Our results suggest that 6 different self-report measures of the severity of PD capture a strong common factor and can therefore be scaled along a single latent continuum. Our results may facilitate instrument-independent assessment of severity of PD and increase comparability across studies.

引言：DSM-5及ICD-11中关于人格障碍（PD）的维度模型均聚焦于自我及人际功能损害，以此呈现PD的普遍特征及其严重程度。这一新颖的视角促使众多评估PD严重程度个体差异的测量方法得以发展。尽管这为研究人员和从业者提供了更多选择，但也带来了标准化程度不断降低的挑战。研究目的：本研究的目的是利用项目反应理论模型，在6种广泛使用的PD严重程度自我报告测量工具之间建立一个共同的指标。研究方法：849名参与者完成了一项调查，包括人格组织量表-16项版本（IPO-16）、人格功能水平量表-简版2.0、人格功能水平量表-自我报告、操作性心理诊断-结构问卷简表、DSM-5人格量表-简版加长版以及人格障碍严重程度标准化评估（SASPD）。我们拟合了探索性的多维分级反应模型，并使用双因素旋转提取了跨测量的一般因素。通过从完成了IPO-16的2,502名参与者的代表性调查数据中，将因素得分与代表性的T分数相联系。研究结果：在7因素模型中使用双因素旋转时，所有项目均正负荷于一般因素上，且一般因素解释了65.5%的共同方差。除SASPD外，所有测量工具都提供了高度区分性的项目（因素负荷>0.70），用于测量一般因素，并在广泛的潜在连续体上达到了可接受的信度（>0.80）。我们构建了一个交叉对照表，将6种测量工具的总分数相互联系，并与代表性的T分数相联系。研究结论：我们的结果表明，6种不同的PD严重程度自我报告测量工具捕捉到了一个强烈的共同因素，因此可以沿着单一潜在连续体进行标度。我们的研究结果可能有助于独立于测量工具的PD严重程度评估，并增加研究间的可比性。