Santor Darcy A, Ascher-Svanum Haya, Lindenmayer Jean-Pierre, Obenchain Robert L
School of Psychology, University of Ottawa, Ottawa, Canada, and The Provincial Centre of Excellence for Child and Youth Mental Health, Ottawa, Ontario, Canada.
BMC Psychiatry. 2007 Nov 15;7:66. doi: 10.1186/1471-244X-7-66.
Statistical models based on item response theory were used to examine (a) the performance of individual Positive and Negative Syndrome Scale (PANSS) items and their options, (b) the effectiveness of various subscales to discriminate among individual differences in symptom severity, and (c) the appropriateness of cutoff scores recently recommended by Andreasen and her colleagues (2005) to establish symptom remission.
Option characteristic curves were estimated using a nonparametric item response model to examine the probability of endorsing each of 7 options within each of 30 PANSS items as a function of standardized, overall symptom severity. Our data were baseline PANSS scores from 9205 patients with schizophrenia or schizoaffective disorder who were enrolled between 1995 and 2003 in either a large, naturalistic, observational study or else in 1 of 12 randomized, double-blind, clinical trials comparing olanzapine to other antipsychotic drugs.
Our analyses show that the majority of items forming the Positive and Negative subscales of the PANSS perform very well. We also identified key areas for improvement or revision in items and options within the General Psychopathology subscale. The Positive and Negative subscale scores are not only more discriminating of individual differences in symptom severity than the General Psychopathology subscale score, but are also more efficient on average than the 30-item total score. Of the 8 items recently recommended to establish symptom remission, 1 performed markedly different from the 7 others and should either be deleted or rescored requiring that patients achieve a lower score of 2 (rather than 3) to signal remission.
This first item response analysis of the PANSS supports its sound psychometric properties; most PANSS items were either very good or good at assessing overall severity of illness. These analyses did identify some items which might be further improved for measuring individual severity differences or for defining remission thresholds. Findings also suggest that the Positive and Negative subscales are more sensitive to change than the PANSS total score and, thus, may constitute a "mini PANSS" that may be more reliable, require shorter administration and training time, and possibly reduce sample sizes needed for future research.
基于项目反应理论的统计模型用于检验：(a) 阳性和阴性症状量表（PANSS）各项目及其选项的性能；(b) 各种分量表在区分症状严重程度个体差异方面的有效性；(c) 安德烈亚森及其同事（2005年）最近推荐的用于确定症状缓解的临界分数的适宜性。
使用非参数项目反应模型估计选项特征曲线，以检验30个PANSS项目中每个项目的7个选项中每个选项被认可的概率，该概率是标准化总体症状严重程度的函数。我们的数据是1995年至2003年期间纳入一项大型自然观察性研究或12项将奥氮平与其他抗精神病药物进行比较的随机双盲临床试验之一的9205例精神分裂症或分裂情感性障碍患者的PANSS基线评分。
我们的分析表明，构成PANSS阳性和阴性分量表的大多数项目表现良好。我们还确定了一般精神病理学分量表中项目和选项需要改进或修订的关键领域。阳性和阴性分量表分数不仅比一般精神病理学分量表分数更能区分症状严重程度的个体差异，而且平均而言比30项总分更有效。在最近推荐用于确定症状缓解的8个项目中，有1个项目与其他7个项目的表现明显不同，要么应删除，要么重新计分，要求患者达到更低的2分（而非3分）以表明缓解。
对PANSS的首次项目反应分析支持其良好的心理测量特性；大多数PANSS项目在评估疾病总体严重程度方面要么非常好，要么良好。这些分析确实识别出了一些项目，这些项目在测量个体严重程度差异或定义缓解阈值方面可能需要进一步改进。研究结果还表明，阳性和阴性分量表比PANSS总分对变化更敏感，因此可能构成一个“迷你PANSS”，可能更可靠，需要更短的施测和培训时间，并可能减少未来研究所需的样本量。
