Wong Eric, Ungvari Gabor S, Leung Siu-Kau, Tang Wai-Kwong
Centre for Epidemiology and Biostatistics, School of Public Health, Chinese University of Hong Kong, Hong Kong, China.
Int J Methods Psychiatr Res. 2007;16(3):161-70. doi: 10.1002/mpr.224.
Catatonic signs and symptoms are frequently observed in patients with chronic schizophrenia. Clinical surveys have suggested that the composition of catatonic syndrome occurring in chronic schizophrenia may be different from what is found in acute psychiatric disorders or medical conditions. Consequently, this patient population may need tailor-made rating instruments for catatonia. The aim of the present study was to examine the suitability and accuracy of using the Bush-Francis Catatonia Rating Scale (BFCRS) in chronic schizophrenia inpatients.
The unidimensionality (optimal number of items; item fit), and the scoring scheme (the optimal number of scoring categories) of the BFCRS were determined in a random sample of 225 patients with chronic schizophrenia applying Rasch analysis. In addition, differential item functioning (DIF) analysis was also performed.
The BFCRS proved to be unidimensional apart from three misfit and one marginally misfit items. The three misfit items were removed from the scale thereby constructing a revised version called BFCRS-R. Since the original BFCRS (BFCRS-O) showed no increase across items across steep gradients (poor endorsability of step calibrations), in BFCRS-R a binary scale ('absent' versus 'present' choices only) was constructed instead of the scoring scheme of 0-3. The 20-item BFCRS-R showed improved psychometric properties in that it had a higher item separation index than BFCRS-O. BFCRS-R mean logit was closer to zero indicating that the items on the scale and the subjects were better matched than in BFCRS-O. DIF analysis showed that certain items of both versions of BFCRS were influenced by the presence of negative symptoms.
BFCRS-R is shorter and simpler than the original version and having better psychometric properties seems to be better suited for identifying and quantifying catatonia in chronic psychotic patients.
紧张症的体征和症状在慢性精神分裂症患者中经常出现。临床调查表明，慢性精神分裂症中出现的紧张症综合征的构成可能与急性精神障碍或躯体疾病中的情况不同。因此，这一患者群体可能需要专门针对紧张症的评定工具。本研究的目的是检验使用布什 - 弗朗西斯紧张症评定量表（BFCRS）对慢性精神分裂症住院患者的适用性和准确性。
应用拉施分析在225例慢性精神分裂症患者的随机样本中确定BFCRS的单维性（最佳项目数；项目拟合度）和评分方案（最佳评分类别数）。此外，还进行了项目功能差异（DIF）分析。
除了3个拟合不佳和1个勉强拟合不佳的项目外，BFCRS被证明是单维的。这3个拟合不佳的项目从量表中删除，从而构建了一个修订版，称为BFCRS - R。由于原始的BFCRS（BFCRS - O）在陡峭梯度上各项目没有显示出增加（步骤校准的认可性差），因此在BFCRS - R中构建了一个二元量表（仅“不存在”与“存在”选择），而不是0 - 3的评分方案。20项的BFCRS - R显示出更好的心理测量特性，因为它比BFCRS - O具有更高的项目区分指数。BFCRS - R的平均对数几率更接近零，表明量表上的项目与受试者的匹配度比BFCRS - O更好。DIF分析表明，BFCRS两个版本的某些项目受到阴性症状的影响。
BFCRS - R比原始版本更短、更简单，并且具有更好的心理测量特性，似乎更适合于识别和量化慢性精神病患者中的紧张症。
