Chui H, Zhang Q
Department of Neurology, University of Southern California School of Medicine, Los Angeles, USA.
Neurology. 1997 Oct;49(4):925-35. doi: 10.1212/wnl.49.4.925.
This study examined the usefulness of the "Practice Parameters for the Evaluation of Dementia," published by the Quality Standards Subcommittee of the American Academy of Neurology (1994). The Practice Parameters are stratified according to three levels of certainty (standards, guidelines, and options), and suggest indications for the use of neuroimaging studies.
We reviewed 119 consecutive cases referred for assessment of memory loss to a university-affiliated interdisciplinary clinic. We assessed the diagnostic value of laboratory, neuropsychological, and neuroimaging studies above the standard history, neurologic, and mental status examinations. We also assessed the sensitivity and specificity of four clinical indicators (i.e., early symptom onset, noninsidious course, focal neurologic signs or symptoms, and gait disturbance) for predicting the diagnostic utility of neuroimaging studies.
The largest changes in diagnostic categories between the standard and the comprehensive diagnostic process was a 9% decrease in the diagnosis of Alzheimer's disease, a 6% increase in the diagnosis of mixed dementia (due largely to laboratory studies), and a 4% increase in the diagnosis of vascular dementia (due to neuroimaging). The clinical indicators were 82% sensitive and 50% specific in predicting that neuroimaging studies would change the diagnosis. In six cases, meaningful neuroimaging findings were not associated with any clinical indicator (5% false negatives). In 43 cases, neuroimaging provided no significant clinical findings despite the presence of an indicator (36% false positives).
In this convenience sample, diagnostic accuracy was improved to a comparable degree by laboratory and neuroimaging studies, although at a significant difference in cost. Use of the four clinical indicators would have reduced the frequency of neuroimaging studies by 33% but missed clinically meaningful information in 5%. Although imperfect, the Practice Parameters represent a first step toward improving the cost effectiveness of the dementia work-up.
本研究检验了美国神经病学学会质量标准小组委员会于1994年发布的《痴呆评估实践参数》的实用性。该实践参数根据三个确定程度级别（标准、指南和选项）进行分层，并给出了使用神经影像学检查的指征。
我们回顾了连续转至一家大学附属医院跨学科门诊进行记忆丧失评估的119例病例。我们评估了实验室检查、神经心理学检查和神经影像学检查相对于标准的病史、神经系统检查和精神状态检查的诊断价值。我们还评估了四个临床指标（即症状早期出现、病程非隐匿性、局灶性神经系统体征或症状以及步态障碍）对预测神经影像学检查诊断效用的敏感性和特异性。
标准诊断过程与全面诊断过程之间诊断类别最大的变化是，阿尔茨海默病的诊断减少了9%，混合性痴呆的诊断增加了6%（主要归因于实验室检查），血管性痴呆的诊断增加了4%（归因于神经影像学检查）。这些临床指标在预测神经影像学检查会改变诊断方面的敏感性为82%，特异性为50%。在6例病例中，有意义的神经影像学发现与任何临床指标均无关联（5%假阴性）。在43例病例中，尽管存在指标，但神经影像学检查未提供显著的临床发现（36%假阳性）。
在这个便利样本中，实验室检查和神经影像学检查在相当程度上提高了诊断准确性，尽管成本存在显著差异。使用这四个临床指标可使神经影像学检查的频率降低33%，但会遗漏5%具有临床意义的信息。尽管存在不足，但该实践参数是朝着提高痴呆症检查成本效益迈出的第一步。
