Prospective validation of consensus criteria for the diagnosis of dementia with Lewy bodies.

OBJECTIVE: To determine the validity of a clinical diagnosis of probable or possible dementia with Lewy bodies (DLB) made using International Consensus criteria.

BACKGROUND: Validation studies based on retrospective chart reviews of autopsy-confirmed cases have suggested that diagnostic specificity for DLB is acceptable but case detection rates as low as 0.22 have been suggested.

METHODS: We evaluated the first 50 cases reaching neuropathologic autopsy in a cohort to which Consensus clinical diagnostic criteria for DLB, National Institute for Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD, and National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria for vascular dementia (VaD) had been prospectively applied.

RESULTS: Twenty-six clinical diagnoses of DLB, 19 of AD, and 5 of VaD were made. At autopsy, 29 DLB cases, 15 AD, 5 VaD, and 1 progressive supranuclear palsy were identified. The sensitivity and specificity of a clinical diagnosis of probable DLB in this sample were 0.83 and 0.95. Of the five cases receiving a false-negative diagnosis of DLB, significant fluctuation was present in four but visual hallucinations and spontaneous motor features of parkinsonism were generally absent. Thirty-one percent of the DLB cases had additional vascular pathology and in two cases this contributed to a misdiagnosis of VaD. No correlations were found between the distribution of Lewy bodies and clinical features.

CONCLUSION: The Consensus criteria for DLB performed as well in this prospective study as those for AD and VaD, with a diagnostic sensitivity substantially higher than that reported by previous retrospective studies. DLB occurs in the absence of extrapyramidal features and in the presence of comorbid cerebrovascular disease. Fluctuation is an important diagnostic indicator, reliable measures of which need to be developed further.