METAANALYSIS OF THE HACHINSKI ISCHEMIC SCORE IN PATHOLOGICALLY VERIFIED DEMENTIAS

Our objectives were to investigate the utility of the Hachinski Ischem ic Score (HIS) in differentiating patients with pathologically verifie d Alzheimer's disease (AD), multi-infarct dementia (MID), and ''mixed' ' (AD plus cerebrovascular disease) dementia, and to identify the spec ific items of the HIS that best discriminate those dementia subtypes. Investigators from six sites participated in a meta-analysis by contri buting original clinical data, HIS, and pathologic diagnoses on 312 pa tients with dementia (AD, 191; MID, 80; and mixed, 41). Sensitivity an d specificity of the HIS were calculated based on varied cutoffs using receiver-operator characteristic curves. Logistic regression analyses were performed to compare each pair of diagnostic groups to obtain th e odds ratio (OR) for each HIS item. The mean HIS (+/- SD) was 5.4 +/- 4.5 and differed significantly among the groups (AD, 3.1 +/- 2.5; MID , 10.5 +/- 4.1; mixed, 7.7 +/- 4.3). Receiver-operator characteristic curves showed that the best cutoff was less than or equal to 4 for AD and greater than or equal to 7 for MID, as originally proposed, with a sensitivity of 89.0% and a specificity of 89.3%. For the comparison o f MID versus mixed the sensitivity was 93.1% and the specificity was 1 7.2%, whereas for AD versus mixed the sensitivity was 83.8% and the sp ecificity was 29.4%. HIS items distinguishing MID from AD were stepwis e deterioration (OR, 6.06), fluctuating course (OR, 7.60), hypertensio n (OR, 4.30), history of stroke (OR, 4.30), and focal neurologic sympt oms (OR, 4.40). Only stepwise deterioration (OR, 3.97) and emotional i ncontinence (OR, 3.39) distinguished MID from mixed, and only fluctuat ing course (OR, 0.20) and history of stroke (OR, 0.08) distinguished A D from mixed. Our findings suggest that the HIS performed well in the differentiation between AD and MID, the purpose for which it was origi nally designed, but that the clinical diagnosis of mixed dementia rema ins difficult. Further prospective studies of the HIS should include a dditional clinical and neuroimaging variables to permit objective refi nement of the scale and improve its ability to identify patients with mixed dementia.