A new approach to the qualitative evaluation of functional disability in dementia

Background. Dementia patients suffer from the progressive deterioration of cognitive and functional abilities. Instrumental disabilities usually appear in the earlier stages of the disease while basic disabilities appear in the more advanced stages. In order to differentiate between mild, moderate and severe patients both instrumental and basic functional disabilities should be taken into account simultaneously. Objectives. The objective of this study was to find a new method for classifying dementia patients based on their disabilities by using a basic and an instrumental Activities of Daily Living (ADL) scale. Methods. Functional disability was assessed in a Belgian cohort of dementia patients using the Katz and Lawton Instrumental Activities of Daily Living (IADL) scales. A k-means derived clustering method allocated patients to disability clusters according to their Katz and Lawton scores. In order to validate the classification, we compared socio-demographic, clinical and costs parameters between the groups. Results. The clustering method allocated patients between three clusters: dependent, non-dependent with instrumental functional disability (ND-IFD) and non-dependent. Dependence, as defined by these clusters, significantly correlates with age, residential setting, MMSE, patient's quality of life and costs. Conclusion. This new classification of patients suffering from dementia will provide better understanding of functional disabilities and will complement the evaluation of disease severity based on cognitive function. Copyright (C) 2003 John Wiley Sons, Ltd.