We have read with interest the article by Ernst et al1 on the association between cognitive decline and the costs of Alzheimer disease (AD). The authors found no significant association between patients' Mini-Mental State Examination (MMSE) score and indirect cost, as defined by hours spent by caregivers for patients' assistance.
With the aim to obtain detailed estimates of the direct and indirect costs of AD in Italy, we performed a longitudinal study from 1994 to 1996.2 A sample of 103 patients with AD (77% women; mean[±SD] age, 77.7±7.3 years; mean[±SD] MMSE score, 10.2±7.5; 34% had a Clinical Dementia Rating [CDR] scale score of 1, 25% had a CDR score of 2, and 41% had a CDR score of 3) living at home were included. Clinical assessment, including MMSE score and functional status measured through the number of basic activity of daily living3 (ADL) and instrumental4 ADL (IADL) abilities lost, was performed at baseline evaluation, and after 6 and 12 months. In addition, weekly home visits were conducted for 1 year to obtain accurate information of the components of the costs. The annual net costs per person for caregivers' in-home caring activities (included surveillance) was $33000 in US dollars, a figure close to that estimated by Ernst and coworkers.1 In Table 1the results of the regression analysis are showed. In part 1 of Table 1 the dependent variable is the logarithm of the patients' annual indirect costs. In equation A (Table 1) MMSE score is not significantly related to indirect costs. This result is similar to that reported by Ernst and coworkers, also in term of its R2 value.