Short- and long-term efficacy of cholinesterase inhibitors in older adults with alzheimer's disease and mixed dementia: results of a 21-month observational study.

The high cost of cholinesterase inhibitors (ChEIs) makes it crucial for the clinician to accurately identify subjects who will benefit from treatment. In Italy ChEI efficacy is assessed after 3 months, but this time interval may not be enough to know whether to continue or abandon the treatment. The aim of the study was to establish whether identifying responders (R) to ChEI on the strength of a 3--month treatment suffices to predict long--term stability in patients with dementia.For the study, 336 patients with dementia treated with ChEIs were assessed. They were considered as R when Mini--Mental State Examination (MMSE) score was stable or improved after 3 or 9 months of ChEIs, and as persistently stable if MMSE score dropped by <2 points in 21 months. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) were calculated to test response at 3 or 9 months vis--à--vis 21 months persistent stability.For response assessment at 3 months, sensitivity was 0.83 and specificity 0.58, whereas at 9 months sensitivity was 0.84 and specificity 0.73. When age, sex, years of education, ChEI type, and antipsychotic/antidepressant drugs were included in the linear regression model with long--term variations in MMSE score, only MMSE variations between 0--3 and 0--9 months were significantly associated with long--term stability.in Italian patients, assessing response later on (after 6--9 months of treatment instead of 3) seems better able to distinguish between patients who will or will not benefit in the long--term from ChEI treatment.