Translation and psychometric evaluation of a Persian version of the functional assessment staging scale (I-FAST) in older patients with mild cognitive impairment and Alzheimer’s disease in Iran

The Functional Assessment Staging procedure is a clinical instrument which has been designed for staging Alzheimer’s disease (AD) from the stage of no deficits to the pre-clinical stage of subjective deficits, to Mild Cognitive Impairment (MCI), to the stages of AD. This study examined the psychometric properties and the validity of the Persian version of the FAST (I-FAST) in an elderly outpatient population in Iran. We conducted a validation study of the FAST scale at the two referral centers for dementia and cognitive disorders in Tehran, Iran. The participants consisted of subjects with normal cognition, MCI and AD. The scores of the Persian version of the Mini-Mental State Examination (MMSE) and the Persian version of the I-FAST were examined. Demographic variables were also collected. The diagnosis of MCI was made based on Petersen criteria and AD based on the McKhann et al. criteria by a neurologist with expertise in dementia. Data was collected from 219 participants. A total of 54.7% of the sample was female and their mean age was 72.54 ± 8.88 years. The area under the ROC curve was calculated 0.952 and 0.982. The I-FAST had a sensitivity of 92.2% and specificity of 98.0% for the differentiation of normal cognition from MCI. The sensitivity of the I-FAST for discrimination of subjects with AD from MCI was 99.0% and the specificity was 93.7%. The I-FAST showed good psychometric characteristics in the discrimination of MCI from both normal elderly and patients with Alzheimer’s. The I-FAST is also a sensitive and accurate instrument for staging persons at risk for MCI and Alzheimer’s, relatively free of the confounding effects of education, culture and language in comparison with the MMSE.