To present reliability data on the Multidomain Impairment Rating (MIR) scale for potential use in frontotemporal lobar degeneration (FTLD) spectrum disorders.

The standard 6-domain Clinical Dementia Rating (CDRstd) and 8-item FTLD-CDR were developed to capture the key clinical and functional aspects of patients with dementia. Since other features such as parkinsonism, motor neuron disease (MND), apraxia, etc., often occur in FTLD, the 12-item MIR scale was developed to encompass all key manifestations of the FTLD spectrum disorders for use in natural history studies and clinical trials. The MIR involves elements of the FTLD-CDR plus a visuospatial domain as well as domains for parkinsonism, MND and other non-cognitive/non-behavioral aspects of FTLD. The ratings of 0, 0.5, 1, 2 or 3 for each domain based on 3 data sources - the subject, informant and neuropsychology - and consensus ratings are generated such that the global (MIR) and summed score (MIR SS) are determined. 

A reliability exercise was completed involving the rating of baseline clinical and neuropsychological data in subjects participating in the ARTFL/LEFFTDS Consortium, in which 20 subjects each for 2 sites were rated (blinded to the other sites’ ratings), and the data of the 40 subjects were analyzed. The cases were selected a priori to represent clinically normal as well as MCI and more severe degrees of cognitive, behavioral and motor impairment (e.g., bvFTD, PPA, FTD with parkinsonism, and FTD with MND).

Weighted kappa statistic measured agreement. The analyses showed very good agreement for the global MIR ratings [κ=0.83 (95% CI 0.70-0.96)] and the MIR SS [κ=0.83 (95% CI 0.73-0.92)] ratings.

These findings suggest good reliability for the global MIR and MIR SS. The MIR may provide added utility to the FTLD-CDR, and could be used in natural history and clinical trials to more optimally capture the spectrum of features in FTLD.