From: Item response theory analysis of cognitive tests in people with dementia: a systematic review
Study | Ashford et al.[46] | Mungas & Reed[1] | Gibbons et al.[48] | Benge et al.[49] | |
---|---|---|---|---|---|
Country | USA | USA | USA and UK | USA | |
Setting | Geriatric psychiatry | Two clinical sites of Alzheimer’s disease centre | Two community based samples from USA and UK | Alzheimer’s disease and memory disorders clinic | |
Outpatient clinic | |||||
N | 86 | 1207 | 540 (US: 401, UK: 139) | 1087 | |
Sex | 73.2% female | 64.7% female | (US) 64% female | 66.6% female | |
(UK)75% female | |||||
Age | Â | Â | (US) | (UK) | Â |
Mean | 74 | 76 | 82 | 84.7 | 75 |
SD | 8 | 8.9 | 4.7 | 5.3 | 8.1 |
Range | 53-91 | 39-100 | > 75 | >75 | Not reported |
Etiology; n (%) | Probable AD: 52 (60) | Probable AD: 592 (49.0) | UK: AD: 139 (100) | AD: 1044 (96) | |
Possible AD: 34 (40) | Possible AD: 176 (14.6) | US: Probable AD: 338 (84.2) | MCI: 43 (4) | ||
Vascular: 60 (5.0) | Possible AD: 63 (15.7) | ||||
Mixed and other dementia: 325 (26.9) | |||||
No cognitive impairment: 27 (2.2) | |||||
Diagnosis deferred: 27 (2.2) | |||||
Dementia severity | Mean MMSE=18 | Mean MMSE= 17.7 | US: Mean MMSE=19.6 | Mean ADAS cog=31.2 | |
SD=7.1 | SD=7.3 | SD=4.9 | SD=16.5 | ||
Range=1-29 | Range=0-30 | Range=1-29 | Range=not reported | ||
Mean BIMCT= 16.9 | UK: Mean MMSE=16.5 | ||||
SD=8.3 | SD=5.5 | ||||
Range=0-33 | Range=0-25 | ||||
Cognitive measure | MMSE | MMSE, BIMCT | MMSE | ADAS-cog | |
IRT method | Item characteristic curve analysis | Two-parameter model | Item characteristic curve analysis | Samejima’s graded model | |
Outcome | Hierarchy of item difficulty and discrimination | Hierarchy of item difficulty of Global function scale. Investigation of linearity of MMSE, BIMCT and global function. | Hierarchy of item difficulty from 2 samples | Discrimination and information statistics on ADAS-cog test as whole, plus domains and subscales |