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Table 1 Articles meeting inclusion criteria applying IRT methods to cognitive measures of dementia

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

  

(US)

(UK)

 

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

  1. AD = Alzheimer’s disease, MCI = mild cognitive impairment, MMSE = Mini Mental State Examination, ADAS-cog = Alzheimer’s disease Assessment Scale-Cognitive subscale, BIMCT = Blessed Information Memory Concentration Test.