INTRODUCTION: Assessment of cognitively complex instrumental activities of daily living (IADL) is important in (incipient) dementia, but little is known about the influence of cultural differences. We aim to investigate the cross-cultural comparability of IADL. METHODS: IADL were measured in 3,571 individuals (67.1 +- {\pm} 9.5 years old, 44.7\% female) in 11 international studies using the Amsterdam IADL Questionnaire (A-IADL-Q). Cultural, age and gender bias were assessed on item level using differential item functioning (DIF) and on scale level by calculating correlations between IADL and cognitive and functional measures . RESULTS: We did not find meaningful bias on item or on scale level, as indicated by low DIF effect sizes (  R2 range 0-0.03) and correlations in expected directions and of similar magnitude. DISCUSSION: Our results suggest that IADL may be universally suitable as outcome measure. The A-IADL-Q seems robust to demographic diversity and is capable of reliably measuring IADL impairment .
INTRODUCTION: To understand the potential influence of diversity on the measurement of functional impairment in dementia, we aimed to investigate possible bias caused by age, gender, education, and cultural differences. METHODS: 3,571 individuals (67.1 {\pm} 9.5 years old, 44.7\% female) from the Netherlands, Spain, France, United States, United Kingdom, Greece, Serbia and Finland were included. Functional impairment was measured using the Amsterdam IADL Questionnaire . Item bias was assessed using differential item functioning (DIF) analysis . RESULTS: There were some differences in activity endorsement. A few items showed statistically significant DIF. However, there was no evidence of meaningful item bias: effect sizes were low ( \Delta R2 range 0-0.03) . Impact on total scores was minimal. DISCUSSION: The results imply a limited bias for age, gender, education and culture in the measurement of functional impairment. This study provides an important step in recognizing the potential influence of diversity on primary outcomes in dementia research .
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Assessment of cognitively complex instrumental activities of daily living (IADL) is important in (incipient) dementia, but little is known about the influence of
To understand the potential influence of diversity on the measurement of functional impairment in dementia, we aimed to investigate possible bias caused by age, gender, education, and
R
We aim to investigate the cross-cultural comparability of IADL. METHODS: IADL were measured in
METHODS:
D
+-
R
in 11 international studies
from the Netherlands, Spain, France, United States, United Kingdom, Greece, Serbia and Finland were included. Functional impairment was measured
R
(A-IADL-Q). Cultural, age and gender bias were assessed on item level
. Item bias was assessed
R
and on scale level by calculating correlations between IADL and cognitive and functional measures
analysis
R
We did not find meaningful bias on item or on scale level, as indicated by low DIF effect sizes (
There were some differences in activity endorsement. A few items showed statistically significant DIF. However, there was no evidence of meaningful item bias: effect sizes were low (
A
\Delta
R
and correlations in expected directions and of similar magnitude. DISCUSSION: Our results suggest that IADL may be universally suitable as outcome measure. The A-IADL-Q seems robust to demographic diversity and is capable of reliably measuring IADL impairment
. Impact on total scores was minimal. DISCUSSION: The results imply a limited bias for age, gender, education and culture in the measurement of functional impairment. This study provides an important step in recognizing the potential influence of diversity on primary outcomes in dementia research