Instrumental activities of daily living (iADLs) are critical in aging and neurodegenerative research, both diagnostically (e.g., distinguishing dementia from mild cognitive impairment) and as endpoints for trials maintaining or improving functioning. However, measurement has not consistently kept pace with a changed world wherein the ability to navigate technology is pertinent to maintaining independent functioning. The current study used harmonization approaches to link traditional and technological iADLs measures using two samples.

262 individuals (53.4% women, 91.7% non-Hispanic White, Mage = 76.2, Meducation = 15.6) completed both measures: (1), the Functional Activities Questionnaire (FAQ), and (2), the new Expanded FAQ. Item response theory (IRT) analyses extracted item parameters to characterize measure psychometrics and accurately determine individual functional ability. Harmonization was done using both nonequivalent groups anchor test (NEAT) and equipercentile linking methods with supplementary traditional iADL parameter estimates from the National Alzheimer Coordinating Center (n = 48,605).

Correlations verified the measures were sufficiently related (rs = .79), and confirmatory factor analyses and reliability determined all items assessed a single construct. Items from both measures complemented each other to provide more information about milder and more severe functional change. NEAT models converged to provide IRT linking equations and equipercentile conversation tables.

This study provides critical information for harmonizing evolving technological iADLs with traditional iADLs that are assessed in longstanding cohorts. It further provides support for use of an expanded FAQ.