Harmonized cognitive performance in an older adult cohort of Vietnamese American immigrants: The VIP study

INTRODUCTION: Vietnamese Americans represent an understudied population with unique risk factors relevant to cognitive aging. The current study sought to model global cognition in the Vietnamese Insights into Cognitive Aging Program (VIP) study and harmonize ability estimates with the National Alzheimer's Coordinating Center (NACC) Uniform Data Set. METHODS: Cognitive data from VIP (N = 548) and NACC (N = 15,923) were analyzed using item response theory. Seven common items were assessed for differential item functioning (DIF); items without salient DIF were used to harmonize the cognitive composite score across the two cohorts. RESULTS: Although five of the seven common items showed evidence of DIF, the magnitude of this DIF was negligible, affecting the factor score estimates of only 12 (2.19%) VIP participants by more than one standard error. DISCUSSION: Global cognitive functioning can be estimated in Vietnamese American immigrants with minimal bias and psychometrically matched to one of the largest studies of cognitive aging and dementia worldwide. HIGHLIGHTS: This is the first known study to model cognition in older Vietnamese Americans. Global cognition was harmonized with minimal bias across two diverse cohorts. Differential item functioning was found in five of seven items, but the impact was not salient. Results create new opportunities to study health disparities in an underrepresented group.