Ceiling Effects and Differential Measurement Precision Across Calibrated Cognitive Scores in the Framingham Study

Objective: To calibrate cognitive assessment data across multiple waves of the Framingham Heart Study (FHS), addressing study design considerations, ceiling effects, and measurement precision. Method: FHS participants completed several cognitive assessments including screening instruments and more comprehensive batteries at different study visits. We used expert opinion to assign each cognitive test item to a single domain-memory, executive function, language, visuospatial abilities, or none of the above. As part of a larger cross-study harmonization effort, we calibrated each domain separately using bifactor confirmatory factor analysis (CFA) models, incorporating item parameters for anchor items previously calibrated from other studies and freely estimating item parameters for FHS-specific items. We obtained scores and standard errors (SEs) for each participant at each study visit. We addressed psychometric considerations of ceiling effects and measurement precision. Results: Overall, memory domain scores were the most precisely estimated. Scores for all domains from visits where the Mini-Mental State Examination (MMSE) was the only test administered were imprecisely estimated and suffered from ceiling effects. Scores from visits with a more extensive battery were estimated more precisely and better differentiated between ability levels. Conclusions: The harmonized and calibrated cognitive data from the FHS should prove useful for future analyses examining cognition and cognitive decline. They will be of particular interest when combining FHS with other studies that have been similarly calibrated. Researchers should be aware of varying levels of measurement precision and the possibility of ceiling effects in their planned analyses of data from the FHS and similar studies. Key Points Question: What methods and special considerations are needed to derive calibrated cognitive factor scores and use them in future analyses in the FHS, and other similar studies that have evolving cognitive batteries over time or different batteries administered at different study visits? Findings: The FHS used different cognitive instruments at different study visits. These instruments had different measurement properties, including ceiling effects and substantial differences in measurement precision. Importance: Cognitive domain scores from the FHS data can be used in subsequent research. Investigators should consider measurement precision and ceiling effects in their analyse