Self-reported cognitive concerns and abilities: two sides of one coin?

OBJECTIVE: Patient-reported cognitive function can be measured using negatively worded items (concerns) and positively worded (abilities) items. It is possible that reporting abilities is less subject to the influence of emotional states. This study evaluated the relationship between cognitive concerns and cognitive abilities. METHODS: Cancer patients (N = 509; mean age = 61 years; 50% men; 86% White) completed concerns and abilities items developed by the National Institutes of Health Patient-Reported Outcomes Information System (PROMIS). Confirmatory factor analysis was used to evaluate the extent to which items were loaded on one single factor (unidimensionality). Multidimensionality was evaluated using bi-factor analysis (local factors: concerns and abilities). Slope parameters from multidimensional item response theory (IRT) and unidimensional IRT were compared to evaluate which factor solution fits best. RESULTS: Acceptable fit indices were found in both one-factor confirmatory factor analysis (comparative fit index (CFI) = 0.96; root mean squared error of approximation (RMSEA) = 0.062) and bi-factor analysis (CFI = 0.98; RMSEA = 0.043). Thus, abilities and concerns could be considered as a single dimension. Yet, high loadings on the local factor in bi-factor analysis and slope discrepancies between unidimensional IRT and multidimensional IRT indicate that abilities should be considered as a separate factor from concerns. CONCLUSIONS: Concerns and abilities could be measured using one-unidimensional item bank. Results also support measuring each construct separately. We recommend a conservative approach by measuring and reporting concerns and abilities separately. We therefore recommend two separate but co-calibrated item banks in the PROMIS network: cognitive function item bank-concerns and cognitive function item bank-abilities. Both item banks showed good psychometric properties and are available for research and clinical purposes.