Psychometric Evaluation of the Korean Version of PROMIS Self-Efficacy for Managing Symptoms Item Bank: Item Response Theory

Abstract

Summary: Purpose: To evaluate the psychometric properties of the Patient-Reported Outcomes Measurement Information System (PROMIS) self-efficacy for managing symptoms of the version 1.0 item bank in Korea. Methods: This study consisted of two phases: first, developing the Korean version of the item bank following the translation guidelines; and second, performing a cross-sectional study to evaluate its psychometric properties using the item response theory. This study enrolled 323 patients with type 2 diabetes mellitus between July and August 2020. Cronbach's α was used to assess the reliability of this item bank. Confirmatory factor analysis, using diagonally weighted least squares, was used to identify the assumptions of item response theory. Item parameter estimates including discrimination and thresholds were derived using the graded response model of the item response theory to reflect patient-reported outcomes as individualized responses. Results: The Korean version of the item bank demonstrated good reliability (Cronbach's α = .98) and its discrimination ranged from 1.82 to 4.93. The thresholds resulted in the establishment of a category response curve for each item. However, no overlap was observed among the category curves. Moreover, the differential item functioning was not significant for age, gender, and income variables. Conclusion: The graded response model and differential item functioning provided qualitative evidence that demonstrated acceptable psychometric properties of symptom management self-efficacy among patients. This item bank is expected to provide adequate assessments of self-efficacy of symptom management for patients with a chronic disease, which can contribute to nursing research and intervention.

Keywords

• Patient reported outcome measures
• psychometrics
• self-efficacy
• validity study