Development and validation of an end stage kidney disease awareness survey: Item difficulty and discrimination indices

Abstract

Introduction Lack of awareness for chronic kidney disease (CKD), including end stage kidney disease (ESKD) and their management options is a major impediment to patients being able to select and use home dialysis therapies. While some instruments have been developed to measure CKD awareness, we lack validated instruments to evaluate patients’ awareness of ESKD and dialysis modalities. This study is part of multipart project for developing and validating an ESKD-centric disease awareness questionnaire. Methods A team of specialty renal care experts developed a 45-items questionnaire encompassing the subdomains of General Kidney Knowledge, CKD Knowledge, and ESKD Knowledge. Item reduction analysis—specifically, calculation of item difficulty and item discrimination index scores—was used to items for further review and potential removal. Results Index scores were reviewed in conjunction with consideration of theoretical and substantive item content to reduce the number of items in the questionnaire, resulting in a 32-item questionnaire, retaining 5/10 items in the general kidney knowledge subdomain, 14/21 items in the CKD knowledge subdomain, and 13/14 items in the ESKD knowledge subdomain. Retained items ranged from 0.19 to 0.79 on the difficulty index, and from 0.31 to 0.81 on the discrimination index. Scores for percent correct on the reduced questionnaire spanned 0% to 87.5% correct on the full scale, 0% to 100% correct on the General Knowledge subdomain, 0% to 100% on the CKD Knowledge subdomain, and 0% to 92.3% on ESKD Knowledge subdomain. Conclusions The questionnaire developed and refined in this study constitutes a patient disease awareness instrument that spans a range of difficulty, and yet shows strong ability to distinguish between patients with varying levels of disease awareness. This study is the first in part of a multistep project to addresses a gap in measuring ESKD specific knowledge. Accurate assessment of patients’ disease awareness through a validated instrument can allow identification of knowledge domains leading to positive impacts on their healthcare decisions and improve targeted patient education efforts.