Validation of a new self-administered dietary salt intake questionnaire in patients with chronic kidney disease.

Excessive salt intake contributes to hypertension, heart failure, and chronic kidney disease (CKD). Assessing individual dietary salt intake is essential for promoting awareness of dietary salt reduction. We previously developed a dietary salt intake questionnaire that demonstrated high clinical utility because it identified the foods that contributed the most to an individual's salt intake. In this study, we developed a revised version of a self-administered dietary salt questionnaire based on data obtained from previous studies. We assessed the salt content of specific dishes and food groups and adjusted the estimated salt intake per meal based on body weight (BW), as dietary intake per meal differs depending on BW. In a multicenter study of 169 outpatients with CKD, the estimated dietary salt intake based on the revised questionnaire and previous salt intake questionnaires was compared with the daily salt intake calculated using a 24-h urine collection to evaluate their accuracy. Subgroup analyses were performed stratifying patients based on sex and age. The revised salt questionnaire showed a stronger correlation with 24-h urine collection (r = 0.43, p < 0.001) than the previous version (r = 0.36, p < 0.001). Subgroup analyses showed a stronger correlation in women (r = 0.47) than in men (r = 0.33) and in participants aged ≥65 years (r = 0.43) than in those aged <65 years (r = 0.35). In conclusion, it is important to improve the accuracy of dietary salt questionnaires and to establish their applicability for dietary salt guidance in clinical practice. This study contributes to the continuing efforts to improve the accuracy and clinical utility of dietary salt questionnaires.