Factors Influencing Low Sodium Intake in People with Non-Dialysis Dependent Chronic Kidney Disease.

Objective: To evaluate dietary sodium intake in people with chronic kidney disease (CKD) and identify contributing factors to low sodium intake by applying the Theory of Planned Behaviour (TPB) framework.

Design And Methods: Non-dialysed people with CKD completed a 24-hour urinary sodium excretion test and Scored Salt Questionnaire (SSQ). A survey including socio-demographic information, Brief Illness Perception Questionnaire, Short Sodium Knowledge Survey and Dietary Sodium Restriction Questionnaire based on TPB measured the factors contributing to dietary adherence.

Results: Sixty-three people [age: 71 (IQR: 64-77); 27% female] participated with 80% having high urinary sodium excretion [median: 134 mmol/day (111; 183)] but only 40% reported high sodium intake [SSQ score = 53 (39; 75)]. Overall sodium knowledge was high in 57% of participants although only 33% had seen a dietitian. There was a positive correlation between attitude towards a low-sodium diet and subjective norm (social expectations), r = 0.44, p < 0.01; urinary sodium and the extent of perceived consequences of CKD (r = 0.26, p < 0.05); and the extent to which willpower was perceived as a barrier to adherence to dietary sodium restriction (r = 0.27, p < 0.05). Multiple regression analysis revealed taste of low-salt foods (β = 8.9, p < 0.01) explained 26.4% of variance in dietary sodium intake (R  = 0.264, F(12, 34), p < 0.01).

Conclusion: TPB successfully identified barriers to follow a low-sodium diet in non-dialysed people with CKD. Taste preferences, willpower, meeting social expectations and disease concern were identified as key contributing factors to adherence.