Demographic associations of high estimated sodium intake and frequency of consumption of high-sodium foods in people with chronic kidney disease stage 3 in England.

OBJECTIVE

The objective of this study was to investigate sodium intake in a cohort of people with chronic kidney disease (CKD) Stage 3 in England to identify demographic characteristics of subgroups with high sodium intake and specific foods that contribute to excessive sodium intake.

DESIGN AND

METHODS

Study subjects (N = 1,729) included CKD patients from 32 general practices in the Renal Risk in Derby study. Patients had a glomerular filtration rate between 30 and 59 mL/min per 1.73 m(2) on 2 or more occasions at least 3 months apart before recruitment. Sodium excretion (assumed to be equal to intake) was estimated from early morning urine specimens using an equation validated for this study population. The frequency of intake of 12 salty foods was assessed by a food frequency questionnaire.

RESULTS

The mean estimated urinary sodium excretion was 110.5 ± 33.8 mmol/day; 60.1% had values above the National Kidney Foundation recommendation (<100 mmol/day). Subgroups with a greater percentage of participants having sodium excretion above the recommendation were as follows: men, those younger than 75 years of age, those with central obesity or diabetes, those with formal educational qualifications, and those who were previous or current smokers. In multivariable analysis, gender, younger age, waist-to-hip ratio, and diabetes mellitus status were the main independent determinants of excessive sodium excretion. Specific food items that contributed to excessive intake were table and cooking salt, salted snacks, hard cheeses, processed meat, and tinned fish. The most important source of sodium varied by subgroup.

CONCLUSION

A high prevalence of sodium excretion above the recommended value was detected, and independent determinants were gender, age, waist-to-hip ratio, and diabetes mellitus. Specific food items that contributed to excessive intake were also identified and varied in different subgroups. These data will be helpful in informing strategies to target dietetic advice to those most likely to have high sodium intake and will allow dietitians to focus on the most likely sources of sodium in different subgroups.