Reduction in sodium intake is independently associated with improved blood pressure control in people with chronic kidney disease in primary care

Abstract

AbstractDecreasing sodium intake has been associated with improvements in blood pressure (BP) and proteinuria, two important risk factors for CVD and chronic kidney disease (CKD) progression. We aimed to investigate the role of sodium intake by examining the effect of changes in sodium intake over 1 year on BP and proteinuria in people with early stage CKD. From thirty-two general practices, 1607 patients with previous estimated glomerular filtration rate of 59–30 ml/min per 1·73 m2 and mean age of 72·9 (sd 9·0) years were recruited. Clinical assessment, urine and serum biochemistry testing were performed at baseline and after 1 year. Sodium intake was estimated from early morning urine specimens using an equation validated for this study population. We found that compared with people who increased their sodium intake from ≤100 to >100 mmol/d over 1 year, people who decreased their intake from >100 to ≤100 mmol/d evidenced a greater decrease in all BP variables (Δmean arterial pressure (ΔMAP)=–7·44 (sd 10·1) v. –0·23 (sd 10·4) mmHg; P<0·001) as well as in pulse wave velocity (ΔPWV=–0·47 (sd 1·3) v. 0·08 (sd 1·88) m/s; P<0·05). Albuminuria improved only in albuminuric patients who decreased their sodium intake. BP improved in people who maintained low sodium intake at both times and in those with persistent high intake, but the number of anti-hypertensive increased only in the higher sodium intake group, and PWV improved only in participants with lower sodium intake. Decreasing sodium intake was an independent determinant of ΔMAP. Although more evidence is needed, our results support the benefits of reducing and maintaining sodium intake below 100 mmol/d (2·3–2·4 g/d) in people with early stages of CKD.