The effect of sodium restriction and weight reduction on blood pressure of patients with hypertension and chronic renal disease

Abstract

Objective: To examine the blood pressure (BP) effect of sodium intake and weight changes in hypertensive patients with moderate to advanced chronic renal diseases. Design: Subgroup analyses comparing urine, sodium, weight, and BP changes by lifestyle modification (sodium, weight, sodium and weight, or none). Setting: 15 US clinical centers Patients: 724 hypertensive patients with chronic renal disease used in the Modification of Diet in Renal Disease (MDRD) Study Group. Interventions: Primary MDRD interventions were protein and phosphorus reductions in the diet and hypertension treatment with antihypertensive medications. Secondary interventions included lifestyle modifications. Main outcome measures: BP changes during 18 months of follow-up. Results: In this study, 51.2% of patients were prescribed sodium or weight modifications: sodium or sodium plus weight loss (31.2%) and weight alone (20.0%). After 18 months, sodium reductions averaged 4.3 mmol/L in the usual mean arterial pressure (MAP) group and 20.7 mmol/L in the low MAP group. Weight reductions averaged 2.0 kg in the usual MAP group and 1.4 kg in the low MAP group. BP decreased more in low MAP patients advised to reduce sodium or weight (−4.5 to −5.7 mm Hg; P = .0002), and patients on both weight and sodium modifications showed the largest decrease. Multiple regression analyses revealed significant association between weight change and BP in low MAP patients. Cautious interpretation is recommended because these were subgroup analyses and participants were not randomly assigned to lifestyle modifications. Conclusion: Planned weight loss and modest sodium reductions were observed in hypertensive MDRD Study participants on concurrent dietary protein and phosphorus and antihypertensive medication interventions. Sodium or weight benefits were greater in hypertensives randomized to low MAP and low protein goals. Even modest weight loss appeared beneficial for BP management. Weight loss benefits to blood pressure management would be important to confirm in future randomized studies of hypertensive renal patients.