Cardiovascular (CV) disease is a major health problem accounting for 17.5 million deaths worldwide each year. Accumulating evidence indicates that high potassium intake decreases blood pressure, independent of sodium intake. Moreover, recent analyses have suggested a protective effect of potassium intake on CV and renal disease. In this retrospective cohort study, performed in the outpatient clinic, we investigated the associations of potassium intake with CV and renal outcomes using multiple potassium measurement during 15 years of follow-up.
Design and method:
We selected all adult patients who visited the outpatient clinic of a Dutch tertiary hospital between 1998 and 1999, and collected at least one 24-hour urine sample. Patients with an eGFR <60 ml/min were excluded. To accurately estimate potassium intake, we gathered data from all 24-hour urine samples collected during 15-year follow-up. All subjects were divided in tertiles according to their 15-year average 24-hour potassium excretion. We used Cox regression analysis with adjustment for CV risk factors to compare CV and renal outcome among tertiles. The primary outcome was a composite of all-cause mortality, CV (i.e. myocardial infarction, hospitalization for heart failure and cerebrovascular events) and renal events (i.e. 60% eGFR decline or need for persistent renal replacement therapy (RRT)).
We included 901 patients with a mean (±SD) age of 48 ± 14 year and a mean eGFR of 101 ± 27 ml/min. During a median follow up of 12.7 years, we collected 8,053 urine samples and a total of 258 events occurred. High potassium intake was not related to a higher risk for the primary endpoint or cardiovascular events (Table). Regarding renal endpoints, high potassium intake was associated with a lower risk of a 60% eGFR decline and RRT.
This study performed in the outpatient setting shows that high potassium intake is associated with renoprotection. However, this study was not able to prove a similar relation for CV disease and mortality. Dietary intervention studies directed to potassium intake on long-term renal and CV outcomes are warranted.