Diet or Additional Supplement to Increase Potassium Intake: Protocol For An Adaptive Clinical Trial

Abstract

Background High blood pressure is the leading cause of cardiovascular disease worldwide. The prevalence of high blood pressure is steadily rising, with the growing and ageing population. Many medicines are available to decrease blood pressures successfully, as well as many non-medical options, such as dietary changes and exercise. There is a marked preference amongst patients, reiterated in a Hypertension Canada report, for more research into methods for controlling blood pressure without medicines or to reduce the burden of taking many pills to control high blood pressure. Indeed, effective options do exist, especially with diet, specifically decreasing sodium and increasing potassium in diet. Current public health outreach mostly focusses on sodium intake, even as the potassium intake in diet remains low especially in the Western world. Excellent data exist in the published research reporting that increasing potassium intake, either as diet or even as supplements, reduces blood pressure and reduces risk of cardiovascular outcomes such as stroke. However, the advice most often provided is to ‘eat more fruits and vegetables’ which does not get translated into concrete change. Methods We propose to do a clinical trial in two stages, with an adaptive trial design. In the first stage, participants with high blood pressure and proven low potassium intake (measured on the basis of a 24 hour urine collection) will get individually tailored dietary advice, reinforced by weekly supportive phone/email support. If at 4 weeks, there has not been a desired increase in potassium intake, they will be prescribed an additional potassium supplement. Testing will be conducted again at 4 weeks post initiating the potassium supplement, to confirm the efficacy of the potassium supplement. Final measurements will be planned at 52 weeks to observe and measure the persistence of the effect of diet or additional supplement. Concurrent measurements of sodium intake, blood pressure, participant satisfaction, and safety measures will also be done. Discussion The results of the study would help determine the most effective method of increasing potassium intake, thus reducing blood pressure, need for blood pressure lowering medicines, at the same time potentially increasing participant satisfaction. The current guidelines recommend changes in diet, not supplement, to increase potassium intake, hence the two stage design will only add supplements if the most rigorous dietary advice does not work. Trial registration: This study has been registered on ClinicalTrials.gov identifier NCT03809884, registered on January 18, 2019. URL: https://clinicaltrials.gov/ct2/show/NCT03809884