A FEASIBILITY STUDY FOR A TRIAL TESTING THE EFFECTS OF REDUCED-SODIUM SALT ON THE RISE IN BLOOD PRESSURE WITH AGE

Objective: Excessive sodium intake is associated with elevated blood pressure, a major risk factor for cardiovascular disease, and average blood pressure rises with age in almost every population across the globe. Lowering sodium intake by switching regular salt for reduced-sodium salt may attenuate the rise in blood pressure with age. Before exploring this hypothesis in a large-scale clinical trial, we conducted a pilot study to assess project feasibility in Nigeria. Design and method: The study was an unblinded, non-randomized feasibility study conducted in two rural Nigerian communities between March and May 2024. Participants 6 years and older without severe kidney disease or taking potassium-sparing diuretics or potassium supplements were recruited at the household level and provided with reduced-sodium salt (66% potassium chloride, 34% sodium chloride) to replace all regular salt for cooking and seasoning over two months. There were four study visits including registration, baseline, 1-month, and 2-month follow-up. Outcomes included recruitment rate, adherence and acceptability of the intervention, adherence to study procedures, and willingness to participate in a longer-term study. Results: 41 households (148 participants) were recruited over five days. The median participant age was 12.5 years (IQR 9-32 years), and 55% were female. Nine participants (6%) were lost to follow-up at 2-months but data for at least one participant was available for 39 (95%) households. Most (98%) of the scheduled follow-up visits were completed with all participants present providing all key data (three blood pressure measures at each visit, and a weight measurement and spot urine sample at baseline and 2-months). Adherence to and acceptability of the reduced-sodium salt intervention were high. At 2-months, 88% of participants reported replacing all regular salt with reduced-sodium salt, and most (94% and 93%) participants reported it was similar to or better than regular salt for taste and overall acceptability, respectively. All participants indicated a willingness to engage in a 4-year study. Conclusions: It is feasible to conduct a large-scale clinical trial in rural Nigeria testing the effects of reduced-sodium salt compared to regular salt on the rise in blood pressure with age.