Sodium Intake and Its Impact on Blood Pressure Among Hypertensive Patients in Some Areas of Guizhou Province

Abstract OBJECTIVE To evaluate current sodium intake patterns among patients with primary hypertension in specific regions of Guizhou Province and explore the relationship of sodium intake with blood pressure. METHODS A total of 2364 hypertensive patients who visited the hypertension outpatient department of Zunyi Medical University Affiliated Hospital from May 2016 to December 2024 and did not receive antihypertensive treatment or had self-discontinued such medication for over 1 month were selected as the research subjects. The age, sex, 24-hour urine sodium and potassium, ambulatory blood pressure, and other data were collected. Salt intake was estimated based on 24-hour urinary sodium excretion, and the participants were categorized into low-salt (<100 mmol/d, n = 609), moderate-salt (100–<200 mmol/d, n = 1,339), and high-salt (≥200 mmol/d, n = 416) groups, as well as quartile groups based on the salt intake. Univariate analysis of variance (ANOVA), multiple linear regression, and logistic regression were used to assess correlations between urinary sodium and blood pressure, as well as the risk of widened pulse pressure. RESULTS The average salt intake of the selected patients was (9.47 ± 4.51) g/d. The salt intake of males was higher than that of females (t = 7.573, P < 0.001). The urinary sodium excretion in the youth group was higher than that in the middle-aged group, the elderly group, and the elderly groups (F = 21.786, P < 0.001). The average salt intake in northern, central, western, and eastern Guizhou was more than 6 g/d, and the salt intake in northern Guizhou was higher than that in central Guizhou (F = 9.947, P< 0.05). The salt intake in middle- and high-altitude areas was higher than that in low-altitude areas (t = 2.314, P = 0.021). The 24-hour systolic blood pressure (24hMSP), 24-hour diastolic blood pressure (24hMDP), and 24-hour pulse pressure (24hMPP) were higher in the high-salt group (F = 30.922, 23.664, 11.310, all P < 0.05). 24hMSP, 24hMDP, and 24hMPP were positively correlated with 24-hour urinary sodium (r = 0.165, 0.151, 0.093, all P < 0.001). Multiple linear regression analysis showed that 24hMSP, 24hMDP, and 24 hMPP increased by 6.050, 3.337, and 2.713 mmHg, respectively, in the fourth quartile group compared with the first quartile group (all P < 0.001). Multivariate logistic regression analysis showed that, compared with the first quartile of 24-hour urinary sodium, the odds ratio (95% confidence interval [CI]) of 24hMPP ≥ 55 mmHg in the second to fourth quartiles were 1.386 (1.050–1.829), 1.511 (1.142–1.999), and 1.694 (1.270–2.259), respectively. The results of receiver-operating characteristic curve (ROC) showed that 24-hour urinary sodium, baseline model, and baseline model + 24-hour urinary sodium had certain predictive value for wide pulse pressure, with AUC of 0.536 (95% CI: 0.510–0.563, Z = 2.571, P = 0.008), 0.638 (95% CI: 0.612–0.665, Z = 9.857, P < 0.001) and 0.644 (95% CI: 0.617–0.670, Z = 10.286, P < 0.001), respectively, compared with the baseline model. The 24-hour urinary sodium + baseline model could not significantly improve the predictive value of wide pulse pressure (Z = 0.303, P > 0.05). Restricted cubic spline results showed that 24-hour urinary sodium was positively correlated with the risk of wide pulse pressure (total P < 0.05, nonlinear P > 0.05). CONCLUSIONS The average salt intake of hypertensive patients in Guizhou exceeds the standard of the World Health Organization, and there are differences in gender, age, region, and altitude. With the increase of salt intake, 24hMSP, 24hMDP, and 24hMPP increase, and the increase in 24-hour urinary sodium (salt intake) is an independent risk factor for wide pulse pressure in patients with essential hypertension.