Sodium Intake from Various Time Frames and Incident Hypertension Among Chinese Adults

Background: Although it is clear that there are short-term effects of sodium intake on blood pressure, little is known about the most relevant timing of sodium exposure for the onset of hypertension. This question can be addressed only in cohorts with repeated measures of sodium intake. Methods: Using up to seven measures of dietary sodium intake and blood pressure between 1991 and 2009, we compared the association of baseline, mean, and most recent sodium intake with incident hypertension, in 6578 adults enrolled in the China Health and Nutrition Survey (age 18 to 65 years and free of hypertension at baseline). We used survival methods that account for the interval-censored nature of this study and inverse-probability weights to generate adjusted survival curves and time-specific cumulative risk differences; hazard ratios were also estimated. Results: Baseline sodium intake was not associated with incident hypertension. For the mean and most recent measures, the probability of hypertension-free survival was the lowest among those with the highest sodium intake compared with all other intake groups across the entire follow-up. In addition, the most recent sodium intake had a positive dose-response association with incident hypertension (risk difference at 11 years of follow-up = 0.04 [95% confidence interval = 0.00 to 0.08], 0.06 [0.02 to 0.11], 0.18 [0.12 to 0.24], and 0.20 [0.12 to 0.27] for the second to fifth sodium-intake groups compared with the lowest group, respectively). Conclusion: We found that, among the various time frames, the most recent exposure to sodium was most strongly associated with incident hypertension. (Epidemiology 2013; 24: 410-418)