Evaluation of plasma vitamin E and development of proteinuria in hypertensive patients

Background: The prospective relationship between plasma vitamin E levels and proteinuria remains uncertain. We aimed to evaluate the association between baseline plasma vitamin E levels and the development of proteinuria and examine any possible effect modifiers in patients with hypertension. Methods: This was a post hoc analysis of the renal sub-study of the China Stroke Primary Prevention Trial (CSPPT). In total, 780 participants with vitamin E measurements and without proteinuria at baseline were included in the current study. The study outcome was the development of proteinuria, defined as a urine dipstick reading of a trace or ≥ 1+ at the exit visit. Results: During a median follow-up duration of 4.4 years, the development of proteinuria occurred in 93 (11.9%) participants. Overall, there was an inverse relationship between plasma vitamin E and the development of proteinuria (per standard deviation [SD] increment; odds ratio [OR]: 0.73, 95% confidence interval [CI]: 0.55-0.96). Consistently, when plasma vitamin E was assessed as quartiles, lower risk of proteinuria development was found in participants in quartiles 2-4 (≥ 7.3 μg/mL; OR: 0.57, 95% CI: 0.34-0.96) compared to those in quartile 1. None of the variables, including sex, age, and body mass index, significantly modified the association between vitamin E and proteinuria development. Conclusion: There was a significant inverse association between plasma vitamin E levels and the development of proteinuria in patients with hypertension. The results were consistent among participants with different baseline characteristics.