Elevated blood concentration of homocysteine (Hcy) has been suggested as a modifiable, independent risk factor for coronary artery disease, stroke, and deep vein thrombosis. Prevalence of hyperhomocysteinemia and folic acid deficiency in China are significantly higher than those in Europe and USA. The investigators' preliminary research demonstrated that blood concentration of Hcy was negatively correlated to estimated glomerular filtration rate (eGFR), a key index of kidney function. However, the question as to whether Hcy-lowering therapy with folic acid can reduce the risk of chronic kidney disease(CKD) remains to be answered.~This study, exploiting the hypertensive population of CSPPT trial (ClinicalTrials.gov register number: NCT00794885), is intended to compare the effects of enalapril maleate and folic acid tablets versus enalapril maleate in preventing renal function decline among the patients with primary hypertension. The results from this trial may have the potential to transform current clinical and public health findings into practice in the prevention of chronic kidney disease(CKD) in China.
The purpose of this trial is to confirm that enalapril maleate and folic acid tablets is more effective in preventing renal function decline among the patients with primary hypertension when compared to enalapril maleate.