Effect of long-term low-dose folic acid supplementation on degree of total homocysteine-lowering: major effect modifiers.

We sought to examine the potential modifiers in the association between long-term low-dose folic acid supplementation and the reduction of serum total homocysteine (tHcy) among hypertensive patients, using data from the China Stroke Primary Prevention Trial (CSPPT). This analysis included 16 867 participants who had complete data on tHcy measurements at both the baseline and exit visit. After a median treatment period of 4·5 years, folic acid treatment significantly reduced the tHcy levels by 1·6 µmol/l (95 % CI 1·4, 1·8). More importantly, after adjustment for baseline tHcy and other important covariates, a greater degree of tHcy reduction was observed in certain subgroups: males, the methylenetetrahydrofolate reductase (MTHFR) 677TT genotype, higher baseline tHcy levels (≥12·5 (median) v. <12·5 µmol/l), lower folate levels (<8·0 (median) v. ≥8·0 ng/ml), estimated glomerular filtration rate (eGFR) <60 ml/min per 1·73 m2 (v. 60-<90 and ≥90 ml/min per 1·73 m2), ever smokers and concomitant use of diuretics (P for all interactions <0·05). The degree of tHcy reduction associated with long-term folic acid supplementation can be significantly affected by sex, MTHFR C677T genotypes, baseline folate, tHcy, eGFR levels and smoking status.

Homocysteine and Stroke Risk: Modifying Effect of Methylenetetrahydrofolate Reductase C677T Polymorphism and Folic Acid Intervention.

BACKGROUND AND PURPOSE: Elevated blood homocysteine concentration increases the risk of stroke, especially among hypertensive individuals. Homocysteine is largely affected by the methylenetetrahydrofolate reductase C677T polymorphism and folate status. Among hypertensive patients, we aimed to test the hypothesis that the association between homocysteine and stroke can be modified by the methylenetetrahydrofolate reductase C677T polymorphism and folic acid intervention. METHODS: We analyzed the data of 20 424 hypertensive adults enrolled in the China Stroke Primary Prevention Trial. The participants, first stratified by methylenetetrahydrofolate reductase genotype, were randomly assigned to receive double-blind treatments of 10-mg enalapril and 0.8-mg folic acid or 10-mg enalapril only. The participants were followed up for a median of 4.5 years. RESULTS: In the control group, baseline log-transformed homocysteine was associated with an increased risk of first stroke among participants with the CC/CT genotype (hazard ratio, 3.1; 1.1-9.2), but not among participants with the TT genotype (hazard ratio, 0.7; 0.2-2.1), indicating a significant gene-homocysteine interaction (P=0.008). In the folic acid intervention group, homocysteine showed no significant effect on stroke regardless of genotype. Consistently, folic acid intervention significantly reduced stroke risk in participants with CC/CT genotypes and high homocysteine levels (tertile 3; hazard ratio, 0.73; 0.55-0.97). CONCLUSIONS: In Chinese hypertensive patients, the effect of homocysteine on the first stroke was significantly modified by the methylenetetrahydrofolate reductase C677T genotype and folic acid supplementation. Such information may help to more precisely predict stroke risk and develop folic acid interventions tailored to individual genetic background and nutritional status. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885.

Folic acid therapy reduces serum uric acid in hypertensive patients: a substudy of the China Stroke Primary Prevention Trial (CSPPT).

Background: The effect of folic acid supplementation on uric acid (UA) concentrations is still inconclusive.Objective: We aimed to test the efficacy of folic acid therapy in reducing serum UA in hypertensive patients.Design: A total of 15,364 hypertensive patients were randomly assigned to a double-blind daily treatment with a single tablet that contained 10 mg enalapril and 0.8 mg folic acid (n = 7685) or 10 mg enalapril alone (n = 7679). The main outcome was the change in serum UA, which was defined as UA at the exit visit minus that at baseline. Secondary outcomes were as follows: 1) controlled hyperuricemia (UA concentration <357 µmol/L after treatment) and 2) new-onset hyperuricemia in participants with normal UA concentrations (<357 µmol/L).Results: After a median of 4.4 y of treatment, the mean ± SD UA concentration increased by 34.7 ± 72.5 µmol/L in the enalapril-alone group and by 30.7 ± 71.8 µmol/L in the enalapril-folic acid group, which resulted in a mean group difference of -4.0 µmol/L (95% CI: -6.5, -1.6 µmol/L; P = 0.001). Furthermore, compared with enalapril alone, enalapril-folic acid treatment showed an increase in controlled hyperuricemia (30.3% compared with 25.6%; OR: 1.31; 95% CI: 1.01, 1.70) and a decrease in new-onset hyperuricemia (15.0% compared with 16.3%; OR: 0.89; 95% CI: 0.79, 0.99). A greater beneficial effect was observed in subjects with hyperuricemia (P-interaction = 0.07) or higher concentrations of total homocysteine (tHcy) (P-interaction = 0.02) at baseline. Furthermore, there was a significant inverse relation (P < 0.001) between the reduction of tHcy and the change in UA concentrations.Conclusions: Enalapril-folic acid therapy, compared with enalapril alone, can significantly reduce the magnitude of the increase of UA concentrations in hypertensive adults. This trial was registered at clinicaltrials.gov as NCT00794885.

Folic Acid Therapy Reduces the First Stroke Risk Associated With Hypercholesterolemia Among Hypertensive Patients.

BACKGROUND AND PURPOSE: We sought to determine whether folic acid supplementation can independently reduce the risk of first stroke associated with elevated total cholesterol levels in a subanalysis using data from the CSPPT (China Stroke Primary Prevention Trial), a double-blind, randomized controlled trial. METHODS: A total of 20 702 hypertensive adults without a history of major cardiovascular disease were randomly assigned to a double-blind daily treatment of an enalapril 10-mg and a folic acid 0.8-mg tablet or an enalapril 10-mg tablet alone. The primary outcome was first stroke. RESULTS: The median treatment duration was 4.5 years. For participants not receiving folic acid treatment (enalapril-only group), high total cholesterol (≥200 mg/dL) was an independent predictor of first stroke when compared with low total cholesterol (<200 mg/dL; 4.0% versus 2.6%; hazard ratio, 1.52; 95% confidence interval, 1.18-1.97; P=0.001). Folic acid supplementation significantly reduced the risk of first stroke among participants with high total cholesterol (4.0% in the enalapril-only group versus 2.7% in the enalapril-folic acid group; hazard ratio, 0.69; 95% confidence interval, 0.56-0.84; P<0.001; number needed to treat, 78; 95% confidence interval, 52-158), independent of baseline folate levels and other important covariates. By contrast, among participants with low total cholesterol, the risk of stroke was 2.6% in the enalapril-only group versus 2.5% in the enalapril-folic acid group (hazard ratio, 1.00; 95% confidence interval, 0.75-1.30; P=0.982). The effect was greater among participants with elevated total cholesterol (P for interaction=0.024). CONCLUSIONS: Elevated total cholesterol levels may modify the benefits of folic acid therapy on first stroke. Folic acid supplementation reduced the risk of first stroke associated with elevated total cholesterol by 31% among hypertensive adults without a history of major cardiovascular diseases. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885.

Effect of folic acid supplementation on risk of new-onset diabetes in adults with hypertension in China: Findings from the China Stroke Primary Prevention Trial (CSPPT).

BACKGROUND: The aim of the present post hoc analysis of the China Stroke Primary Prevention Trial (CSPPT) was to evaluate the effect of folic acid supplementation on the risk of new-onset diabetes in hypertensive adults in China. METHODS: In all, 20 702 hypertensive adults with no history of stroke and/or myocardial infarction (MI) were randomly assigned to receive double-blind daily treatment with tablets containing either: (i) 10 mg enalapril and 0.8 mg folic acid (n = 10 348); or (ii) 10 mg enalapril alone (n = 10 354). New-onset diabetes was defined as either self-reported physician-diagnosed diabetes or the use of glucose-lowering drugs during the follow-up period of the CSPPT. RESULTS: Over a median treatment duration of 4.5 years, new-onset diabetes occurred in 198 (2.0%) and 214 (2.1%) subjects in the enalapril-folic acid and enalapril groups, respectively (hazard ratio [HR] 0.92; 95% confidence interval [CI] 0.76-1.12). Similar results were observed when analyses were limited to subjects with baseline fasting glucose (FG) <7.0 mmol/L (HR 0.85; 95% CI 0.62-1.14). Furthermore, there was no significant group difference in: (i) the risk of new-onset FG ≥7.0 mmol/L (defined as FG <7.0 at baseline and ≥7.0 mmol/L at the last visit; relative risk [RR] 1.07; 95% CI 0.96-1.20); or (ii) the composite of new-onset diabetes or new-onset FG ≥7.0 mmol/L (RR = 1.06; 95% CI 0.95-1.19). CONCLUSIONS: Among adults with hypertension with no history of stroke and/or MI in China, folic acid supplementation had no significant effect on the risk of new-onset diabetes.

Prevalence of hyperhomocysteinaemia and its major determinants in rural Chinese hypertensive patients aged 45-75 years.

We aimed to investigate the prevalence of hyperhomocysteinaemia (total plasma homocysteine (tHcy) ≥ 10 µmol/l) and its major determinants in rural Chinese hypertensive patients. A cross-sectional investigation was carried out in Lianyungang of Jiangsu province, China. This analysis included 13 946 hypertensive adults. The prevalence of hyperhomocysteinaemia was 51.6 % (42.7 % in women and 65.6 % in men). The OR of hyperhomocysteinaemia were 1.52 (95 % CI 1.39, 1.67) and 2.32 (95 % CI 2.07, 2.61) for participants aged 55-65 and 65-75 v. 45-55 years; 1.27 (95 % CI 1.18, 1.37) for participants with a BMI ≥ 25 v. < 25 kg/m²; 1.14 (95 % CI 1.06, 1.23) for participants with v. without antihypertensive treatment; 1.09 (95 % CI 1.00, 1.18) for residents inland v. coastal; 0.89 (95 % CI 0.82, 0.97) and 0.83 (95 % CI 0.74, 0.92) for participants with moderate and high v. low physical activity levels; 1.54 (95 % CI 1.41, 1.68) and 2.47 (95 % CI 2.17, 2.81) for participants with a glomerular filtration rate 60-90 and < 60 v. ≥ 90 ml/min per 1.73 m²; and 1.20 (95 % CI 1.07, 1.35) and 3.81 (95 % CI 3.33, 4.36) for participants with CT and TT v. CC genotype at methylenetetrahydrofolate reductase 677C>T polymorphism, respectively. Furthermore, higher tHcy concentrations were observed in smokers of both sexes (men: geometric mean 12.1 (interquartile range (IQR) 9.2-14.5) v. 11.9 (IQR 9.-14.) µmol/l, P= 0.005; women: geometric mean 10·3 (IQR 8.3-13.0) v. 9.6 (IQR 7.8-11.6) µmol/l, P= 0.010), and only in males with hypertension grade 3 (v. grade 1 or controlled blood pressure) (geometric mean 12.1 (IQR 9.2-14.4) v. 11.7 (IQR 9.2-14.0), P= 0.016) and in male non-drinkers (yes v. no) (geometric mean 12.3 (IQR 9.4-14.8) v. 11.7 (IQR 9.1-13.9), P= 0.014). In conclusion, there was a high prevalence of hyperhomocysteinaemia in Chinese hypertensive adults, particularly in the inlanders, who may benefit greatly from tHcy-lowering strategies, such as folic acid supplementation and lifestyle change.