H-type hypertension and risk of stroke in chinese adults: A prospective, nested case–control study

OBJECTIVES: To investigate the independent and joint associations of hyperhomocysteinemia and hypertension with incident stroke and stroke death in Chinese adults. METHODS: About 39,165 rural Chinese adults aged 35 years or older who had no history of stroke at the baseline study were prospectively followed to determine major cardiovascular events, with an average follow-up of 6.2 years. Using a nested case–control design, this report includes 179 incident stroke cases (121 stroke deaths) and 179 controls without vascular events from the original cohort matched by age, sex, community, and length of plasma storage. Baseline plasma total homocysteine (tHcy) measurements were obtained for all subjects. Logistic regression analysis was performed to investigate the independent and joint associations between H-type hypertension, defined as subjects with concomitant hypertension and elevated homocysteine (≥10 μmol/L), and risk of incident stroke and stroke death, after adjusting for important covariates. RESULTS: We analyzed each risk factor independently and jointly. For analysis, homocysteine was divided into three groups: low (tHcy <10 μmol/L), moderate (≥10 μmol/L tHcy <20 μmol/L), and high (tHcy≥20μmol/L). Compared to subjects in the low group, the odds ratios (95% CI) of incident stroke for those in the moderate group and the high group were 1.7 (0.8–3.7) and 3.1 (1.2–8.6), respectively. The odds ratios (95% CI) of stroke death for the moderate and high groups were 2.8 (1.1–7.4) and 5.1 (1.6–16.4), respectively. Hypertension was also independently associated with a higher risk of incident stroke and stroke death: 3.8 (2.3–6.4) and 3.2 (1.8–6.0), respectively, compared to those without hypertension. When analyzed jointly, the highest risk was found among patients with H-type hypertensive with both hyperhomocysteinemia and hypertension: 12.7 (2.8–58.0) for incident stroke and 11.7 (2.5–54.7) for stroke death. CONCLUSIONS: This study provides strong evidence that hyperhomocysteinemia and hypertension are two independent, modifiable risk factors, which act additively to increase the risk of incident stroke and stroke death. The results strongly suggest that H-type hypertension is a major risk factor for vascular disease and mortality, and those with H-type hypertension may particularly benefit from homocysteine-lowering therapy along with anti-hypertension therapy in Chinese populations.