Association between plasma copper levels and first stroke: a community-based nested case-control study.

BACKGROUND AND AIMS: Uncertainty remains regarding the association between the risk of stroke and plasma copper levels in population with copper mostly in normal range due to limited data. We examined the association between baseline plasma copper and risk of first stroke in Chinese community-dwelling population. METHODS: We conducted a nested case control study from 'H-type Hypertension and Stroke Prevention and Control Project'. A total of 1255 first stroke cases and 1255 controls matched for age, sex and study site were included in the analysis. Conditional logistic regression analyses were performed to evaluate the association between plasma copper and first stroke. RESULTS: The overall mean of copper was 15.90 (2.66) µmol/L. In total, 94.26% participants' copper concentration was in the normal range by Mayo Clinic laboratory reference values. Smoothing curve showed that the associations of plasma copper with first stroke and its subtypes were linear. Each standard deviation (SD) increment of plasma copper was independently and positively associated with risk of first stroke [odds ratio (OR): 1.17, 95% confidence interval (CI): 1.07-1.28]. The multivariable ORs with 95% CIs for total stroke, ischemic stroke and hemorrhagic stroke in the highest versus the lowest quartile of plasma copper were 1.49 (1.16-1.90; P-trend = 0.001), 1.46 (1.12-1.92; P-trend = 0.004) and 2.05 (0.95-4.38; P-trend = 0.050), respectively. CONCLUSIONS: Baseline plasma copper was positively associated with risk of first ischemic stroke in an approximately linear fashion among Chinese community population (80.32% hypertensives), although their copper levels were mostly within the normal range according to current reference values. Our findings warrant additional investigation.

Association between baseline brachial-ankle pulse wave velocity and short-term risk of first stroke among Chinese hypertensive adults.

Little information is available on the association between brachial-ankle pulse wave velocity (baPWV) and the risk of stroke in Chinese H-type hypertension patients. Therefore, our study aimed to assess this association between baseline baPWV and short-term risk of first stroke and to propose a cutoff value of baPWV that could predict near cerebrovascular events. A total of 9787 hypertension patients without preexisting stroke who underwent baPWV measurement were included. The primary end points were first symptomatic stroke. Secondary end points were first ischemic stroke and first hemorrhagic stroke. During a median follow-up of 20.8 months, there was a total of 138 first strokes including 123 first ischemic strokes and 15 first hemorrhagic strokes. When baPWV was categorized in quartiles, the higher risks of first stroke (HR = 1.52; 95% CI: 1.05-2.21) and first ischemic stroke (HR = 1.53; 95% CI: 1.03-2.26) were found in participants in quartile 4 (≥21.31 m/s), compared with those in quartile 1-3 (<21.31 m/s). In receiver operating characteristic curve analysis, the best cutoff value of baPWV that could predict first stroke was 21.43 m/s. Higher baPWV (≥21.43 m/s) was significantly associated with increased risk of first stroke (HR = 1.60; 95% CI: 1.10-2.32) and first ischemic stroke (HR = 1.60; 95% CI: 1.08-2.37). In conclusion, higher baPWV levels were associated with an increased risk of first stroke among Chinese H-type hypertensive patients. In addition, a cutoff value of 21.43 m/s of baPWV was proposed that could predict the next two years' cerebrovascular events.

Association between serum calcium levels and first stroke: A community-based nested case-control study.

Background: Evidence from epidemiologic studies has been limited and inconsistent regarding the role of serum calcium in stroke incidence risk. We aimed to evaluate the association between serum albumin-corrected calcium and the risk of the first stroke in the Chinese community-dwelling population. Methods: The study sample population was drawn from the "H-type Hypertension and Stroke Prevention and Control Project." Using a nested case-control study, a total of 1,255 first-stroke cases and 1,255 controls matched for age, sex, and village were included in the final data analysis. We measured the serum calcium by inductively coupled plasma mass spectrometry and assessed the associations between serum albumin-corrected calcium and first stroke using conditional logistic regression. Results: The overall mean (SD) serum albumin-corrected calcium was 8.9 (0.6) mg/dl. Compared with the middle tertile (8.7-9.1 mg/dl), the multivariate-adjusted odds ratios (95% CIs) of first total stroke associated with the lowest tertile and the highest tertile of serum albumin-corrected calcium were 1.37 (1.10, 1.70) and 1.30 (1.04, 1.62), respectively. Similar trends were observed for the first ischemic stroke. Consistently, restricted cubic spline showed a U-shaped association between serum albumin-corrected calcium and risk of total stroke and ischemic stroke. However, serum albumin-corrected calcium had no significant effect on first hemorrhagic stroke. No significant effect modification was observed in the subgroup analysis. Conclusions: Our results suggested a U-shaped association between serum calcium and first stroke; both low and high serum calcium levels were associated with an increased risk of the first stroke in the Chinese population.

Plasma 25-hydroxyvitamin D3 concentrations and incident risk of ischemic stroke in rural Chinese adults: New insight on ceiling effect.

OBJECTIVE: The aim of this study was to investigate the relationship between 25-hydroxyvitamin D3 (25[OH]D3) and ischemic stroke and its potential modifying factors in rural Chinese adults. METHODS: This nested case-control study was drawn from the H-type Hypertension and Stroke Prevention and Control Project, a community-based, prospective, observational study. Plasma 25(OH)D3 was measured by liquid chromatography with tandem quadrupole mass spectrometry. All stroke records came from the Chinese Center for Disease Control and Prevention. Multiple logistic regression models were used to evaluate the association between 25(OH)D3 and risk of ischemic stroke. RESULTS: We included 1079 participants with ischemic stroke and 1079 matched controls. Due to a non-linear relationship, the analyses were stratified by 25(OH)D3. For those with 25(OH)D3 < 20 ng/mL, there was a 15% reduction in the risk of ischemic stroke for each SD increment in 25(OH)D3 (odds ratio, 0.85; 95% confidence interval, 0.73-0.99). Compared with the lowest-tertile group, the risk of ischemic stroke decreased by 39% (odds ratio, 0.61; 95% confidence interval, 0.41-0.89) in the highest-tertile group. Furthermore, two effect modifiers were identified: diabetes and homocysteine level. Although participants with 25(OH)D3 ≥ 20 ng/mL had the lowest risk of ischemic stroke overall, there was no dose-response association within that range. CONCLUSIONS: An inverse dose-response association between 25(OH)D3 and incident risk of ischemic stroke in rural Chinese adults was only observed in those with 25(OH)D3 < 20 ng/mL, along with two effect modifiers. Higher levels of 25(OH)D3 did not confer additional benefit.

Sex difference in the association between plasma selenium and first stroke: a community-based nested case-control study.

BACKGROUND: To date, there is no clearly defined association between plasma selenium levels and first stroke. We aimed to investigate the association between baseline plasma selenium and first stroke risk in a community-based Chinese population. METHODS: Using a nested case-control study design, a total of 1255 first stroke cases and 1255 matched controls were analyzed. Participant plasma selenium concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS), and the association of plasma selenium with first stroke risk was estimated by conditional logistic regression models. RESULTS: Overall, a non-linear negative association between plasma selenium and first total stroke and first ischemic stroke risks was found in males but not in females. Compared with participants with lower selenium levels (tertile 1-2, < 94.1 ng/mL), participants with higher selenium levels (tertile 3, ≥ 94.1 ng/mL) had significantly lower risks of first total stroke (OR 0.63; 95% CI 0.48, 0.83) and first ischemic stroke (OR 0.61; 95% CI 0.45, 0.83) in males but not in females with first total stroke (OR 0.92; 95% CI 0.69, 1.22) and first ischemic stroke (OR 0.89; 95% CI 0.65, 1.22). Furthermore, a stronger association between plasma selenium and first total stroke was found in males with higher vitamin E levels (≥ 13.5 µg/mL vs. < 13.5 µg/mL P-interaction = 0.007). No significant association was observed between plasma selenium and first hemorrhagic stroke risk in either males or females. CONCLUSION: Our study indicated a significant, non-linear, negative association between plasma selenium and first stroke in males but not in females. TRIAL REGISTRATION: ChiCTR1800017274 .

High-Density Lipoprotein Cholesterol and the Risk of First Ischemic Stroke in a Chinese Hypertensive Population.

BACKGROUND AND PURPOSE: Elevated high-density lipoprotein cholesterol (HDL-C) levels have displayed protection against cardiovascular disease. However, the association between specific lipoprotein classes and first ischemic stroke (IS) has not been well defined, particularly in higher-risk hypertensive populations. Our study evaluated the associations of HDL-C with first IS in a Chinese hypertensive population. METHODS: The study population was obtained from a community-based cohort study of hypertension in Lianyungang and Rongcheng, China. A nested case-control design was used that included 2463 identified first IS cases and 2463 controls matched by age ± 1 year, sex, and region. RESULTS: After adjusting for potential confounders, HDL-C was inversely associated with first IS (adjusted odds ratio [aOR]: 0.91; 95% confidence interval [CI]: 0.85-0.98). HDL-C levels of at least 65.4 mg/dL displayed a significant protective effect for first IS (aOR: 0.82; 95% CI: 0.69-0.98). Conversely, adverse effects of first IS were observed for low-density lipoprotein cholesterol (LDL-C) levels ≥138.1 mg/dL (aOR: 1.20; 95% CI: 1.02-1.42) and triglyceride (TG) levels ≥140.8 mg/dL (aOR: 1.27; 95% CI: 1.09-1.49). The risk associations of LDL-C and TG with first IS were attenuated in the presence of high HDL-C (≥53.0 mg/dL); an increased risk of first IS was only found in the presence of low HDL-C (<53.0 mg/dL) when LDL-C (aOR: 1.66; 95% CI: 1.19-2.31) and TG (aOR: 1.47; 95% CI: 1.17-1.84) were combined with HDL-C for analysis. CONCLUSION: In this community-based Chinese hypertensive population, higher HDL-C was a significant protective factor of first IS. These data add to the evidence describing the relationship between lipids and IS and suggest that HDL-C maybe is a marker of IS risk in Chinses hypertensive population.

Achieving blood pressure control targets in hypertensive patients of rural China - a pilot randomized trial.

BACKGROUND: This study aimed to test the feasibility and titration methods used to achieve specific blood pressure (BP) control targets in hypertensive patients of rural China. METHODS: A randomized, controlled, open-label trial was conducted in Rongcheng, China. We enrolled 105 hypertensive participants aged over 60 years, and who had no history of stroke or cardiovascular disease. The patients were randomly assigned to one of three systolic-BP target groups: standard: 140 to < 150 mmHg; moderately intensive: 130 to < 140 mmHg; and intensive: < 130 mmHg. The patients were followed for 6 months. DISCUSSION: The optimal target for systolic blood pressure (SBP) lowering is still uncertain worldwide and such information is critically needed, especially in China. However, in China the rates of awareness, treatment and control are only 46.9%, 40.7%, and 15.3%, respectively. It is challenging to achieve BP control in the real world and it is very important to develop population-specific BP-control protocols that fully consider the population's characteristics, such as age, sex, socio-economic status, compliance with medication, education level, and lifestyle. This randomized trial showed the feasibility and safety of the titration protocol to achieve desirable SBP targets (< 150, < 140, and < 130 mmHg) in a sample of rural, Chinese hypertensive patients. The three BP target groups had similar baseline characteristics. After 6 months of treatment, the mean SBP measured at an office visit was 137.2 mmHg, 131.1 mmHg, and 124.2 mmHg, respectively, in the three groups. Home BP and central aortic BP measurements were also obtained. At 6 months, home BP measurements (2 h after drug administration) showed a mean SBP of 130.9 mmHg in the standard group, 124.9 mmHg in the moderately intensive group, and 119.7 mmHg in the intensive group. No serious adverse events were recorded over the 6-month study period. Rates of adverse events, including dry cough, palpitations, and arthralgia, were low and showed no significant differences between the three groups. This trial provided real-world experience and laid the foundation for a future, large-scale, BP target study. TRIAL REGISTRATION: Feasibility Study of the Intensive Systolic Blood Pressure Control; ClinicalTrials.gov, ID: NCT02817503. Registered retrospectively on 29 June 2016.