Ta-Chen Su

Work Hours and Self-Reported Hypertension Among Working People in California

Among the risk factors for hypertension, stress, especially work stress, has drawn increasing attention. Another potential work-related risk factor for hypertension identified in the past few years is work hours. This article presents an analysis of work hours and self-reported hypertension among the working population in the state of California. The data set used for this study comes from the Public Use File of the 2001 California Health Interview Survey. The logistic regression analysis shows a positive association between hours worked per week and likelihood of having self-reported hypertension. Compared with those working between 11 and 39 hours per week, individuals working 40 hours per week were 14% (95% CI: 1.01 to 1.28) more likely to report hypertension, those who worked between 41 and 50 hours per week were 17% (95% CI: 1.04 to 1.33) more likely to report hypertension, and those who worked ≥51 hours per week were 29% (95% CI: 1.10 to 1.52) more likely to report hypertension after controlling for various potentially confounding variables, including demographic and biological risk factors and socioeconomic status. This analysis provides evidence of a positive association between work hours and hypertension in the California working population.

Chin-Shan Community Cardiovascular Cohort in Taiwan–baseline data and five-year follow-up morbidity and mortality

A cohort consisting of 3602 residents (82.8% of the target population) aged 35 years and older was established in 1990 in the Chin-Shan Community, a suburb 20 miles outside of metropolitan Taipei, Taiwan. The long-term objective was to investigate the prospective impact on cardiovascular health in a society undergoing transition from a developing to a developed nation. This article presents the study design, selected baseline risk factors of cardiovascular diseases (CVD), and CVD events at the 5-year follow-up evaluation with an emphasis on sociodemographic differences. The multivariate logistic regression analyses revealed that white-collar individuals were more likely than blue-collar workers to have dyslipidemia including high-density lipoprotein cholesterol (HDL-C) levels <35 mg/dl [odds ratio (OR) = 1.7, 95% confidence interval (CI) = 1.2-2.4] and low-density lipoprotein cholesterol (LDL-C) levels >/=160 mg/dl (OR = 1.3, 95% CI = 1.0-1.7). However, they were at slightly lower risk for stroke and CVD/sudden death, and at moderately higher risk for coronary artery disease and diabetes, although both these trends were not significant. Men were more likely than women to have HDL-C levels <35 mg/dl (OR = 1.8, 95% CI = 1.4-2.2), but they were less likely to have LDL-C levels >/=160 mg/dl (OR = 0.7, 95% CI = 0.6-0.8). The risk of CVD/sudden death was higher for men than for women during the follow-up period (OR = 1.9, 95% CI = 1.3-2.9). This could be due to risk factors such as a much higher prevalence of tobacco (61.9% vs. 4.5%) and alcohol (43.7% vs. 6.4%) use in men. In conclusion, individuals of higher socioeconomic status have a higher prevalence of dyslipidemia but slightly lower 5-year incidence of CVD events.

Uric acid level as a risk marker for metabolic syndrome: A Chinese cohort study

OBJECTIVE Despite some epidemiologic research demonstrating a positive relationship between serum uric acid (SUA) levels and the prevalence of metabolic syndrome (MetS), prospective data on SUA as a predictor of MetS incidence are limited. METHODS The authors examined SUA as a risk marker for incident MetS in a prospective study of 3857 subjects who were free of MetS at baseline recruitment. Hyperuricemia was defined as SUA ≥7.7 mg/dL for men and ≥6.6 mg/dL for women. The MetS was defined according to a unified criteria set by several major organizations. RESULTS During a mean follow-up of 5.41 years, 476 participants developed MetS. A significantly stepwise increase in the incidence of MetS across tertiles of SUA was observed in the whole group (p for trend <0.001). Among women, this association was more robust than in men. After adjustment for age, variations of blood pressure, triglycerides, HDL-C, glucose, and waist circumference, females in the middle and upper tertiles of SUA had significantly higher risk of developing MetS when compared with subjects in the lowest tertile [adjusted-HR (95% CI) was 1.67 (1.12-2.49) and 3.18 (2.20-4.60), respectively; p for trend <0.001]. Overall, hyperuricemia was a significantly independent risk determinant for MetS in women, but it was a non-significant factor for MetS mediating waist circumference and serum triglycerides in men. CONCLUSION SUA concentration is more closely associated with MetS in females than in males. Future investigations are needed to explore the underlying mechanisms involved in the sex-related association between SUA concentration and MetS risk.

Effects of Particle Size Fractions on Reducing Heart Rate Variability in Cardiac and Hypertensive Patients

It is still unknown whether the associations between particulate matter (PM) and heart rate variability (HRV) differ by particle sizes with aerodynamic diameters between 0.3 μm and 1.0 μm (PM0.3–1.0), between 1.0 μm and 2.5 μm (PM1.0–2.5), and between 2.5 μm and 10 μm (PM2.5–10). We measured electrocardiographics and PM exposures in 10 patients with coronary heart disease and 16 patients with either prehypertension or hypertension. The outcome variables were standard deviation of all normal-to-normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), low frequency (LF; 0.04–0.15 Hz), high frequency (HF; 0.15–0.40 Hz), and LF:HF ratio for HRV. The pollution variables were mass concentrations of PM0.3–1.0, PM1.0–2.5, and PM2.5–10. We used linear mixed-effects models to examine the association between PM exposures and log10-transformed HRV indices, adjusting for key personal and environmental attributes. We found that PM0.3–1.0 exposures at 1- to 4-hr moving averages were associated with SDNN and r-MSSD in both cardiac and hypertensive patients. For an interquartile increase in PM0.3–1.0, there were 1.49–4.88% decreases in SDNN and 2.73–8.25% decreases in r-MSSD. PM0.3–1.0 exposures were also associated with decreases in LF and HF for hypertensive patients at 1- to 3-hr moving averages except for cardiac patients at moving averages of 2 or 3 hr. By contrast, we found that HRV was not associated with either PM1.0–2.5 or PM2.5–10. HRV reduction in susceptible population was associated with PM0.3–1.0 but was not associated with either PM1.0–2.5 or PM2.5–10.

Does Hepatitis C Virus Infection Increase Risk for Stroke? A Population-Based Cohort Study

Background The relationship between hepatitis C virus infection and risk of stroke remains inconsistent. This study evaluates the risk of stroke in association with chronic hepatitis C infection in a longitudinal population-based cohort. Methods We identified 4,094 adults newly diagnosed with hepatitis C infection in 2002–2004 from the Taiwan National Health Insurance Research Database. Comparison group consisted of 16,376 adults without hepatitis C infection randomly selected from the same dataset, frequency matched by age and sex. Events of stroke from 2002–2008 were ascertained from medical claims (International Classification of Diseases, Ninth Revision, Clinical Modification, ICD-9-CM, codes 430–438). Multivariate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for potential associated factors including HCV infection, age, sex, low-income status, urbanization, cessation of cigarette smoking, alcohol-related illness, obesity, history of chronic diseases and medication use. Findings During 96,752 person-years of follow-up, there were 1981 newly diagnosed stroke cases. The HRs of stroke associated with medical conditions such as hypertension, diabetes and heart disease were 1.48 (95% CI 1.33 to 1.65), 1.23 (95% CI 1.11 to 1.36) and 1.17 (95% CI 1.06 to 1.30), respectively, after adjustment for covariates. The cumulative risk of stroke for people with hepatitis C and without hepatitis C infections was 2.5% and 1.9%, respectively (p<0.0001). Compared with people without hepatitis C infection, the adjusted HR of stroke was 1.27 (95% CI 1.14 to 1.41) for people with hepatitis C infection. Conclusion Chronic hepatitis C infection increases stroke risk and should be considered an important and independent risk factor.

Apolipoprotein B and non-high density lipoprotein cholesterol and the risk of coronary heart disease in Chinese

The aim of our study was to compare apolipoprotein B (apoB), non-high density lipoprotein cholesterol (nonHDL-C), low density lipoprotein cholesterol (LDL-C), and other lipid markers as predictors of coronary heart disease (CHD) in Chinese. Overall, 122 individuals developed CHD during a median 13.6 years of follow-up in 3,568 adult participants from a community-based cohort. The multivariate relative risk of CHD in the highest quintile compared with the lowest quintile was 2.74 [95% confidence interval (CI), 1.45–5.19] for apoB, 1.98 (95% CI, 1.00–3.92) for nonHDL-C, and 1.86 (95% CI, 1.00–3.49) for LDL-C (all tests for trend, P < 0.05). ApoB also had the highest receiver operator characteristic curve area (0.63; 95% CI, 0.58–0.68) in predicting CHD. When apoB and nonHDL-C were mutually adjusted, only apoB was predictive; the relative risk was 2.80 (95% CI, 1.31–5.96; P = 0.001) compared with 1.09 (95% CI, 0.49–2.40; P = 0.75) for nonHDL-C. Compared with the lowest risk, participants with the highest apoB and total cholesterol/HDL-C had a 3-fold increased risk of developing CHD (relative risk = 3.21; 95% CI, 1.45–7.14). These data provide strong evidence that apoB concentration was a better predictor of CHD than other lipid markers in Chinese.

Effects of menopause on intraindividual changes in serum lipids, blood pressure, and body weight—the Chin-Shan community cardiovascular cohort study

In Taiwan, the Chin-Shan Community Cardiovascular Cohort (CCCC) was assessed prospectively to determine whether the changes in cardiovascular risk factors for women age 45--54 years are due to menopause. The average paired percentage changes that occurred between baseline (1990-1991) and follow-up (4 years later) in fasting serum lipids were compared in three groups of women including groups of 59 and 224 who were pre- and postmenopausal, respectively, and a group of 118 who had spontaneously stopped menstruating. Postmenopausal women had the least gain in body mass index (BMI), whereas, mainly premenopausal women had increased systolic blood pressure (P<0.05). All women had elevated total cholesterol (TC) levels, with the greatest elevation in women transitioning into menopause (P<0.001). Low-density lipoprotein cholesterol (LDL-C) levels increased before and during the transition to menopause, but decreased after menopause (P<0.01). Age had significant association with changes in TC, triglyceride (TG) and LDL-C levels, whereas BMI had significant association with changes in TG, LDL-C, and high-density lipoprotein cholesterol (HDL-C) levels (P<0.05). After controlling for age and BMI, only differences in TC remained significant, with the greatest gain in women who stopped menstruating (12.9%) followed by pre- (6.5%) and postmenopausal women (4.8%). Changes in both systolic and diastolic blood pressures, and TG and HDL-C levels were not significantly different, but HDL-C levels declined between 11.5 and 14.7% in all groups. This study suggests an unfavorable effect of menopause on lipid metabolism, especially on the TC level, which was predominantly elevated during the transition to menopause. The decline of HDL-C is of concern.

Circulating levels of markers of inflammation and endothelial activation are increased in men with chronic spinal cord injury.

BACKGROUND/PURPOSE Accelerated atherogenesis is often seen in individuals with chronic spinal cord injury (SCI). However, the mechanisms contributing to this phenomenon remain unclear. This study aimed to evaluate whether SCI per se is associated with a low-grade chronic inflammatory state and endothelial activation, both of which are well-documented prerequisites for atherogenesis. METHODS Serum levels of markers of inflammation (C-reactive protein [CRP], interleukin-6, and soluble CD40 ligand) and endothelial activation (endothelin-1, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 [sVCAM-1]) were measured in SCI patients with CRP levels < 10 mg/L and with no evidence of active infection. Sixty-two men with traumatic neurologically complete SCI (20 tetraplegics and 42 paraplegics) and 29 age-matched male controls were enrolled. RESULTS Compared with able-bodied controls, subjects with SCI had a significantly lower body mass index (BMI) (-7%) and significantly lower serum levels of albumin (-10%), creatinine (-20%), low-density lipoprotein cholesterol (-10%), and high-density lipoprotein (HDL) cholesterol (-25%), and showed a trend toward higher fasting insulin levels. Irrespective of injury level and duration, subjects with SCI had significantly higher serum levels, compared to able-bodied controls, of CRP (mean, 4.0 +/- 2.7 mg/L vs. 1.4 +/- 1.1 mg/L), interleukin-6 (median, 2.5 pg/mL vs. 0.4 pg/mL; range, 1.5-3.6 pg/mL vs. 0.2-0.5 pg/mL), endothelin-1 (mean, 1.3 +/- 0.4 pg/mL vs. 0.9 +/- 0.3 pg/mL), and sVCAM-1 (mean, 1170 +/- 318 ng/mL vs. 542 +/- 318 ng/mL). The serum levels of all four factors correlated negatively with levels of serum albumin, creatinine and HDL cholesterol, but not with BMI or fasting insulin levels. In multivariate analyses, SCI was the only factor that was independently associated with increased serum levels of CRP, interleukin-6, endothelin-1 and sVCAM-1 after adjustment for confounding factors such as serum albumin and creatinine levels and parameters of dyslipidemia and insulin resistance. CONCLUSION In this study, we have, for the first time, demonstrated that SCI per se is associated with a low-grade chronic inflammatory state and endothelial activation, which may partly explain the increased atherogenic risk in patients with long-standing SCI.

Evidence for improved control of hypertension in Taiwan: 1993-2002.

Objective This study reports the prevalence of hypertension, proportions of awareness, treatment, and control in the 2002 Taiwanese Survey on Hypertension, Hyperglycemia, and Hyperlipidemia (TwSHHH), and compared the changes of hypertension prevalence, awareness, treatment, and control in two recent nationwide surveys. Methods TwSHHH is the second nationwide survey designed to assess the prevalence, awareness, treatment, and control of hyperglycemia, hyperlipidemia, and hypertension. The TwSHHH survey applied a multistage, stratified, and random sampling during 2002 with a total of 7566 participants. Among them, 3088 male and 3391 female participants were 19 years old and over and were selected from households throughout Taiwan. The data of Nutrition and Health Survey in Taiwan (NAHSIT), the first nationwide survey to assess disease and nutrition status during 1993–1996, was also applied to compare changes of the prevalence, awareness, treatment, and control of hypertension between the two surveys. Results Compared with the NAHSIT, the prevalence of hypertension on TwSHHH decreased significantly in female adults, between 1993–1996 and 2002. In both males and females of all age groups, the awareness, treatment, and control of hypertension significantly and substantially improved between NAHSIT and TwSHHH. These results also correlated in time with the implementation of National Health Insurance since 1995. The favorable changes in education and availability of care may account for improved control of hypertension and, possibly, its prevention. Conclusions There was a significant improvement of hypertension awareness, treatment, and control in the TwSHHH survey compared with the NAHSIT survey in Taiwan.

Red Blood Cell Distribution Width and Risk of Cardiovascular Events and Mortality in a Community Cohort in Taiwan

The authors investigated whether red blood cell distribution width (RDW) was associated with the development of cardiovascular disease (CVD) events and mortality in a community cohort in Taiwan. The influence of anemia on the association was also assessed. RDW levels were measured in 3,226 participants aged 35 years or older who reported no CVD or cancer at baseline in 1990. During a median follow-up period of 15.9 years (1990-2007), 358 participants experienced stroke and/or coronary heart disease, and 810 participants died. The multivariate-adjusted hazard ratio for subjects in the highest RDW quartile as compared with the lowest quartile was 1.46 for both all-cause mortality (95% confidence interval: 1.17, 1.81) and non-CVD mortality (95% confidence interval: 1.13, 1.88) (P for trend < 0.01 for both) but was not significant for CVD morbidity and mortality. Further analyses showed that in comparison with participants with low RDW and no anemia, persons with high RDW but no anemia had elevated risks of all-cause mortality and non-CVD mortality. The authors conclude that elevated RDW values are associated with increased risk of mortality but not the development of CVD in the general population. RDW may precede anemia in predicting the risk of non-CVD death.