Wei Sen Zhang

Prior TB, Smoking, and Airflow Obstruction: A Cross-Sectional Analysis of the Guangzhou Biobank Cohort Study

BACKGROUNDnPrior pulmonary TB has been shown to be associated with a higher risk of airflow obstruction, which is the hallmark of COPD, but whether smoking modifies this relationship is unclear. We investigated the relationships between prior TB, smoking, and airflow obstruction in a Chinese population sample.nnnMETHODSnParticipants in the Guangzhou Biobank Cohort Study underwent spirometry, chest radiography, and a structured interview on lifestyle and exposures. Prior TB was defined as the presence of radiologic evidence suggestive of inactive TB. Airflow obstruction was based on spirometric criteria.nnnRESULTSnThe prevalence of prior TB in this sample (N = 8,066, mean age: 61.9 years) was 24.2%. After controlling for sex, age, and smoking exposure, prior TB remained independently associated with an increased risk of airflow obstruction (odds ratio = 1.37; 95% CI, 1.13-1.67). Further adjustment for exposure to passive smoking, biomass fuel, and dust did not alter the relationship. Smoking did not modify the relationship between prior TB and airflow obstruction.nnnCONCLUSIONSnPrior TB is an independent risk factor for airflow obstruction, which may partly explain the higher prevalence of COPD in China. Clinicians should be aware of this long-term risk in individuals with prior TB, irrespective of smoking status, particularly in patients from countries with a high TB burden.

Self-Reported Long Total Sleep Duration Is Associated With Metabolic Syndrome The Guangzhou Biobank Cohort Study

OBJECTIVE To examine the association between total sleep duration and the prevalence of metabolic syndrome (MetSyn) in older Chinese. RESEARCH DESIGN AND METHODS Cross-sectional analysis of baseline data from the Guangzhou Biobank Cohort Study (GBCS) was performed. Participants (n = 29,333) were aged ≥50 years. Risk of MetSyn and its components were identified for self-reported total sleep duration. RESULTS Participants reporting long (≥9 h) and short (<6 h) total sleep duration had increased odds ratio (OR) of 1.18 (95% CI 1.07–1.30) and 1.14 (1.05–1.24) for the presence of MetSyn, respectively. The relationship remained in long sleepers (OR 1.21 [1.10–1.34]) but diminished in short sleepers (0.97 [0.88–1.06]) after full adjustment. CONCLUSIONS Long sleep duration was associated with greater risk of MetSyn in older Chinese. Confirmation through longitudinal studies is needed. The mechanisms mediating the link between long sleep duration and MetSyn require further investigation.

Original ResearchCOPDPrior TB, Smoking, and Airflow Obstruction: A Cross-Sectional Analysis of the Guangzhou Biobank Cohort Study

BACKGROUNDnPrior pulmonary TB has been shown to be associated with a higher risk of airflow obstruction, which is the hallmark of COPD, but whether smoking modifies this relationship is unclear. We investigated the relationships between prior TB, smoking, and airflow obstruction in a Chinese population sample.nnnMETHODSnParticipants in the Guangzhou Biobank Cohort Study underwent spirometry, chest radiography, and a structured interview on lifestyle and exposures. Prior TB was defined as the presence of radiologic evidence suggestive of inactive TB. Airflow obstruction was based on spirometric criteria.nnnRESULTSnThe prevalence of prior TB in this sample (N = 8,066, mean age: 61.9 years) was 24.2%. After controlling for sex, age, and smoking exposure, prior TB remained independently associated with an increased risk of airflow obstruction (odds ratio = 1.37; 95% CI, 1.13-1.67). Further adjustment for exposure to passive smoking, biomass fuel, and dust did not alter the relationship. Smoking did not modify the relationship between prior TB and airflow obstruction.nnnCONCLUSIONSnPrior TB is an independent risk factor for airflow obstruction, which may partly explain the higher prevalence of COPD in China. Clinicians should be aware of this long-term risk in individuals with prior TB, irrespective of smoking status, particularly in patients from countries with a high TB burden.

Smoking, smoking cessation and inflammatory markers in older Chinese men: The Guangzhou Biobank Cohort Study

AIMSnSmoking increases the risk of cardiovascular disease and inflammation plays a key role in the process of atherosclerosis. We therefore study the role of smoking and smoking cessation on the levels of inflammatory markers, C-reactive protein (CRP) and white blood cell (WBC) count, in older Chinese men.nnnMETHODSnThis cross-sectional analysis included 2999 men aged 50-85 years who received a medical check-up including measurement of fasting plasma vascular risk factors. Information on smoking status, socioeconomic and lifestyle factors was collected by standardized interview.nnnRESULTSnAfter adjustment for potential confounders, both CRP and WBC increased linearly across never, former and current smokers (both p<0.01). The odds ratios of elevated CRP and WBC (upper tertiles) were also increased across never, former and current smokers (both p<0.01). Dose-response relationships were observed among current smokers. Compared to current smokers, the odds ratios of elevated CRP and WBC and means of CRP and WBC declined with longer duration of smoking cessation (all p<0.01).nnnCONCLUSIONSnSmoking is associated with increased CRP and WBC levels, and smoking cessation is associated with the reduction of the increase, confirming the benefits of quitting. Inflammation may be a potential mechanism by which smoking promotes atherosclerotic disease.

Atrial fibrillation and obesity among older Chinese: The Guangzhou Biobank Cohort Study

BACKGROUNDnAtrial fibrillation (AF) is the most common form of arrhythmia, and its prevalence is increasing. Few studies have examined its association with obesity as defined by different criteria, particularly in developing countries. We investigated the association between atrial fibrillation (AF) and obesity indices among older Chinese.nnnMETHODSnWe conducted a community-based nested case control study using cross-sectional data of 5882 men and 14,548 women aged 50 or above from Phases I and II (September 2003 to May 2006) of the Guangzhou Biobank Cohort Study (GBCS). AF cases were identified by the 12-lead body surface electrocardiogram.nnnRESULTSn159 AF cases (65 men and 94 women) were identified from 19,964 participants with ECG records. 9249 participants with other abnormal ECG findings were excluded, resulting in a case control comparison on 159 AF cases and 10,369 controls. After multivariate adjustment, BMI (adjusted odds ratio (OR) 1.06 per kg/m(2), 95% confidence interval (CI)=1.01-1.11) and waist circumference (adjusted OR 1.02 per cm (1.00-1.04)) were significant risk factors. The adjusted OR per Z-score [(individual value-mean)/standard deviation] for BMI and waist circumference was 1.21 (1.03-1.41) and 1.18 (1.01-1.38) respectively.nnnCONCLUSIONSnThis is the first report showing that both general and central obesity are associated with increased risk of AF in an Eastern population with much lower level of obesity than in the West. As both AF and obesity are increasing in developing countries, the results should have important public health implications.

Inequality and inequity in access to health care and treatment for chronic conditions in China: the Guangzhou Biobank Cohort Study

Non-communicable diseases (NCDs) are a large and rapidly-growing problem in China and other middle-income countries. Clinical treatment of NCDs is long-term and expensive, so it may present particular problems for equality and horizontal equity (equal treatment for equal need) in access to health care, although little is known about this at present in low- and middle-income countries. To address this gap, and inform policy for a substantial proportion of the global population, we examined inequality and inequity in general health care utilization (doctor consultations and hospital admissions) and in treatment of chronic conditions (hypertension, hyperglycaemia and dyslipidaemia), in 30 499 Chinese adults aged ≥50 years from one of Chinas richest provinces, using the Guangzhou Biobank Cohort Study (2003-2008). We used concentration indices to test for inequality and inequity in utilization by household income per head. Inequality was decomposed to show the contributions of income, indicators of need for health care (age, sex, self-rated health, coronary heart disease risk and chronic obstructive pulmonary disease) and non-need factors (education, occupation, out-of-pocket health care payments and health insurance). We found inequality and inequity in treatment of chronic conditions but not in general health care utilization. Using more objective and specific measures of need for health care increased estimates of inequity for treatment of chronic conditions. Income and non-need factors (especially health insurance, education and occupation) made the largest contributions to inequality. Further work is needed on why access to treatment for chronic conditions in China is restricted for those on low incomes and how these inequities can be mitigated.

Uric acid levels, even in the normal range, are associated with increased cardiovascular risk: The Guangzhou Biobank Cohort Study

OBJECTIVEnTo examine the association between serum uric acid (UA) levels and cardiovascular risk factors in subjects without diabetes or hyperuricemia.nnnMETHODSn6172 women and 2662 men aged 50+ years without diabetes from Phase 1 of the Guangzhou Biobank Cohort Study were included. Data on personal history, physical examination and biochemical parameters were collected. Subjects were categorized by serum UA concentration, and the association between UA levels and cardiovascular risk factors was examined using generalized linear models.nnnRESULTSnIn both men and women with normouricemia (UA<420 μmol/l in men and <360 μmol/l in women), tertiles of UA levels were adversely associated with body mass index, waist circumference, waist-to-hip ratio, total- and HDL-cholesterol, apolipoprotein A1, systolic and diastolic blood pressures, pulse pressure, fasting plasma glucose and white blood cell count (P value for trend ranged from 0.04 to <0.001), and also consistently associated with metabolic disorders including obesity, hypertension, hypertension treatment, dyslipidemia, waist circumference increased since the age of 18 years and the metabolic syndrome (P value for trend ranged from 0.02 to <0.001).nnnCONCLUSIONnIncreasing UA levels, even in subjects with normouricemia and without diabetes, were associated with increasing prevalence of cardiovascular risk factors, suggesting that clinically dichotomous definition of hyperuricemia may be inadequate and high-normal value of UA may warn of metabolic disorders.

Impact of impaired fasting glucose and impaired glucose tolerance on arterial stiffness in an older Chinese population: the Guangzhou Biobank Cohort Study–CVD

The aim of the study was to compare the impact of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) on vascular function among older Chinese people. A random sample of 671 men and 603 women aged 50 to 85 years without known diabetes from the Guangzhou Biobank Study-CVD was examined in a cross-sectional study. Subjects with no previously confirmed or treated diabetes but with both fasting plasma glucose less than 5.6 mmol/L and 2-hour glucose from 7.8 to less than 11.0 mmol/L were classified as having isolated IGT, and those with no previously confirmed and treated diabetes but with both fasting plasma glucose from 5.6 to less than 7.0 mmol/L and 2-hour glucose less than 7.8 mmol/L were classified as having isolated IFG. A total of 11.0% of the men and 8.6% of the women had isolated IFG, and 17.7% of the men and 18.6% of the women had isolated IGT. The brachial-ankle pulse wave velocity and pulse pressure were increased in both the isolated IFG and isolated IGT subjects compared with the normoglycemia group (both Ps < .001). Compared with subjects with isolated IFG, those with isolated IGT appeared to have a higher age- and sex-adjusted brachial-ankle pulse wave velocity (1543 +/- 22 vs 1566 +/- 17, P = .07) and to be more insulin resistant (2-hour postload insulin: 54.2 +/- 2.13 vs 26.8 +/- 2.99 muU/mL, P < .001), had a worse lipid profile (apolipoprotein [apo] B: 1.07 +/- 0.02 vs 0.97 +/- 0.02 g/L, P < .001; apo B/apo A-1 ratio: 0.80 +/- 0.02 vs 0.69 +/- 0.02, P < .001), but had lower glycosylated hemoglobin levels (6.03% +/- 0.06% vs 5.86% +/- 0.04%, P < .001) (values are mean +/- SE). Subjects with isolated IGT had greater arterial stiffness, probably as a result of being more insulin resistant, with a worse lipid profile than those with isolated IFG. The sole use of fasting glucose level to identify prediabetic people would fail to identify a significant proportion of the at-risk population.

Brachial-ankle pulse wave velocity and cardiovascular risk factors in the non-diabetic and newly diagnosed diabetic Chinese: Guangzhou Biobank Cohort Study-CVD

Increased arterial stiffness is an important cause of cardiovascular disease (CVD). We examined determinants of arterial stiffness in subjects across strata of glycaemic status.

Smoking, smoking cessation and aortic arch calcification in older Chinese: the Guangzhou Biobank Cohort Study.

OBJECTIVEnTo study the association between smoking, smoking cessation and aortic arc calcification (AAC) in an older Chinese population.nnnMETHODSnA total of 3022 men and 7279 women aged 50-85 years were recruited and received a medical check-up including measurement of fasting plasma vascular risk factors. Two radiologists reviewed the posterior-anterior plain chest X-ray radiographs and assessed AAC together. Information on smoking status, socioeconomic and lifestyle factors was collected.nnnRESULTSnThe crude prevalence of AAC in men (38.58%) was lower than that in women (41.37%). The adjusted odds ratios of AAC increased significantly across never, ex- and current smokers in both genders. Dose-response relationships were observed among current smokers for smoking amount (cigarettes/day), smoking duration (years) and cigarette pack-years in both genders (all p<0.01). The odds ratios decreased significantly (p=0.018) with longer duration of quitting in light ex-smoking men (<23.5 pack-years) but showed no beneficial effect (p=0.72) for heavy ex-smokers (>or=23.5 pack-years).nnnCONCLUSIONnSmoking increased the risk of AAC in Chinese, while smoking cessation decreased the risk only in male light ex-smokers. Chest X-ray is a cheap and simple method to detect AAC, which should be an important warning signal for immediate smoking cessation.