Chao Qiang Jiang

Reliability and validity of the IPAQ-Chinese: the Guangzhou Biobank Cohort study.

INTRODUCTION Valid measurements of self-reported physical activity are very limited in Chinese populations, especially the elderly. Therefore, we examined the validity and reliability of the Chinese version of the International Physical Activity Questionnaire (IPAQ-C) in older Chinese people. METHODS Two hundred twenty-four older adults (66.1% women, 33.9% men, mean age 65.2 +/- 5.7 yr) were randomly selected from the Guangzhou Biobank Cohort Study, a prospective cohort of older Chinese in Southern China. To examine the test-retest reliability, the participants completed the IPAQ-C twice during a 7-d interval. The criterion validity of the IPAQ-C was tested with pedometry. RESULTS Good reliability was observed between the repeated IPAQ-C, with intraclass correlation coefficients (ICC) ranging from 0.81 to 0.89. Total activity measured by IPAQ-C correlated moderately with the pedometer-measured steps (partial r = 0.33 adjusted for sex, age, and education; P < 0.001). The walking domain of IPAQ-C was strongly associated with the number of steps (partial r = 0.58, P < 0.001), but there were no significant associations between other activity domains of the IPAQ-C and the pedometer data. CONCLUSION This is the first reported validation study of an international standardized questionnaire (IPAQ-C) in older Chinese adults. Our study shows that the IPAQ-C is adequately valid and reliable for assessing total physical activity and that it may be a useful instrument for generating internationally comparable data on physical activity in this population.

Age of menarche and the metabolic syndrome in China.

Objectives: In western populations, young age of menarche is associated with increased cardiovascular risk. Little is known about the potential impact of menarche on the metabolic syndrome (as a proxy for cardiovascular risk) in rapidly economically developing populations where age of menarche is falling. We sought to determine the relation between age of menarche and the metabolic syndrome in a rapidly developing Chinese population. Methods: We carried out a retrospective historical cohort study of 7349 women from the Guangzhou Biobank Cohort Study, China, enrolled in 2003–2004. Cardiovascular risk factors were obtained from physical examination; age of menarche was obtained from self-report. The main outcome measure was the metabolic syndrome and its components. Results: Adjusted for age, education, and number of pregnancies, young age of menarche (<12.5 years) compared with age of menarche ≥14.5 years was associated with a higher risk of the metabolic syndrome (odds ratio = 1.49; 95% confidence interval = 1.22–1.82), central obesity (1.35; 1.10–1.65), raised blood pressure (1.34; 1.09–1.65), raised fasting glucose (1.40; 1.15–1.71), and higher triglyceride levels (1.36; 1.12–1.67). Further adjustment by waist circumference attenuated these effects, but the odds ratios remained elevated. Conclusions: Earlier age of menarche experienced by younger women in China today, now 12.5 years on average in urban populations, may contribute to an increase in the metabolic syndrome and thereby an increase in cardiovascular disease as these women age. These results further highlight the importance of childhood antecedents of adulthood disease.

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

BACKGROUND Prior 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. METHODS Participants 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. RESULTS The 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. CONCLUSIONS Prior 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.

Lymphocyte DNA damage in cigarette factory workers measured by the Comet assay

To investigate whether there were separate and combined effects of occupational exposure to tobacco dust and smoking on lymphocyte DNA damage, 148 workers from a cigarette manufacturing factory (107 occupationally exposed to tobacco dust from the production department and 41 unexposed controls who were managerial workers) were included in the study. The Tail Moment (TM) of Comet assay was used to measure DNA damage. The two groups had similar mean age, mean duration of work and smoking prevalence. The exposed workers had a larger TM than that of the controls (mean+/-S.D.: 43.43+/-13. 77 vs. 38.89+/-8.98, p<0.05). Smokers had significantly larger TM than non-smokers (47.25+/-14.02 vs. 38.90+/-10.75, p<0.001). Analysis of variance after adjustment for age and gender showed that occupational exposure and smoking had a significant and independent effect on Tail Moment (p=0.025 and p=0.002, respectively) and there was a significant positive two way interaction between the two factors (p=0.019). Age and gender had no significant effect on TM. The present study suggests that smoking and tobacco dust exposure can induce lymphocyte DNA damage and there is a synergistic effect of tobacco dust exposure and smoking on DNA damage.

Social mixing patterns in rural and urban areas of southern China

A dense population, global connectivity and frequent human–animal interaction give southern China an important role in the spread and emergence of infectious disease. However, patterns of person-to-person contact relevant to the spread of directly transmitted infections such as influenza remain poorly quantified in the region. We conducted a household-based survey of travel and contact patterns among urban and rural populations of Guangdong, China. We measured the character and distance from home of social encounters made by 1821 individuals. Most individuals reported 5–10 h of contact with around 10 individuals each day; however, both distributions have long tails. The distribution of distance from home at which contacts were made is similar: most were within a kilometre of the participants home, while some occurred further than 500 km away. Compared with younger individuals, older individuals made fewer contacts which tended to be closer to home. There was strong assortativity in age-based contact rates. We found no difference between the total number or duration of contacts between urban and rural participants, but urban participants tended to make contacts closer to home. These results can improve mathematical models of infectious disease emergence, spread and control in southern China and throughout the region.

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

BACKGROUND Prior 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. METHODS Participants 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. RESULTS The 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. CONCLUSIONS Prior 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

AIMS Smoking 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. METHODS This 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. RESULTS After 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). CONCLUSIONS Smoking 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.

Estimating the Life Course of Influenza A(H3N2) Antibody Responses from Cross-Sectional Data

The immunity of a host population against specific influenza A strains can influence a number of important biological processes, from the emergence of new virus strains to the effectiveness of vaccination programmes. However, the development of an individual’s long-lived antibody response to influenza A over the course of a lifetime remains poorly understood. Accurately describing this immunological process requires a fundamental understanding of how the mechanisms of boosting and cross-reactivity respond to repeated infections. Establishing the contribution of such mechanisms to antibody titres remains challenging because the aggregate effect of immune responses over a lifetime are rarely observed directly. To uncover the aggregate effect of multiple influenza infections, we developed a mechanistic model capturing both past infections and subsequent antibody responses. We estimated parameters of the model using cross-sectional antibody titres to nine different strains spanning 40 years of circulation of influenza A(H3N2) in southern China. We found that “antigenic seniority” and quickly decaying cross-reactivity were important components of the immune response, suggesting that the order in which individuals were infected with influenza strains shaped observed neutralisation titres to a particular virus. We also obtained estimates of the frequency and age distribution of influenza infection, which indicate that although infections became less frequent as individuals progressed through childhood and young adulthood, they occurred at similar rates for individuals above age 30 y. By establishing what are likely to be important mechanisms driving epochal trends in population immunity, we also identified key directions for future studies. In particular, our results highlight the need for longitudinal samples that are tested against multiple historical strains. This could lead to a better understanding of how, over the course of a lifetime, fast, transient antibody dynamics combine with the longer-term immune responses considered here.

Height, Its Components, and Cardiovascular Risk Among Older Chinese: A Cross-Sectional Analysis of the Guangzhou Biobank Cohort Study

OBJECTIVES Better childhood conditions, inferred from height and specifically leg length, are usually protective against ischemic heart disease and its risk factors in Western countries. In other geoethnic populations, height is less clearly protective, casting doubt on there being a biological etiology. To clarify the role of childhood conditions, we examined the associations of height and its components with cardiovascular risk among older Chinese people. METHODS We used multivariable regression to examine the associations of height and its components with blood pressure, lipid profile, and diabetes in 10413 older Chinese adults (mean age=64.6 years). RESULTS After we adjusted for age, gender, socioeconomic status, and lifestyle habits, greater sitting height was associated with diabetes and dyslipidemia. Longer legs were associated with lower pulse pressure and lower low-density lipoprotein cholesterol. CONCLUSIONS We provide indirect anthropometric evidence for the role of pre-pubertal and pubertal exposures on cardiovascular risk. Pubertal exposures are stronger than are prepubertal exposures but may be influenced by osteoporotic decline in old age. Further research should establish whether the observed relations are ethnically specific or relate to the stage or trajectory of socioeconomic development.