Discriminatory performance of adiponectin and leptin in the identification of impaired glucose tolerance: The Guangzhou Biobank Cohort Study - Cardiovascular Disease Subcohort.

BACKGROUND: To evaluate the additional discriminatory performance of adiponectin, leptin, and their ratio in the identification of impaired glucose tolerance (IGT) in men and women without diabetes on top of conventional risk factors. METHODS & RESULTS: A total of 698 subjects underwent an oral glucose tolerance test (oGTT) and adipocytokine measurements. A comprehensive stepwise selection procedure was performed, followed by c-statistics and integrated discrimination improvement (IDI) analysis. In males, adiponectin levels were significantly lower in the IGT group compared to the non-IGT group (Whitney U test, p < 10-4), whereas leptin levels were significantly higher (p = 0.009) in IGT group. In females, adiponectin and leptin levels were not significantly different between groups (Mann-Whitney U test, p = 0.073 and p = 0.08, respectively). Adjusting for the most informative, sex-specific, clinical and biochemical factors, adiponectin, leptin and their ratio were not found to be significant predictors of the response to the glucose load, when modelled as continuous terms or tertiles. In males, the area-under-the-curve (AUC) for adiponectin was estimated at 0.620 (95% CI: 0.558-0.682) and the addition of adiponectin into the basic model provided a ΔAUC benefit of 0.004, showing no additional discriminatory benefit on top of conventional risk factors (IDI p-value: 0.27), nor did the addition of leptin or their ratio. The results were similar in females. CONCLUSIONS: In Chinese individuals without diabetes, no significant evidence for the potential discriminatory value of adiponectin, leptin or their ratio in the identification of IGT on top of conventional risk factors was observed.

Glycated Hemoglobin, Albuminuria and Surrogate Markers of Macrovascular Disease in Adults Without Diabetes: The Guangzhou Biobank Cohort Study, Cardiovascular Disease Subcohort.

OBJECTIVES: To explore the clinical utility of glycated hemoglobin (A1C) levels as an early marker of albuminuria, macrovascular disease and subclinical cardiovascular disease in comparison to fasting and postprandial glucose levels in a well-characterized Chinese population with no history of diabetes. METHODS: The study population consisted of 1223 individuals who were enrolled in the Guangzhou Biobank Cohort Study, Cardiovascular Disease Subcohort, and who had undergone oral glucose tolerance tests. The associations between each glycemic measure and albuminuria, carotid intima-media thickness (CIMT) and CIMT-based presence of carotid plaques and aortic arch calcification were assessed by chest radiographs. RESULTS: The overall prevalence of albuminuria, carotid plaque and any aortic arch calcification was 20.6%, 22.8% and 25.8%, respectively. All 3 glycemia indices were significantly associated with albuminuria, but only 1 (fasting glucose) was associated with carotid plaques. No significant difference was detected among them in the area under the curve for albuminuria (chi-square test; p=0.84), carotid plaques (p=0.28) or calcifications (p=0.29). In sensitivity analysis, adjusted for age and sex, the above findings remained unchanged. CONCLUSIONS: Although there was evidence suggesting differential associations, the performance of the glycemic indices was similar, and their association with macrovascular disease and albuminuria was modest.

Smoking and mortality in a prospective cohort study of elderly Chinese in Hong Kong.

BACKGROUND AND AIMS: Large cohort studies on smoking and mortality in elderly people are scarce, and few studies examined smokers aged 85+ years separately. We estimated the risks of all-cause and cause-specific mortality due to smoking in an elderly Chinese cohort in Hong Kong. DESIGN: A population-based prospective cohort of 65,510 Chinese enrolled from 1998 to 2001 and followed until May 2012. SETTING: All 18 Elderly Health Service centres in Hong Kong, China. PARTICIPANTS: Elderly people aged 65+ years. MEASUREMENTS: Self-reported smoking status was assessed at baseline interview and categorized as never, former and current smokers. FINDINGS: Compared with never smokers, after adjustment for sex, age, education, social security assistance, housing type, monthly expenditure, alcohol use, depressive symptoms and health status, the hazard ratio (HR) for current smokers was 1.89 [95% confidence interval (CI) = 1.81-1.98] for all participants aged 65+ years at baseline, corresponding to an attributable fraction (AF) of about 50%, which is based on AF = (HR-1)/HR. As the effect of smoking varied with age (P for age interaction <0.001), subgroup analysis by age group showed that the adjusted HR for current smokers aged 65-84 years was 1.93 (95% CI = 1.84-2.03), and for 85+ years was 1.29 (95% CI = 1.05-1.58). All the risk estimates did not vary by sex (P for sex interaction ranged 0.74-0.89). CONCLUSIONS: In Hong Kong, the risk of death from smoking appears to be the same for Chinese women as it is for men. Half of all deaths in Chinese smokers aged 65 years and older and a quarter of all deaths in Chinese smokers aged 85 years and older are caused by smoking-attributable diseases.

Sex disparities in risk and risk factors for ischemic heart disease in the Asia-Pacific region.

BACKGROUND: Ischemic heart disease (IHD) is the leading cause of death and disability worldwide, with higher rates among men than women. Relatively few studies on risk factor associations are available from the Asia-Pacific region, especially with regard to sex differences. Our objective was to compare the relationships between modifiable risk factors and IHD in men and women from the Asia-Pacific region. METHODS: Data from 600,445 individuals from 44 studies from the Asia Pacific Cohort Studies Collaboration, an individual patient data overview, were used. Cox models were used to evaluate the effects of risk factors on fatal and non-fatal IHD separately in men and women from Australia and New Zealand (ANZ) and Asia. RESULTS: Over a median follow-up of 6.7 years, 5695 IHD events were documented. The hazard ratio for IHD, comparing men with women, was 2.14 (95% CI 1.97-2.33) in ANZ and 1.88 (95% CI 1.54-2.29) in Asia. The age-adjusted prevalence of major risk factors was generally higher in men than women, especially in ANZ. Risk factors acted broadly similarly between men and women in both Asia and ANZ, with any indications of differences tending to favor men, rather than women. CONCLUSION: The excess risk of IHD observed in men compared with women in both Asia and ANZ may be, at least in part, a result of a more hazardous risk profile in men compared with women. The contribution of sex differences in the magnitude of the risk factor-disease associations is unlikely to be a contributing factor.

Cigarette smoking as a risk factor for influenza-associated mortality: evidence from an elderly cohort.

BACKGROUND: The effects of individual lifestyle factors on the mortality risk after influenza infection have not been explored. OBJECTIVES: In this study, we assessed the modifying effects of cigarette smoking on mortality risks associated with influenza in a cohort of Hong Kong elders with a follow-up period of 1998-2009. METHODS: We used the Cox proportional hazards model with time-dependent covariates of weekly proportions of specimens positive for influenza (termed as influenza virus activity), to calculate the hazard ratio of mortality associated with a 10% increase in influenza virus activity for never, ex- and current smokers. Other individual lifestyle and socioeconomic factors as well as seasonal confounders were also added into the models. RESULTS: The overall hazard ratio associated with influenza was 1·028 (95% confidence interval, 1·006, 1·051) for all natural cause mortality and 1·035 (1·003, 1·068) for cardiovascular and respiratory mortality. We found that influenza-associated hazard ratio was greater in current and ex-smokers than in never smokers for mortality of all natural causes, cardiovascular and respiratory diseases. CONCLUSIONS: The findings suggest that smoking might increase influenza-associated mortality risks among elders.

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 China's 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.

Life-course origins of social inequalities in adult immune cell markers of inflammation in a developing southern Chinese population: the Guangzhou Biobank Cohort Study.

BACKGROUND: Socioeconomic position (SEP) throughout life is associated with cardiovascular disease, though the mechanisms linking these two are unclear. It is also unclear whether there are critical periods in the life course when exposure to better socioeconomic conditions confers advantages or whether SEP exposures accumulate across the whole life course. Inflammation may be a mechanism linking socioeconomic position (SEP) with cardiovascular disease. In a large sample of older residents of Guangzhou, in southern China, we examined the association of life course SEP with inflammation. METHODS: In baseline data on 9,981 adults (≥ 50 years old) from the Guangzhou Biobank Cohort Study (2006-08), we used multivariable linear regression and model fit to assess the associations of life course SEP at four stages (childhood, early adult, late adult and current) with white blood, granulocyte and lymphocyte cell counts. RESULTS: A model including SEP at all four life stages best explained the association of life course SEP with white blood and granulocyte cell count for men and women, with early adult SEP (education) making the largest contribution. A critical period model best explained the association of life course SEP with lymphocyte count, with sex-specific associations. Early adult SEP was negatively associated with lymphocytes for women. CONCLUSIONS: Low SEP throughout life may negatively impact late adult immune-inflammatory status. However, some aspects of immune-inflammatory status may be sensitive to earlier exposures, with sex-specific associations. The findings were compatible with the hypothesis that in a developing population, upregulation of the gonadotropic axis with economic development may obscure the normally protective effects of social advantage for men.

Hyperglycaemia and vitamin D: a systematic overview.

Vitamin D plays a role in a range of functions that may impact on glycaemic control. In this study we systematically report on clinical studies evaluating the impact of vitamin D on aspects of hyperglycaemia in non-pregnant adults. A total of 1,294 articles, of which 417 were reviews, were identified. No well-designed randomised, controlled trials were identified that specifically investigated the effects of vitamin D supplementation on glucose and insulin concentrations. The majority of the studies that are available were poorly designed, having limited numbers, short study duration, or were conducted in volunteers with normal baseline, as measured by 25-hydroxyvitamin D (25(OH)D), concentrations or used inadequate doses of the supplements to normalise vitamin D concentrations, or used inappropriate analyses. Most studies did not observe improvements in glycaemia, with few exceptions. The results were more equivocal for aspects of insulin resistance. Most found no benefit on measures of insulin resistance, although some did. However, more studies described improved insulin release, although data from the studies to date are really inadequate to provide any reliable conclusions. Well-conducted randomised, controlled trials with adequate vitamin D doses are required to effectively assess whether this vitamin can reduce the incidence of diabetes.

Lower lung cancer mortality in obesity.

BACKGROUND: Malignancy is the leading cause of death in Hong Kong, and lung cancer tops the list of all cancer deaths. METHODS: A cohort of clients aged ≥65 years, enrolled at 18 elderly health centres in Hong Kong from 2000 to 2003, was followed up prospectively through linkage with the territory-wide death registry for causes of death until 31 December 2008, using the identity card number as unique identifier. All subjects with suspected cancer, significant weight loss of >5% within past 6 months or obstructive lung disease at the baseline were excluded. RESULTS: After a total of 423 061 person-years of follow-up, 932, 690 and 1433 deaths were caused by lung cancer, other tobacco-related malignancies and non-tobacco-related malignancies, respectively. Body mass index (BMI) was independently (and negatively) associated with death from lung cancer after adjustment for other baseline variables, whereas there was only a minor or no effect for other smoking-related malignancies and non-tobacco-related malignancies. Obesity with BMI ≥30 [adjusted hazard ratio (HR), 0.55, 95% confidence interval (CI) 0.38-0.80] was associated with reduced lung cancer mortality, which was more prominent than the opposing effect of underweight (adjusted HR, 1.38, 95% CI 1.05-1.79). Consistent effects of BMI were observed after stratification into never-smokers and ever-smokers and in sensitivity analysis after excluding deaths within the first 3 years. CONCLUSION: Obesity was associated with lower lung cancer mortality in this prospective cohort analysis. As the effect was rather specific for lung cancer, further studies are indicated to explore the underlying mechanism.

A systematic review of lifestyle modification and glucose intolerance in the prevention of type 2 diabetes.

Diabetes is reaching epidemic proportions. High risk groups, such as those older individuals or with glucose intolerance have been shown to exhibit a high risk of developing diabetes. We aimed to systematically identify and evaluate those studies that have investigated the impact of lifestyle interventions on the prevention of the development of incident Type 2 diabetes in those with glucose intolerance. Non-pharmacological lifestyle interventions, including manipulation of dietary intakes and physical activity levels are the main approaches taken to reduce the onset of diabetes in high risk groups, such as those with glucose intolerance. Intensive use of each of these lifestyle interventions have been shown to halve the risk of incident diabetes, although less intensive interventions appear to be less effective. Lifestyle modification is a useful weapon in the armoury of preventing the onset of diabetes, which is essential to reduce the associated increased risk of morbidity and mortality that might otherwise overwhelm health care systems in both developed and developing countries.

Passive smoking and tuberculosis.

BACKGROUND: Increasing evidence has incriminated active smoking as a causal factor for tuberculosis (TB). However, the effect of secondhand tobacco smoke exposure on TB has not been similarly elucidated. METHODS: A cohort of 15 486 female never-smokers aged 65 to 74 years and living with their surviving husband were enrolled at 18 Elderly Health Centers in Hong Kong from 2000 to 2003 and followed up prospectively through linkage with the territory-wide TB notification registry and death registry for TB and death until December 31, 2008, using an identity card number as a unique identifier. The relationship between passive smoking and the development of TB was assessed with adjustment for other baseline characteristics. RESULTS: Passive exposure to secondhand tobacco smoke in the household was independently associated with obstructive lung disease (odds [OR], 1.43; 95% confidence interval [CI], 1.16-1.77) and diabetes mellitus (OR, 1.13; 95% CI, 1.02-1.26) at baseline and with the development of both active TB (hazard ratio [HR], 1.49; 95% CI, 1.01-2.19) and culture-confirmed TB (HR, 1.70; 95% CI, 1.04-2.80) on prospective follow-up after potentially confounding background variables were controlled for. Passive smoking accounted for 13.7% of active TB and for 18.5% of culture-positive TB in this cohort. CONCLUSIONS: Similar to active smoking, passive exposure to secondhand tobacco smoke in the household also predisposes to the development of TB. Increased emphasis should therefore be put on tobacco control in national TB programs.

Obesity and liver cancer mortality in Asia: The Asia Pacific Cohort Studies Collaboration.

While obesity is associated with liver cancer in studies from western societies, the paucity of data from Asia limits insights into its aetiological role in this population. We examined the relationship between body mass index (BMI) and liver cancer mortality using data from the Asia Pacific Cohort Studies Collaboration. In 309,203 Asian study members, 4 years of follow-up gave rise to 11,135 deaths from all causes, 420 of which were ascribed to liver cancer. BMI, whether categorised according to current guidelines for Asian groups or World Health Organisation recommendations, was not associated with liver cancer in any of our analyses.

Diabetic control and risk of tuberculosis: a cohort study.

Diabetes mellitus is associated with tuberculosis. A cohort of 42,116 clients aged 65 years or more, enrolled at 18 Elderly Health Service centers in Hong Kong in 2000, were followed up prospectively through the territory-wide tuberculosis registry for development of tuberculosis from 3 months after enrollment to December 31, 2005, by use of their identity card numbers as unique identifier. The effects of diabetes mellitus and diabetic control on tuberculosis risk were assessed with adjustment for sociodemographic and other background variables. Diabetes mellitus was associated with a modest increase in the risk of active, culture-confirmed, and pulmonary (with or without extrapulmonary involvement) but not extrapulmonary (with or without pulmonary involvement) tuberculosis, with adjusted hazard ratios of 1.77 (95% confidence interval: 1.41, 2.24), 1.91 (95% confidence interval: 1.45, 2.52), 1.89 (95% confidence interval: 1.48, 2.42), and 1.00 (95% confidence interval: 0.54, 1.86), respectively. Diabetic subjects with hemoglobin A1c <7% at enrollment were not at increased risk. Among diabetic subjects, higher risks of active, culture-confirmed, and pulmonary but not extrapulmonary tuberculosis were observed with baseline hemoglobin A1c > or =7% (vs. <7%), with adjusted hazard ratios of 3.11 (95% confidence interval: 1.63, 5.92), 3.08 (95% confidence interval: 1.44, 6.57), 3.63 (95% confidence interval: 1.79, 7.33), and 0.77 (95% confidence interval: 0.18, 3.35), respectively.

Lower risk of tuberculosis in obesity.

BACKGROUND: Obesity is increasingly prevalent in both developed and developing areas. Although undernutrition is well associated with tuberculosis, few studies have systematically examined the association with obesity. Method A cohort of 42 116 individuals 65 years or older enrolled at 18 health centers for elderly patients in Hong Kong, China (which has a tuberculosis incidence of approximately 90 per 100,000 population), in 2000 were followed up prospectively through the territory-wide tuberculosis registry for the development of active tuberculosis from 3 months after enrollment until December 31, 2005, using the identity card number as the unique identifier. The association with body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters), as categorized by the Asian standards, was assessed with the control of other baseline characteristics. RESULTS: Obese (BMI>or=30) and overweight (BMI, 25 to <30) individuals were at significantly lower risks of developing active tuberculosis than normal-weight individuals (BMI, 18.5 to <25), with hazard ratios (95% confidence intervals) of 0.36 (0.20-0.66) and 0.55 (0.44-0.70), respectively, after adjustment for baseline demographic, social, and clinical variables. An inverse linear association was observed predominantly for pulmonary but not extrapulmonary tuberculosis. This association persisted after controlling for potential confounders or excluding individuals with known tuberculosis risk factors. CONCLUSIONS: Obesity is associated with a lower risk of active pulmonary tuberculosis in the older population of Hong Kong. The presence of such a strong but selective association across the whole spectrum of BMI could have major biological, clinical, and/or epidemiological implications. Further studies are indicated to explore the underlying mechanisms, potential clinical utilities, and possible epidemiological consequences.

Smoking and tuberculosis among the elderly in Hong Kong.

A cohort of 42,655 clients that were first registered with the Elderly Health Service in 2000 were followed prospectively through the tuberculosis (TB) notification registry until the end of 2002. A total of 286 active TB cases (186 culture confirmed) were identified. The annual TB notification rates were 735, 427, and 174 per 100,000 among current smokers, ex-smokers, and never-smokers, respectively (p < 0.001). The trend in TB risk persisted after the control of background characteristics using Cox proportional hazards analysis (adjusted hazard ratios [HRs]: 2.63, 1.41, and 1, p < 0.001). In comparison with never-smokers, current smokers had an excess risk of pulmonary TB (adjusted HR, 2.87; 95% confidence interval [CI], 2.00-4.11; p < 0.001), but not extrapulmonary TB (adjusted HR, 1.04; 95% CI, 0.33-3.30; p = 0.95). Among the current smokers, those who developed TB smoked more cigarettes per day than those who did not (13.43, SD 8.76 vs. 10.96, SD 7.87, p = 0.01). A statistically significant dose-response relationship was observed with respect to active TB and culture-confirmed TB (both p < 0.05). Smoking accounted for 32.8% (95% CI, 14.9-48.0%), 8.6% (95% CI, 3.3-15.1%), and 18.7% (95% CI, 7.7-30.4%) of the TB risk among males, females, and the entire cohort, respectively. Approximately 44.9% (95% CI, 20.7-64.6%) of the sex difference was attributable to smoking.