Hyeon Chang Kim

Smoking cessation and risk of type 2 diabetes mellitus: Korea Medical Insurance Corporation Study

Background To investigate the independent effects of smoking cessation on the risk for developing type 2 diabetes mellitus (DM) in the general population. Design An 8-year prospective study. Methods This prospective study started with baseline examinations in 1990 and 1992, and continued with follow-up examinations every 2 years up to 1998 and 2000. A total of 27635 nondiabetic men, aged 35–44 years were classified as 5701 nonsmokers, 7477 ex-smokers and 14457 sustained smokers, based on repeated self-reported questionnaires in 1992, 1994 and 1996. Baseline fasting serum glucose level and other risk factors were measured in 1990 and 1992. The outcome was newly developed DM, defined as a fasting glucose level ≥7.0mmol/l in 1998 and 2000 (averaged). Results Over the 8 years, 1170 men (4.2%) developed DM. When compared with nonsmokers, the fully adjusted risk ratio of ex-smokers and sustained smokers for diabetes was 1.22 [95% confidence interval (CI), 0.96–1.55] and 1.60 (95% CI, 1.29–1.97), respectively. Among the ex-smokers, the risk for diabetes differed according to the quit-smoking period. Compared with nonsmokers, the fully adjusted risk ratio for DM in men who quit smoking before 1992, during 1992–1993 and during 1994–1995 was 0.95 (0.72–1.25), 1.44 (0.96–2.15) and 2.13 (1.51–3.00), respectively, after adjustment for age, baseline fasting serum glucose, weight change, baseline body mass index, family history of DM, alcohol consumption and exercise status. Conclusions Our results support cigarette smoking as an independent and modifiable risk factor for DM. Early smoking cessation could decrease the risk for developing DM to that of nonsmokers in the long term.

Dietary assessment methods in epidemiologic studies

Diet is a major lifestyle-related risk factor of various chronic diseases. Dietary intake can be assessed by subjective report and objective observation. Subjective assessment is possible using open-ended surveys such as dietary recalls or records, or using closed-ended surveys including food frequency questionnaires. Each method has inherent strengths and limitations. Continued efforts to improve the accuracy of dietary intake assessment and enhance its feasibility in epidemiological studies have been made. This article reviews common dietary assessment methods and their feasibility in epidemiological studies.

Prevalence and Management of Diabetes in Korean Adults: Korea National Health and Nutrition Examination Surveys 1998–2005

OBJECTIVE This research investigated recent changes in the prevalence and management status of diabetes among Korean adults. RESEARCH DESIGN AND METHODS The Korea National Health and Nutrition Examination Survey (KNHANES), a nationwide survey examining the general health and nutrition status of the Korean people, was conducted in 1998, 2001, and 2005. Using the first (1998; n = 5,645), second (2001; n = 4,154), and third (2005; n = 4,628) KNHANES datasets, in the present study, we estimated the prevalence of diabetes among Korean adults (aged ≥30 years), the proportions of known cases of diabetes, and the proportions of well-controlled cases of diabetes, as defined by either the American Diabetes Association (A1C <7%) or the International Diabetes Federation guidelines (A1C <6.5%). RESULTS In 2005, the prevalence of diabetes was estimated to be 9.1% (∼2.58 million people: 10.2% of men and 7.9% of women), including 6.2% with known diabetes and 2.9% with newly diagnosed diabetes. The prevalence of impaired fasting glucose was 17.4% (∼4.94 million people). The proportion of known cases of diabetes drastically increased from 23.2% in 1998 to 41.2% in 2001 and 68.0% in 2005 (P < 0.0001). Among known diabetic patients in 2005, 43.5 and 22.9% had A1C levels <7.0 and <6.5%, respectively. CONCLUSIONS The overall prevalence of diabetes in Korea has not changed significantly between 1998 and 2005. Physician diagnosis and treatment rates of diabetes have significantly improved during this period, but glycemic control was still poorer than that in other developed countries.

Association between nonalcoholic fatty liver disease and carotid intima-media thickness according to the presence of metabolic syndrome

OBJECTIVE Controversy exists as to whether the association between nonalcoholic fatty liver disease (NAFLD) and atherosclerosis is independent of other metabolic disorders. We examined the association between NAFLD and carotid intima-media thickness (IMT) according to the presence of metabolic syndrome (MetS). METHODS A cross-sectional analysis was performed among 556 men and 465 women, ages 30-79 years. The presence of NAFLD was evaluated ultrasonographically. Carotid IMT was determined ultrasonographically by the average of the maximal IMT at each common carotid artery. Independent associations between NAFLD and IMT were assessed using multiple linear and logistic regression models, after adjusting for age, sex, waist circumference, systolic blood pressure, fasting glucose, total/HDL-cholesterol ratio, smoking, and alcohol consumption. RESULTS After adjusting for major risk factors, subjects with NAFLD had greater carotid IMT than subjects without NAFLD (difference 0.034 mm, p=0.016). However, the difference in IMT was significant only in subjects with MetS (0.060 mm, p=0.015) and not in subjects without MetS (0.015 mm, p=0.384). Similarly, the NAFLD-associated adjusted odds ratio for increased IMT, defined as the sex-specific top quintile, was 1.63 (95% CI, 1.10-2.42) in all subjects and 2.08 (95% CI, 1.19-3.66) in subjects with MetS, but 1.18 (95% CI, 0.64-2.19) in subjects without MetS. When the analysis was performed according to the number of metabolic abnormalities, the NAFLD-IMT association was observed only in subjects with four or more abnormalities. CONCLUSION These results suggest that NAFLD is independently associated with carotid atherosclerosis only in people who have multiple metabolic abnormalities.

Low serum cholesterol and haemorrhagic stroke in men: Korea Medical Insurance Corporation Study

BACKGROUND In some prospective studies, haemorrhagic stroke occurs more frequently in individuals with low serum cholesterol than in those with higher concentrations. We aimed to determine whether low total serum cholesterol is an independent risk factor for haemorrhagic stroke (intracerebral haemorrhage and subarachnoid haemorrhage) in South Korea, a country that has a population with relatively low concentrations of total serum cholesterol. METHODS We measured total serum cholesterol and other cardiovascular risk factors in 114,793 Korean men, aged between 35-59 years in 1990 and 1992, in a prospective observational study. We used data obtained in 1992 for smoking and alcohol consumption. We divided total serum cholesterol into quintiles (<4.31 mmol/L, 4.31-<4.74, 4.74-<5.16, 5.16-<5.69 and > or = 5.69). Our primary outcomes were hospital admissions and deaths from intracerebral and subarachnoid haemorrhage in a 6 year follow-up between 1993 and 1998. FINDINGS 528 men had a haemorrhagic stroke--372 intracerebral and 98 subarachnoid haemorrhage--and 58 were unspecified strokes. The relative risks of intracerebral haemorrhage in each quintile of total serum cholesterol (lowest to highest were: 1.22 (95% CI 0.88-1.69); 0.86 (0.60-1.21); 1.08 (0.78-1.48); and 1.03 (0.75-1.41). The corresponding relative risks for subarachnoid haemorrhage were: 1.44 (0.76-2.73); 1.13 (0.59-2.20); 1.21 (0.64-2.29); and 1.12 (0.59-2.14). INTERPRETATION Low total serum cholesterol is not an independent risk factor for either intracerebral or subarachnoid haemorrhagic stroke in Korean men.

Multimarker Prediction of Coronary Heart Disease Risk: The Women's Health Initiative

OBJECTIVES The aim of this study was to investigate whether multiple biomarkers contribute to improved coronary heart disease (CHD) risk prediction in post-menopausal women compared with assessment using traditional risk factors (TRFs) only. BACKGROUND The utility of newer biomarkers remains uncertain when added to predictive models using only TRFs for CHD risk assessment. METHODS The Womens Health Initiative Hormone Trials enrolled 27,347 post-menopausal women ages 50 to 79 years. Associations of TRFs and 18 biomarkers were assessed in a nested case-control study including 321 patients with CHD and 743 controls. Four prediction equations for 5-year CHD risk were compared: 2 Framingham risk score covariate models; a TRF model including statin treatment, hormone treatment, and cardiovascular disease history as well as the Framingham risk score covariates; and an additional biomarker model that additionally included the 5 significantly associated markers of the 18 tested (interleukin-6, d-dimer, coagulation factor VIII, von Willebrand factor, and homocysteine). RESULTS The TRF model showed an improved C-statistic (0.729 vs. 0.699, p = 0.001) and net reclassification improvement (6.42%) compared with the Framingham risk score model. The additional biomarker model showed additional improvement in the C-statistic (0.751 vs. 0.729, p = 0.001) and net reclassification improvement (6.45%) compared with the TRF model. Predicted CHD risks on a continuous scale showed high agreement between the TRF and additional biomarker models (Spearmans coefficient = 0.918). Among the 18 biomarkers measured, C-reactive protein level did not significantly improve CHD prediction either alone or in combination with other biomarkers. CONCLUSIONS Moderate improvement in CHD risk prediction was found when an 18-biomarker panel was added to predictive models using TRFs in post-menopausal women.

Effects of prehypertension and hypertension subtype on cardiovascular disease in the Asia-Pacific Region

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure defined blood pressure (BP) levels of 120 to 139/80 to 89 mm Hg as prehypertension and those of ≥140/90 mm Hg as hypertension. Hypertension can be divided into 3 categories, isolated diastolic (IDH; systolic BP <140 mm Hg and diastolic BP ≥90 mmHg), isolated systolic (systolic BP ≥140 mm Hg and diastolic BP <90 mmHg), and systolic-diastolic hypertension (systolic BP ≥140 mm Hg and diastolic BP ≥90 mmHg). Although there is clear evidence that isolated systolic hypertension and systolic-diastolic hypertension increase the risks of future vascular events, there remains uncertainty about the effects of IDH. The objective was to determine the effects of prehypertension and hypertension subtypes (IDH, isolated systolic hypertension, and systolic-diastolic hypertension) on the risks of cardiovascular disease (CVD) in the Asia-Pacific Region. The Asia Pacific Cohort Studies Collaboration is an individual participant data overview of cohort studies in the region. This analysis included a total of 346570 participants from 36 cohort studies. Outcomes were fatal and nonfatal CVD. The relationship between BP categories and CVD was explored using a Cox proportional hazards model adjusted for age, cholesterol, and smoking and stratified by sex and study. Compared with normal BP (<120/80 mmHg), hazard ratios (95% CIs) for CVD were 1.41 (1.31–1.53) for prehypertension, 1.81 (1.61–2.04) for IDH, 2.18 (2.00–2.37) for isolated systolic hypertension, and 3.42 (3.17–3.70) for systolic-diastolic hypertension. Separately significant effects of prehypertension and hypertension subtypes were also observed for coronary heart disease, ischemic stroke, and hemorrhagic stroke. In the Asia-Pacific region, prehypertension and all hypertension subtypes, including IDH, thus clearly predicted increased risks of CVD.

Associations of diabetes mellitus with site-specific cancer mortality in the Asia-Pacific region

BACKGROUND Owing to the increasing prevalence of obesity and diabetes in Asia, and the paucity of studies, we examined the influence of raised blood glucose and diabetes on cancer mortality risk. MATERIALS AND METHODS Thirty-six cohort Asian and Australasian studies provided 367, 361 participants (74% from Asia); 6% had diabetes at baseline. Associations between diabetes and site-specific cancer mortality were estimated using time-dependent Cox models, stratified by study and sex, and adjusted for age. RESULTS During a median follow-up of 4.0 years, there were 5992 deaths due to cancer (74% Asian; 41% female). Participants with diabetes had 23% greater risk of mortality from all-cause cancer compared with those without: hazard ratio (HR) 1.23 [95% confidence interval (CI) 1.12, 1.35]. Diabetes was associated with mortality due to cancer of the liver (HR 1.51; 95% CI 1.19, 1.91), pancreas (HR 1.78; 95% CI 1.20, 2.65), and, less strongly, colorectum (HR 1.32; 95% CI 0.98, 1.78). There was no evidence of sex- or region-specific differences in these associations. The population attributable fractions for cancer mortality due to diabetes were generally higher for Asia compared with non-Asian populations. CONCLUSION Diabetes is associated with increased mortality from selected cancers in Asian and non-Asian populations.

Ambient particulate matter as a risk factor for suicide.

OBJECTIVE The authors assessed the relationship between exposure to ambient particulate matter and suicide in urban settings during a 1-year period. METHOD The association between particulate matter and suicide was determined using a time-stratified case-crossover approach in which subjects served as their own controls. All suicide cases (4,341) in 2004 that occurred in seven cities in the Republic of Korea were included. Hourly mean concentrations of particulate matter < or =10 microm in aerodynamic diameter (at 106 sites in the seven cities) and particulate matter < or =2.5 microm in aerodynamic diameter (at 13 sites in one city) were measured. The percent increase in suicide risk associated with an interquartile range increase in particulate matter was determined by conditional logistic regression analysis after adjusting for national holidays and meteorological factors. Subgroup analysis was performed after stratification by underlying disease (cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary disease, cancer, and psychiatric illness). RESULTS The largest associations were a 9.0% increase (95% CI=2.4-16.1) and a 10.1% (95% CI=2.0-19.0) increase in suicide risk related to an interquartile range increase in particulate matter < or =10 microm (average of 0 to 2 days prior to the day of suicide) and particulate matter < or =2.5 microm (1 day prior to the day of suicide), respectively. Among individuals with cardiovascular disease, a significant association between particulate matter < or =10 microm (average of 0 to 2 days prior to the day of suicide) and suicide was observed (18.9%; 95% CI=3.2-37.0). CONCLUSIONS Conclusions: A transient increase in particulate matter was associated with increased suicide risk, especially for individuals with preexisting cardiovascular disease.

Adult height and the risks of cardiovascular disease and major causes of death in the Asia-Pacific region: 21 000 deaths in 510 000 men and women

BACKGROUND In Caucasian populations, adult height is inversely associated with cardiovascular disease (CVD) risk and positively related to some cancers. However, there are few data from Asian populations and from women. We sought to determine the sex- and region-specific associations between height and cardiovascular outcomes, and deaths due to cancer, respiratory and injury in populations from the Asia-Pacific region. METHODS Thirty-nine studies from the Asia Pacific Cohort Studies Collaboration database were included. We used Cox proportional hazard regression models to estimate the associations between height and pre-specified outcomes. RESULTS A total of 510,800 participants with 21,623 deaths were included. Amongst men, inverse linear associations were observed between height and coronary heart disease (CHD), stroke, CVD, injury and total mortality. The hazard ratios [95% confidence intervals, (CI)] for a 1-SD (= 6 cm) increment in height ranged from 0.85 (0.80-0.91) for injury to 0.97 (0.95-0.98) for total mortality. Similar trends were found between height and CHD, haemorrhagic stroke and CVD in women. A positive linear association was observed between height and cancer mortality. For each standard deviation greater height, the risk of cancer was increased by 5% (2-8%) and 9% (5-14%) in men and women, respectively. No regional difference was observed between Asian and Australasian cohorts. Adjusting for markers of education did not alter the results. CONCLUSIONS The opposing relationships of height with CVD and cancer suggest that care is required in setting national policies on childhood nutrition lest they have unintended consequences on the incidence of major non-communicable diseases.