Mathematical Modeling of the Novel Influenza A (H1N1) Virus and Evaluation of the Epidemic Response Strategies in the Republic of Korea

Objectives: The pandemic of novel influenza A (H1N1) virus has required decision-makers to act in the face of the substantial uncertainties. In this study, we evaluated the potential impact of the pandemic response strategies in the Republic of Korea using a mathematical model. Methods: We developed a deterministic model of a pandemic (H1N1) 2009 in a structured population using the demographic data from the Korean population and the epidemiological feature of the pandemic (H1N1) 2009. To estimate the parameter values for the deterministic model, we used the available data from the previous studies on pandemic influenza. The pandemic response strategies of the Republic of Korea for novel influenza A (H1N1) virus such as school closure, mass vaccination (70% of population in 30 days), and a policy for anti-viral drug (treatment or prophylaxis) were applied to the deterministic model. Results: The effect of two-week school closure on the attack rate was low regardless of the timing of the intervention. The earlier vaccination showed the effect of greater delays in reaching the peak of outbreaks. When it was no vaccination, vaccination at initiation of outbreak, vaccination 90 days after the initiation of outbreak and vaccination at the epidemic peak point, the total number of clinical cases for 400 days were 20.8 million, 4.4 million, 4.7 million and 12.6 million, respectively. The pandemic response strategies of the Republic of Korea delayed the peak of outbreaks (about 40 days) and decreased the number of cumulative clinical cases (8 million). Conclusions: Rapid vaccination was the most important factor to control the spread of pandemic influenza, and the response strategies of the Republic of Korea were shown to delay the spread of pandemic influenza in this deterministic modelope

Prevalence of Dyslipidemia among Korean Adults: Korea National Health and Nutrition Survey 1998-2005.

BACKGROUND: Dyslipidemia is a disorder of lipid metabolism, including elevated total cholesterol, elevated triglyceride, elevated low density lipoprotein cholesterol (LDL-C), and decreased high density lipoprotein cholesterol (HDL-C). The objective of this study was to investigate recent changes in the prevalence of dyslipidemia and also the rates of awareness, treatment, and control of dyslipidemia among Korean adults. METHODS: Dyslipidemia is defined according to the National Cholesterol Education Program-Adult Treatment Panel III as total cholesterol ≥240 mg/dL, LDL-C ≥160 mg/dL, HDL-C <40 mg/dL, and triglyceride ≥200 mg/dL. The prevalence of dyslipidemia was estimated for adults aged ≥20 years using the Korea National Health and Nutrition Survey (KNHANES) in 1998 (n=6,923), 2001 (n=4,882), and 2005 (n=5,323). Rates of awareness, treatment and control of dyslipidemia were calculated for adults aged ≥30 years using the KNHANES in 2005 (n=4,654). RESULTS: The prevalence of dyslipidemia (aged ≥20 years) increased from 32.4% in 1998 to 42.6% in 2001 and 44.1% in 2005. Compared with the KNHANES in 1998, the prevalence of dyslipidemia was 47% (95% confidence interval [CI], 35% to 59%) higher in 2001 and 61% (95% CI, 49% to 75%) higher in 2005. In 2005, only 9.5% of people with dyslipidemia were aware of the disease, 5.2% used lipid-lowering medication, and 33.2% of patients with treatment reached treatment goals. CONCLUSION: The prevalence of dyslipidemia in Korea gradually increased between 1998 and 2005. These findings suggest that more intense efforts for the prevention and treatment of dyslipidemia may lead to further improvement in the management of dyslipidemia.ope

Impact of Multiple Cardiovascular Risk Factors on the Carotid Intima-media Thickness in Young Adults: The Kangwha Study

OBJECTIVES: Although risk factors for coronary artery disease are also associated with increased carotid intima-media thickness (IMT), there is little information available on the asymptomatic, young adult population. We examined the association between multiple cardiovascular risk factors and the common carotid IMT in 280 young Korean adults. METHODS: The data used for this study was obtained from 280 subjects (130 men and 150 women) aged 25 years who participated in the Kangwha Study follow-up examination in 2005. We measured cardiovascular risk factors, including anthropometrics, blood pressure, blood chemistry, carotid ultrasonography, and reviewed questionnaires on health behaviors. Risk factors were defined as values above the sex-specific 75th percentile of systolic blood pressure, body mass index, total cholesterol/high-density lipoprotein cholesterol ratio, fasting blood glucose and smoking status. RESULTS: The mean carotid IMT+/-standard deviation observed was 0.683+/-0.079 mm in men and 0.678+/-0.067 mm in women (p=0.567) and the evidence of plaque was not observed in any individuals. Mean carotid IMT increased with an increasing number of risk factors(p for trend <0.001) and carotid IMT values were 0.665 mm, 0.674 mm, 0.686 mm, 0.702 mm, and 0.748 mm for 0, 1, 2, 3, and 4 to 5 risk factors, respectively. The odds ratio for having the top quartile carotid IMT in men with 3 or more risk factors versus 0-2 risk factors was 5.09 (95% CI, 2.05-12.64). CONCLUSIONS: Current findings indicate the need for prevention and control of cardiovascular risk factors in young adults and more focus on those with multiple cardiovascular risk factors.ope

Elevated serum aminotransferase level as a predictor of intracerebral hemorrhage: Korea Medical Insurance Corporation study

BACKGROUND AND PURPOSE: Serum aminotransferase levels are known to be associated with cardiovascular risk factors, but the relation with stroke incidence is not well known. We investigated the relation between serum aminotransferase levels and the incidence of stroke. METHODS: We measured serum aspartate and alanine aminotransferase levels and traditional cardiovascular risk factors in 108 464 Korean men, aged 35 to 59 years, in 1990 and 1992. Serum aminotransferase levels were classified into 3 categories ( or =70 IU/L). The outcomes were hospital admissions and deaths from stroke subtypes (ischemic stroke, intracerebral hemorrhage [ICH], and subarachnoid hemorrhage [SAH]) from 1993 to 2002. RESULTS: During the 10 years, 1728 ischemic, 1051 hemorrhagic (718 ICH and 222 SAH), and 243 unspecified stroke events occurred. After adjustment for age and other traditional risk factors and according to Cox proportional-hazards models, serum aminotransferase level had an independent positive associations with ICH. However, ischemic stroke and SAH were not associated with aminotransferase levels. Compared with the level or =70 IU/L were 1.49 (1.21 to 1.83) and 4.21 (3.06 to 5.77), respectively. The corresponding risks for alanine aminotransferase were 1.34 (1.09 to 1.65) and 2.89 (2.09 to 4.01), respectively. These associations were consistent regardless of the level of obesity, blood pressure, fasting glucose, alcohol intake, and follow-up length. CONCLUSIONS: These findings suggest that an elevated aminotransferase level is a predictor of ICH. The biologic significance of aminotransferase level for the development of ICH merits further study.ope

Optical coherence tomography evaluation of zotarolimus-eluting stents at 9-month follow-up: comparison with sirolimus-eluting stents.

OBJECTIVE: To evaluate the vascular response at 9 months after zotarolimus-eluting stent (ZES; Endeavor) implantation using optical coherence tomography (OCT). These findings were compared with those after implantation of a sirolimus-eluting stent (SES; Cypher Select). DESIGN: Cross-sectional observational study with prospective OCT registry. SETTING: Nine months after ZES or SES implantation. PATIENTS AND METHODS: A total of 68 patients (32 ZES and 36 SES) underwent OCT at 9 months after stent implantation. The neointima hyperplasia (NIH) thickness inside each strut and percentage of NIH area at every 1 mm cross section were measured. Main outcome measurement: The degree of neointimal coverage and the prevalence of malapposition at 9 months after ZES and SES implantation using OCT. RESULTS: The mean (SD) NIH thickness (251.2 (110.0) mum vs 85.5 (53.3) mum, p<0.001) and percentage of NIH area (27.9 (9.1)% vs 11.2 (7.1)%, p<0.001) were significantly greater in ZES than in SES. The prevalence of uncovered strut as well as malapposed strut was significantly lower in ZES than in SES (0.3% vs 12.3%, p<0.001 and 0.08% vs 2.6%, p<0.001). Thrombus was not observed in ZES (0.0% in ZES vs 27.8% in SES, p = 0.001). CONCLUSIONS: Neointimal coverage in ZES was almost complete and malapposition was very rare at 9-months' follow-up.ope

Lifestyle modification and hypertension control in hypertensives.

보건학과/석사[한글] 현대인의 사망원인 중 가장 많은 비율을 차지하는 생활습관병(life-related disease)은 생활습관변화, 즉 건강행태(health behavior)를 변화함으로 인해 충분히 예방하고 관리할 수 있는 것이다. 고혈압은 생활습관 개선과 같은 비약리적인 방법을 통한 예방 및 관리가 가능하다는 많은 연구 결과에 따라 생활습관 개선은 고혈압 치료에 있어 가장 먼저 시작되는 치료법이지만 생활습관 개선을 통한 혈압 강하 효과에 대한 연구 결과는 여전히 논쟁적이며 특히 약물 치료를 시작하면 이와 같은 비약리적인 방법에 대해 다소 소홀하기 쉽다. 본 연구에서는 과천시 지역 주민을 대상으로 고혈압 진단자 중 약물 치료 중인 사람들에 대해 혈압 측정 결과 고혈압 조절군(233명)과 고혈압 비조절군(209명)으로 나누어 이들의 건강관심도와 고혈압 치료에 대한 태도 및 건강생활습관 실천 여부에 차이가 있는지를 파악하여 약물치료 중에도 건강생활습관이 혈압 강하와 관련이 있는지 알아보고자 하였다. 건강관심도와 고혈압 치료에 대한 태도 결과를 살펴 볼 때 고혈압 비조절군의 경우 건강검진과 같은 실제적인 행위는 보다 적으면서 자신의 건강에 대해서는 보다 건강한 것으로 인지하고 있었고 고혈압 치료에 대한 태도에 있어서는 고혈압 치료법에 대해서는 보다 많이 알고 있다고 응답하였으나 고혈압 치료에 대해서는 신념이 적은 것으로 나타나 이와 같은 건강인지나 치료에 대한 태도등이 환자들의 건강 행위 실천에 영향을 미치는 것으로 볼 수 있을 것이다. 운동, 체중조절, 저식염섭취, 금연, 절주 등의 건강생활습관 실천이 각 군에 있어 차이가 있는지를 알아본 결과 운동과 체중조절, 저식염섭취 등을 고혈압 조절군에서 평균 10%가량 더 많이 실천하고 있었다. 이에 대한 로지스틱 회귀분석을 실시한 결과 연령에 대해서 만 보정하였을 때는 고혈압 조절군에 속할 가능성이 운동의 경우 1.4배, 체중조절 1.6배, 저식염섭취 1.7배였으며 연령, 성, 직업, 주요 이용 의료기관에 대해서 보정하였을 때는 고혈압 조절군에 속할 가능성이 운동의 경우 1.4배, 체중조절 1.5배, 저식염섭취 1.6배 였으며 통계적으로 유의하였다. 이와 같이 고혈압 조절군의 운동, 체중조절, 저식염섭취 등과 같은 건강생활 실천율이 고혈압 비조절군에 비해 통계적으로 유의하게 높아 약물치료 중에도 생활습관행태 변화가 혈압 강하와 연관이 있는 것으로 볼 수 있다. 본 연구는 일개 지역사회 주민전체를 대상으로 하여 적절한 표본추출을 통해 실시한 조사였기 때문에 대표성을 지녔다고 보며 이에 본 연구의 의의가 있다고 할 수 있다. [영문] Life-related diseases account for the biggest portion of death causes in today's society. Thus they can be prevented and managed enough by giving some changes to everyday healthy lifestyles. There have been many researches saying that hypertension can be prevented and managed through non-pharmacologic therapies such as improving healthy lifestyles. Improving healthy lifestyles are, indeed, the very first step of hypertension treatment. But the effects of improvement in healthy lifestyles on dropping high blood pressure are still controversial, and this kind of non-pharmacologic therapy can often be neglected by the patient once a pharmacologic therapy begins. The subject of the study were drawn from the residents of Gwachoen City. Those residents who had been diagnosed as hypertension and were under medication were divided into two groups of the controlled hypertension group(233 persons) and uncontrolled hypertension group(209 persons). They were investigated to see if there were differences among them in terms of health concern, attitude toward hypertension treatment, and practice of healthy lifestyles. The research efforts were aimed to examine if healthy lifestyles could influence blood pressure dropping even during medication. The research results were as follows in terms of health concern and attitude toward hypertension treatment; in the aspect of interest in health, the uncontrolled hypertension group turned out to conduct less health-related behaviors such as getting a check-up but be in a greater tendency to think they were healthy. As for the attitude toward hypertension treatment, the same group answered they knew more of hypertension treatment but had less faith in it. It was concluded that awareness in one's health and attitude toward treatment can affect a patient's practicing health behaviors. Practices of healthy life habits including exercising, weight control, dietary salt intake, no smoking, and temperance were applied to both the groups to find out if there were any differences between them. The controlled hypertension group showed about average 10 percent higher rate in practicing the healthy lifestyles of exercising, weight control, dietary salt intake than the uncontrolld hypertension group. The logistic regression analysis was applied to the result. Adjusted for age, the possibility that the group still made the controlled hypertension group was 1.4 times higher than the other group in terms of exercising, 1.6 times in weight control, and 1.7 times in dietary salt intake. And adjusted for age, sex, occupation, and prefered medical facility, the group showed 1.4 times higher possibility to still belong to the controlled hypertension group than the other group in terms of exercising, 1.5 times in weight control, and 1.6 times in dietary salt intake. Results were statistically significant. In short, the controlled hypertension group had a higher rate, which was statistically significant, in practicing healthy lifestyles such as exercising, weight control, dietary salt intake, meaning that changes in lifestyles have something to do with blood pressure dropping even during medication. The study extracted proper samples from the whole group of residents in a city and thus can be assessed to be representative. The significance of the study can be found in this representation.ope

반복 측정한 흡연상태와 당뇨 발생과의 관련성

Dept. of Public Health/박사[한글] 세계적으로 당뇨병 유병인구는 지속적으로 증가하고 있으며 생활양식의 변화로 인하여 우리 나라에서도 당뇨병 발생 증가가 꾸준하다. 당뇨병은 그 자체라기 보다는 여러 가지 합병증으로 인하여 개인적으로나 사회적으로 질병부담이 큰 질병인 반면 생활습관의 개선을 통해 충분히 예방하고 조절할 수 있다는 것이 그 특징이다. 최근 흡연이 당뇨병의 독립적인 위험요인이라는 연구보고들이 많이 있다. 기존 연구들에서는 흡연과 당뇨병 발생에 대해서는 일관적인 결과를 제시하였으나 흡연 기간과 흡연량, 특히 금연한 사람들에 대해서는 아직 결론적이지 않다. 따라서 장기간 추적 연구를 통해 반복적으로 측정한 흡연상태를 이용하여 흡연과 내당능장애, 당뇨병 발생과의 관련성을 알아보고 또한 금연이 해당 질병 발생 위험의 예방효과가 있는지를 알아보고자 한다. 본 연구는 Korea Medical Insurance Corporation (KMIC) 코호트 자료를 이용하였다. 연구 대상은 1990년과 1992년 두 차례의 건강검진에 모두 참여한 사람 중 35-44세 남성으로 1998년과 2000년의 검진자료가 모두 있는 사람이다. 1992년 당시에 이미 질병을 가지고 있다고 응답한 사람과 혈당농도가 126 mg/dl 이상인 사람, 흡연상태가 정의한 기준에 부합하지 않은 사람은 대상에서 제외되었다. 내당능장애는 1998년과 2000년의 혈당농도평균이 100 mg/dl 이상인 경우로, 당뇨병 발생은 126 mg/dl 이상인 경우로 정의하였다. 독립변수인 흡연 (흡연상태, 흡연기간, 흡연량, 금연기간에 따른 흡연상태)과 종속변수인 내당능장애와 당뇨 발생 각각의 관계는 다중 로지스틱 회귀분석을 통하여 분석하였으며 연령, 연구 시작시점에서의 혈당농도, 체질량지수 (body mass index)와 추적기간 동안의 체중변화, 당뇨병 가족력, 음주 상태, 운동 여부 등의 변수는 통계적 방법으로 보정하였다. 연구 대상자 27, 635명 가운데 추적기간 동안 3620명이 내당능장애, 1170명이 당뇨병 발생을 보였다. 비흡연자와 비교하여 내당능장애 발생 위험은 금연자와 흡연자에서 각각 1.09 (95% 신뢰구간 0.98 - 1.21)와 1.22 (1.11 -1 .34)였고 당뇨병 발생 위험은 각각 1.22와 1.60이었으며 이는 통계적으로 유의하였다. 흡연기간과 흡연량과 관련 질병 발생에 있어서도 용량-반응 관계를 보였다. 금연기간과 내당능장애, 당뇨병 발생 위험과의 관련성은 1994년과 1995년 사이에 금연한 사람들의 경우 각각 1.35배, 2.13배 위험이 증가하였고 1994년 이전에 금연하여 금연을 지속한 경우(5년 이상)는 비흡연자에 비해 발생 위험이 약간 높았으나 통계적으로 유의하지 않았다. 요약하면, 이 연구결과는 흡연이 당뇨병 발생에 위험요인일 수 있다는 기존 연구결과들을 지지하며 흡연 예방과 금연을 통해 당뇨병 발생 위험을 줄일 수 있음을 보여주었다. [영문]Objective: To investigate the relationship between smoking status and the risk for developing impaired fasting glucose and diabetes mellitus; and to assess the effect of smoking cessation on the risk of developing impaired fasting glucose and diabetes mellitus. Design: An eight-year prospective study with baseline examinations in 1990 and 1992, and follow-up examinations in 1998 and 2000. Setting: Government and private school employees in Korea/Participants: 27,635 men aged 35 to 44 years with normal fasting serum glucose and no diseases at baseline were selected. Baseline levels of fasting serum glucose index were the mean of the 1990 and 1992 measurements, and the final levels were the mean of the 1998 and 2000 measurements. The participants were classified as 5,701 never smokers, 7,477 ex-smokers and 14,457 sustained smokers, using repeatedly measured smoking status. Main results: After an eight-year period, 21.6% and 4.2% men developed impaired fasting glucose and diabetes of never smokers, 20.4% and 3.6% of ex-smokers, and 22.8% and 4.9% of sustained smokers, respectively. Compared with never smokers, the fully adjusted relative risk of ex-smokers and sustained smokers for impaired fasting glucose was 1.09 (95% CI, 0.98 to 1.21) and 1.22 (1.11 to 1.34). The corresponding risk ratio for diabetes was 1.22 (0.96 to 1.55) and 1.60 (1.29 to 1.97), respectively. Dose-response relationships were observed between smoking duration and the risk of developing impaired fasting glucose and diabetes. For ex-smokers who quit smoking prior to 1992, a slight risk comparison to never smokers was discovered; both subjects sustained impaired fasting glucose (RR 1.02) and diabetes mellitus (RR 0.95). Subjects who quit smoking between 1992 and 1993 showed little higher risk compared with never smokers (1.09 and 1.44, respectively). However, subjects who quit smoking between 1994 and 1995 showed a significantly higher risk for impaired fasting glucose (1.35) and diabetes mellitus (2.13) Conclusion: This study indicates that smoking is associated with increased risk for development impaired fasting glucose and diabetes mellitus. Thus, the recommendation that the prevention of cigarette smoking may aid in the prevention of diabetes mellitus is supported.ope