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Volume 13 (1); June 1991
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Original Articles
Estimation bias arising from unmached analysis of 1-to-2 matched triplets in case-control study.
Keun Young Yoo, Seok Jin Kang
Korean J Epidemiol. 1991;13(1):80-86.
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Abstract
A bias may arise, when unmatched analysis is done to get an asymptotic maximum likelihood estimate from an 1-to-2 matched data set in a case-control study. Quantification of the bias showed that it could be in either direction of underestimation or overestimation of matched odds ratio. It depends on four different components : matched odds ratio, ratio of exposure/unexposure among cases, difference of the concordants among the case-exposures, and difference of the concordants among the case-unexposures. The direction of the bias was discussed in a simple univariate setting with actual examoles. It suggests that results of this study can be applied to the analysis of matched data in order to predict potential estimation bias in the analytic stage.
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Hypertension control in an Asian urban community: a controlled comparison of screening alone versus a program of patient education and follow-up tracking.
W Daniel Jones, Kyung Im Chung, Sung Chin Kim, Charles Pharm Sands
Korean J Epidemiol. 1991;13(1):73-79.
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Abstract
This controlled prospective study was designed to test the benefit and feasibility of patient education and tracking techniques in long term hypertension control in Korea. Subjects were selected from random blood pressure screening in two neighborhoods. The study group(n=30) was given education about hypertension and was followed through a patient tracking program. The control group(n=25) was informed of their high blood pressure and only advised to seek therapy. At the end of one year, 16% (4/25) of the control group and 87% (26/30) of the study group reported compliance to regular therapy(p<0.001, chi square test). Mean diastolic blood pressure for the control group after one year was 102±16.9mmHg and for the study group 91±8.9mmHg(p<0.01,unpaired t-test). It is concluded that a program of patient education and patient tacking greatly enhances the likelihood of compliance with treatment and adequate blood pressure control in an Asian community.
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Controlled trial of transdermal nicotine patch in tobacco withdrawal.
Heechul Oh, Ilsoon Kim, Seonha Jee, Taeyong Shon, Cheongmo Nam
Korean J Epidemiol. 1991;13(1):63-72.
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Abstract
To determine the effects of transdermal nicotine patch on the withdrawal of smoking, a randomized, double-blind, placebo-controlled trial with 101 male volunteers was conducted. A total of 71 persons with nicotine patch and 30 with placebo were observed for six weeks. Anti-Smoking education with video, slides, and lectures preceded the trial. Abstinence from smoking was confirmed by urine cotinine level (<300ng/ml) at the end of sixth week of abstinence trial. Sixty-two percents of the nicotine group and 33 percents of placebo group succeeded in withdrawal of smoking respectively after six weeks. Craving indices for tobacco were moderate in both groups, but diminished over the course of treatment. Complication rates of attaching patches amount to 46.5% (33/71) in nicotine group, most frequent ones being itching sensation(23.9%), erythema(12.7%), and difficulty in concentration(9.9%) during the first week. Those of placebo group were 36.7% (11/30), difficulty in concentration(20.0%), itching sensation (16.7%), and erythema(6.7%) respectively. The result of this study showed a evidence that transdermal nicotine patch is effective in smoking withdrawal among persons with desire to abstain from smoking at least for a period of six weeks.
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A study on time-series changes of visual acuity and related factorsfor high school students in Seoul.
Jiyeon Park, Il Soon Kim, Hee Choul Oh
Korean J Epidemiol. 1991;13(1):52-62.
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Abstract
The purpose of this study was to observe the ten-year changes of visual acuity and to determine the factors of reducing visual acuity-especially learning musical instrument-. For the study, data from ten-years health record of one high school in Seoul that checked by school yearly and self-written questionnaire was analysed. The subject of study were 314 (150 : male, 164 : female). The results of study were summarized as follows. 1. The average visual scuity of female was more reduced than male by aging during past ten years. The oneset of low average visual acuity that defined less than 1.0 in this study was third grade of elemantary school in femals and second grade of middle school in male. In male, the rate of low visual acuity increased by aging but in female the rate fluctuated. 2. The propotion of low visual acuity at third grade of high school was 54.0% in male, 74.0% in female. 3. The performance of middle and high school was associated with low visual acuity but not statistically significant in female, other general factors of visual acuity were statistically insignificant. 4. In family history of visual acuity, low visual acuity were associated with putting on mother’s and brother’s glasses but not statistically significant. 5. The group of low visual acuity at third grade of high school was longer in learning musical instrument than group of normal visual acuity but not statistically significant. 6. The average visual acuity of group learning musical instrument was lower than group not learnig. The onset of low average visual acuity of group learning musical instrument was earlier than group not learning. 7. By the period of learning musical instrument, rate of low visual acuity were increased and statistically significant, but by the level of operating instrument was not statistically significant. To sum up the results, visual acuity was gradually reduced by aging and the onset of low visual acuity of female was earlier than male. At all age the average of female’s visual acuity was lower than male’s. The onset of low visual acuity of group learning musical instrument was earlier than group not learning musical instrument and the average visual acuity of group learning musical instrument was lower than group not learning musical instrument.
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Diet and stomach cancer: a case-control study in Korea.
Hyun Kyung Moon
Korean J Epidemiol. 1991;13(1):33-51.
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Abstract
The relation between diet and stomach cancer was examined in a case-control study in Korea. A total of 56 cases were identified at the National Medical Center and 140 controls were selected out at the Chung-Nam province between July 1988 and Nov. 1988. Dietary intake was measured by the quantitative food frequencey questionnaire and recall method. The frequency of intake for each food items and usual daily intake of each nutrients were determined for the subject. The mean intake of energy, protein, carbohydrate, iro, vitamin A, thiamin and niacin was lower for cases than for controls(P<0.05). The odds ratio for the lower intake of iron than the level of the recommended dietary allowances(RDA) was 11.4(95% confidence interval(CI) 5.4 - 22.6). The corresponding odds ratios were 4.8(95% CI 2.4 - 9.2) for vitamin A, 4.1(95% CI 1.6 - 9.3) for thiamin and 6.2(95% CI 1.9 - 8.2) for niacin. The mean frequency of intake for smoked meat, coffee and alcohol was lower for controls than for cases (P<0.05). The odds ratio for the highest quartile of coffee was 1.9(95% CI 1.0 - 3.7) and of alcohol was 1.9(95% CI 1.0 - 3.7). Assessment of the interrelations between diet and stomach cancer suggest that the lower intake of nutrients than RDA specially iron and the intake of alcohol and coffee may contribute to the risk of stomach cancer in Korea.
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Survey on HIV seropositives in Korea.
Young Keol Cho, Woong Soo Lee, Yun Hwan Lee, Duk Hyoung Lee, Kye In Ko, Yung Oh Shin
Korean J Epidemiol. 1991;13(1):23-32.
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Abstract
A survey to evaluate the overall aspects concerning the life-style of HIV-infected persons was conducted on 48 out of 130 HIV(Human Immunodeficiency Virus) seropositives currently under continuous monitoring. Questionnaires consisted of 33 statements to assess seven areas : personal information, confidentiality, relationship with other people, economic problems, occupation, treatment and health, and knowledge about AIDS. The major results of the study are as follows : 1. The study population consisted of 43 males(90%) and 5 females(10%), mostly in their twenties. According to the marital status, 27 were single, 17 married, and 4 divorced. 2. Of the respondents, 79.2% were satisfied with confidentiality provided by the government and valued confidentiality above everything else. It was found that 65% relied on the current system of maintaining confidentiality. 3. Of the respondents, 30(63%) had no sexual intercourse following HIV infection and 18(37%) had sexual contact. Of the 18 persons who had sexual contact, 14(78%) always used condom, 3(17%) used it occasionally, and 1(6%) never used it. Education levels, age, marital status did not play a significant role in regard to condom use. 4. Persons to whom the respondents told about their HIV status were brother or sister(28%), parents(23%), spouse(21%), and friend(13%). Twenty-one (44%) did not tell anybody. The period of time the respondents knew of their infection status did not have significant influence on talking about their HIV status to others. 5. In response to questions concerning occupation and economy, 48% responded that they changed their job by their own choice and 63% answered that they had some economic difficulties. 6. Forty-eight percent responded that they had sufficient knowledge on AIDS and the most concerned issue was the subject on new treatment agents(54%).
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A follow-up study on the chronological changes of HBV serologicmarkers in a rural community, Korea.
Bo Youl Choi, Yeong Tae Kim, Ung Ring Ko, Sae Jung Oh, Hung Bae Park
Korean J Epidemiol. 1991;13(1):6-22.
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Abstract
To estimate incidence rate of HBV infection, prevalence rate of chronic carrier and seroconversion rate of anti-HBs, the chronological changes of HBV serologic markers including HBsAg, Anti-HBs and Anti-HBc were studied using radio-immunoassay(RIA). Two consecutive prevalence surveys were carried out in 14 months ; the first one, from September to December, 1988 and the follow-up, from November, 1989 to March, 1990. Total study subjects were 314 persons(2-85 years in age) who had never been vaccinated against HBV and lived in a typical rural community (Yangpyeong Gun, Gyeong-Gi Do, Korea). The results are summarized as follows. 1. The HBV serological markers chronologically changed in a wide variety of pattern. Serologic profiles with HBsAg were more variable than the other profiles. 2. The incidence rate of HBV infection was estimated at 10.26% (95% CI ; 5.77-15.38%) and prevalence rate of HBsAg chronic carrier, at 5.40% (95% CI ; 3.18-7.96%). There were no statistically significant differences by age and sex in both the incidence rate of HBV infection and the prevalence rate of chronic carrier. 3. Seroconversion rate of Anti-HBs positives was 9.76% (95% CI ; 4.88-15.45%). 4. The level of HBsAg and Anti-HBs titer at the first prevalence survey had a predictive value in forecasting the chronic carrier state of HBsAg and seroconversion of Anti-HBs positive. Seroconversion rate of only Anti-HBs positives(25.00%) was substantially higher than that of the cases of Anti-HBs and Anti- HBc both positive(6.45%),. The result suggests that further follow-up study, for a longer period with the more frequent examinations of HBV serologic markers, will be necessary to make a better understanding of the natural course of HBV infection.
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Epidemiol Health : Epidemiology and Health