Epidemiology and Health

Volume 21 (1); June 1999

Original Articles

A Review Study on Comparing Treatment Effects among Subgroups.: Seonwoo Kim, Minji Kim, Soon Young Lee; Korean J Epidemiol. 1999;21(1):104-110.

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It is interested in examining treatment effect on a particular category of subjects or in comparing treatment effects among different subgroups as well as overall treatment effect due to heterogeneity of study subjects. Subgroup analyses are exceedingly common, but they are also often misleading. Conclusions based on subgroup analyses can do harm both when a particular category of people is denied effective treatment (a "false-negative" conclusion), and when ineffective or even harmful treatment is given to a subgroup of people (a "false-positive" conclusion). Because of the frequency and the importance of clinical application of subgroup analysis, researchers need to be cautious about doing subgroup analyses. This study presents guidelines to help conducting subgroup analyses correctly.; Summary

Nested Case-control Study on the Association between Alcohol and the Risk of Proximal Hip Fracture in the Elderly People in Korea.: Byung Joo Park, Kui Oak Jung, Hye Won Koo, Jong Myon Bae; Korean J Epidemiol. 1999;21(1):93-103.

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Abstract PDF: Abstract
OBJECTIVE: To assess the association between alcohol drinking and hip fracture in the elderly people in Korea. BACKGROUND: Hip fracture is known as one of the major health problems because of its high incidence and serious consequences in the elderly people. The association between alcohol consumption and hip fractures has not been directly evaluated yet in Korea. So we conducted a nested case-control study to investigate the relationship between alcohol consumption and hip fracture in the Korean elderly people. DESIGN: Nested case-control study from the Korea Elderly Pharmacoepidemiology Cohort (KEPEC), in Pusan, Korea.
METHODS
Seventy incident cases have been selected since 1993, and 280 controls have been matched with the cases by age and gender among the KEPEC. Average alcohol intake was calculated by multiplying frequency and amount of drinking and unit capacity of each alcohol type. Odds ratios of alcohol intake on the hip fracture and their confidence intervals were computed by using multiple logistic regression with Windows version SAS 6.12.
RESULTS
The elderly people's drinking rate is lower than the young people in Korea. In univariate analysis, crude odds ratio was 0.26 in male and adjusted odds ratio after contolling for age, smoking status, medication history, physical activity and body mass index was 0.36 in male. So current drinking reduces the risk of hip fracture. Adjusted odds ratio after controlling for age, smoking status, medication history, physical activity and body mass index odds ratio was 0.24 in female with moderate drinking.
CONCLUSION
We found that alcohol consumption reduces the risk of hip fracture in the elderly Korean. However, we could not explain the plausible mechanism with our data yet. So, we suggest the further study for elucidating the possible mechanism of the finding including the possible association between nutritional status, alcohol drinking and bone marrow density in the elderly.; Summary

An Analysis on the Factors Associated with Cancer Screening in a City.: Woon Nyung Roh, Won Chul Lee, Young Bok Kim, Yong Mun Park, Hong Jae Lee, Kwang Ho Meng; Korean J Epidemiol. 1999;21(1):81-92.

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This study is aimed at preparing basic data required for establishment of a cancer screening program by examining the status of cancer screenings performed by residents in a community and the factors that have an effect on determination for a cancer screening by residents. Cervix, breast and stomach cancers were chosen as target cancers of the study due to the fact that merits of screening for these cancers have been proved by studies done in different countries. In order to find out the status of cancer screening and the factors having an effect on the determination for a cancer screening, 10 Dongs and a total of 1988 people were selected as study area and subjects by a random cluster sampling method, and the subjects were questioned on different aspects by questionnaires. Additionally, in order to find out how cancer screening is performed at medical facilities and how cancer screening is recommended by doctors, medical facilities doing cancer screening were also questioned. The results of the study are as follows: 1. In the case of the screening of the stomach cancer, 16.1% of male subjects and 25.6% of female subjects turned out to have had one or more screening for the cancer. In the cases of the breast and the cervical cancers, 21.6% and 62.6% of the subjects turned out to have had one or more screenings respectively. 2. As to the screening for the stomach cancer, there was a tendency that more of the subjects with lower level education, excepting those without education, had themselves screened for the cancer. Higher screening rates were shown by the subjects in higher ages, those who visited doctors regularly. 3. As to the screening rate by education levels, a high rate of screening was shown by the subjects with above-university education level and there was not a big difference between the screenings done for high school graduates and for those with lower education levels. Regarding the rates of screening by age groups the screening rate turned out to be higher with the higher ages. Screening rates, checked on the basis of the income levels, did not show a big differences between income levels. 4. The highest rate of screening for the breast cancer was shown by the subjects with postgraduate level of education and regarding the rate by income level, a slightly higher level was shown by the subjects with the monthly income of the 2,010,000 won, but the difference between the rates of screening by subjects at different income levels was overall not significant. 5. The rates for selecting the health screening facilities were higher in orders of the reasons that 1) they were close: 2) service was excellent and 3) equipment and facilities were good. Based on the above-mentioned results obtained by the study, it is anticipated that this study will play a vital role as basic data for the development and execution of cancer screening program for a community, and the analysis, done on the basis of the status of the cancer screening, of the factors related to the determination for the cancer screening showed that for the development of a cancer screening program, factors like income levels, education levels, whether people consult doctors regularly and the local government' care for health in a community should be considered, and in addition to which active participation of doctors in the program is also requested.; Summary

A Study on Patterns of Dose for Radiation Workers in Korea.: Soo Yong Choi, Tae Hwan Kim, Cha Kwon Chung, Chul Koo Cho; Korean J Epidemiol. 1999;21(1):72-80.

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This study presents data on the externally received doses for radiation workers who used the Korea Radioisotope Association's personal monitoring and dose record keeping service from 1984. Distributions of annual dose by age of worker and occupational category were given. The number of radiation workers registered was 23,257 in 1997. The trend of the number of radiation workers and their annual doses increased since 1984. The measured radiation dose were generally low. The collective annual dose and the mean annual dose were 33.45 Sv and 1.44 mSv, respectively. Very few workers(0.5%) exceeded 20 mSv(2 rem) and only 1 exceeded 50 mSv, the legal limit for dose.; Summary

Occupational Relationship of Cancer Patients Diagnosed in Two University Hospitals.: Geun Ryang Bae, Hyun Sul Lim, Doohie Kim; Korean J Epidemiol. 1999;21(1):64-71.

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OBJECTIVES
This study was performed to evaluate the occupational relationship on 190 cases of cancer selected out of 622 cases of cancer registered in two university hospitals from January 1, 1996 to December 31, 1997.
METHODS
The selection criteria was for the patient to be more than 40 years old with lung, liver, urinary bladder, nasal cavity and skin cancer or leukemia. We reviewed the medical records to update the missing data and occupational histories. Telephone interviews were used to obtain complete occupational histories on the subjects.
RESULTS
The sites of cancer in the order of relative frequency was lung (51.0%), followed by liver (32.9%), urinary bladder (14.1%) and skin (2.0%) in male, liver (41.5%), followed by lung (31.7%), skin (19.5%) and urinary bladder (7.3%) in female. The occupational histories of 190 cases with suspected cancer-causing occupations were recorded 5.8% on the doctor's medical records and 33.2% on the nursing records. The response rates of the telephone interviews were 87.4%. The distribution of occupation according to the telephone interviews was farmer (47.7%), office worker (16.1%), salesman (12.8%), production worker (6.7%), simple laborer (3.4%) and unknown (13.4%) in male, housewife (63.4%), farmer (17.1%), saleswoman (9.8%) and unknown (9.8%) in female. And there were two cases of suspected occupational relationships in the lung cancer cases.
CONCLUSIONS
We could not discover definite cases of occupational cancer but found out two cases of suspected occupational relationships. Occupational cancer is likely to increase in the near future, so the efforts to detect occupational relationships with cancer should be continued.; Summary

Factors for Chronic Hepatitis Defined as Elevated Level of Aminotransferases among Koreans.: Jin Ho Chun, Jong Tae Lee, Hae Sook Sohn; Korean J Epidemiol. 1999;21(1):53-63.

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Sustained abnormal liver function is closely associated with chronic hepatitis in Korea with high prevalence of hepatitis B infection. Follow up about AST and ALT on 839 adults(male 727, female 112) was executed with interval of at least 6 months for 2 years to evaluate the factors contribute to the progression of chronic hepatitis. HBsAg, HBsAb, anti-HCV, body mass index(BMI), total cholesterol, fasting blood sugar(FBS), Clonorchis sinensis in stool(Cs), fatty liver on abdominal sonogram and alcohol habit were also checked. We defined abnormal liver function as both of AST 35 U/L and ALT 50 U/L. As the result of first time liver function test(LFT), the frequency of abnormal liver function was 13.6%(114/839). The positive rate of HBsAg and HBsAb was 7.0% and 73.9%, respectively, and the positive rate of anti-HCV and Cs was 0.7% and 1.3%. As the result of the follow up, 6.2%(52/839) in total has a tendency of chronic hepatitis with sustained abnormal LFT. Among abnormal LFT, 45.6%(52/114) was sustained LFT abnormality, and 12.8%(93/725) was aggravated LFT abnormality from normal LFT at the first check. From these results, male and hepatitis B infection were evaluated as important factors for the progression of chronic hepatitis. HBsAb considered that has a protective effect to the progression of chronic hepatitis. Therefore, even though no symptoms or sign, periodic examination for hepatitis B marker and LFT is important to control the chronic hepatitis, especially for male. Furthermore, because only 25%(13/52) of sustained abnormal LFT was HBsAg positive, it suggests that further study for evaluating the factors except hepatitis B infection would be needed for the control of chronic hepatitis.; Summary

Incidence Density and Risk Factors of Low Back Pain among the Workers in a Welding Material Manufacturing Factory.: Ju Tae Park, Hyun Sul Lim; Korean J Epidemiol. 1999;21(1):36-52.

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This study was performed to understand the incidence density and detect the risk factors of occupational low back pain. A cross-sectional study was conducted with a questionnaire in a welding material manufacturing factory in October, 1993. Therefore, we selected 140 workers who had never complained of low back pain as cohorts. Also, we added 236 newly entered persons who had never complained of low back pain. The total number of cohorts were 376 workers. And then we continued with a questionnaire survey in October, 1996 and with a questionnaire survey and medical examinations by a specialist in October, 1997. Follow-ups were done for 337 workers. The number of newly developed low back pain among workers were 127. The characteristics of low back pain were as follows. The durations of pain were less than or equal to 2 days (42.6%), from 3 days to less than 1 week (8.7%), from 1 week to less than 1 month (11.0%), 1 month or more (6.2%). The frequency was everyday (7.9%), once per week (21.3%), once per month (14.2%), once per 2-3 months (9.4%), once per 5 months (11.0%). The severity of pain was slight (9.4%), mild (33.1%), moderate (13.4%), severe (10.2%) and very severe (1.6%). The onset of most low back pain was insidious (41.7%). The diagnosis of low back pain was muscle strain (37.8%), lumbar sprain (23.6%) and myofacial pain syndrome (3.9%). The number of newly developed low back pain among workers were 127, their incidence density was 15.7 per 100 person-years. In univariate analysis, age, marital status, educational level, smoking habit, category of job, tenures and frequency of stretching exercises showed a statistical significance. The multivariate logistic regression analysis confirmed that category of job and tenures (p<0.05) were independent risk factors for low back pain among workers. The number of newly developed occupational low back pain among production workers were 71, their incidence density was 11.3 per 100 person-years. In univariate analysis, age, marital status, educational level, regular exercise, tenures, posture of waist and lifting of heavy materials showed a statistical significance. The multivariate logistic regression analysis confirmed that posture of waist (p<0.05) and lifting of heavy materials (p<0.1) were independent risk factors for occupational low back pain among production workers.; Summary

Population-adjusted Mean Age at Incidence (PAMA) for Comparing Incidence Patterns with Age in Different Populations.: Yoon Ok Ahn, Moo Song Lee, Weechang Kang, Chung Min Lee, Youngjo Lee; Korean J Epidemiol. 1999;21(1):31-35.

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Standardized incidence rates have been widely used for comparing incidence patterns between populations, adjusting for differences in demographic structure. These rates can compare overall incidence levels, but to fully understand incidence patterns, an index which links incidence with age is also needed. The authors proposed a statistical method for estimating population-adjusted mean age of incidence (PAMA), based on Poisson distribution and Fieller's theorem. The index was applied with several modifications to data relating to the incidence of breast cancer among Caucasian women living in Los Angeles.; Summary

A Study on the Behavioral Factors Related to Stomach Cancer Screening among Adults in a Rural Area.: Young Bok KIM, Won Chul Lee; Korean J Epidemiol. 1999;21(1):20-30.

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The purpose of this study was to investigate the behavioral factors related to stomach cancer screening among adults in a rural area. The number of subjects were 270 who were consisted of 133(49.3%) of male and 137(50.7%) of female. To predict the behavior, we used the health belief model. Using methodology was self-questionnaire which included the perceived health status, the severity for stomach cancer, preventive knowledge for stomach cancer, the threat for stomach cancer, the experience of cue to action, the benefit of cancer screening and the barrier of participating screening. The associations between the behavioral factors and the experience and intention of examination of endoscopy were evaluated by the odds ratio(OR). The results were as follows : 1. 78.1% of subjects responded that they had the good health, and 56.3% of them perceived the severity of stomach cancer. The 49.6% of them were evaluated as the moderate on the preventive knowledge for stomach. Also 39.3% had the threat for stomach cancer, and 79.2% had the experience of cue to action. The almost of respondents thought the endoscopy as available method for stomach cancer screening. The major barrier factors on stomach cancer screening were fear to endoscopy, discomfort for endoscopy, high cost of examination and lack of time. 2. Although the experience for examination of endoscopy was showed to the difference by sex, age, educational level and BMI, it was not significant. However, the experience for examination of endoscopy was showed to the significant difference by the perceived health status(OR:3.47, 95% CI:1.27-9.51), the preventive knowledge for stomach cancer(OR:0.42, 95% CI:0.19-0.96) and the experience of cue to action(OR:2.57, 95% CI:1.05-6.34). 3. Also although the intention for examination of endoscopy was showed to the differences by sex, age and BMI, it was not significant. However, the intention for examination of endoscopy was showed to the significant difference by the benefit for endoscopy(OR:2.35, 95% CI:1.02-5.42) and the experience of stomach cancer screening(OR:3.47, 95% CI:1.78-6.78). In case of the preventive knowledge for stomach cancer and the experience of cue to action, it did not influence to the intention for examination of endoscopy.; Summary

Knowledges and Attitudes of Overseas Seamen on HIV Infection.: Jin Ho Chun, Bok Soon Oh; Korean J Epidemiol. 1999;21(1):8-19.

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BACKGROUND
Though AIDS is one of the most serious health problem in worldwide, there have been developed no effective control measure yet. Therefore, individual-based prevention is the only way to control AIDS. Because overseas seamen would be considered as a high risk group for HIV infection due to their life style, this study was conducted in order to provide some informations for preparing the control program fit for them.
METHODS
The knowledges and attitudes on HIV infection among 201 Korean male overseas seamen - who were belonged to the one shipping company - were surveyed through questionnaire The survey was conducted for 2 months from October 1, 1997 and the results were analyzed by PC SAS (ver 6.12).
RESULTS
The mean age of the subjects was 36.4 years old, and the average tenure was 10.6years. 69.2% of them were married. The information about AIDS was acquired mostly from television(40.3%) and newspapers or magazines(32.8%). 30.8% of them have not received any AIDS-related education, and 66.7% were not satisfied with the fidelity of education. About the knowledges on HIV infection, most of them knew relatively well about cause(84.1%), diagnosis(97.0%), epidemiology (94.5%) etc, however, they did not know about clinical spectrum and treatability well. With regard to the transmission of AIDS, most of them knew relatively well about needle(93.0%), longitudinal infection(92.5%), transfusion(91.0%), homosexuality(88.0%), trans plantation(81.6%), sexual contact (80.1%). However, they showed different responses about kiss, cough sneezing, mosquitos, and razor. With regard to the attitudes on HIV infection, they weighted 'isolation', for example, 'patients isolation'(65.7%), 'school-life isolation'(54.2%), 'divorce with his wife'(41.8%). There showed rather accurate knowledges and resonable attitudes in the educated group, and the response of 'will divorce with his wife' was higher in older group. With regard to the characteristics on sexual life, the possibility of future sexual contact was higher in the uneducated group, and intention to use of preventative condoms was higher in the seamanship group than the sailer group, but no difference by marrital status.
CONCLUSIONS
It should be emphasized to get the accurate knowledge about HIV infection through health education, especially focused on the practical levels, eg, preventative use of condoms during sexual contacts. This study has also another meanings to reveal the positive effect and to recall the motive for individual-based prevention.; Summary

Measurement Errors on Normotensive Subjects in Screening Test.: Jong Myon Bae, Dae Sung Kim, Jaiyong Kim, Yoon Ok Ahn; Korean J Epidemiol. 1999;21(1):1-7.

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BACKGROUND
Blood pressure measurements with a mercury sphygmomanometer serve as the screening test to establish the clinical diagnosis of primary hypertension. But one of the problems of hypertension screening is the variability of blood pressure measurements.
METHODS
In order to identify the measurement error of blood pressure through the biennial health screening program of Korea Insurance Medical Corporation, we compared the blood pressure of screening test with true value which defined as the mean of blood pressures taken from the direct contact and twice check-up among normotensive Seoul Cohort participants.
RESULTS
Three hundred forty-nine participants had both data of screening measurement and survey of direct contact. The means of difference in systolic and diastolic blood pressure between both data were 8.47 mmHg and 6.54 mmHg, respectively. These results showed statistical significance with paired t-test (p=0.001).
CONCLUSION
Our findings indicated that screening measurement of blood pressure had false negative. And if a epidemiologic study about blood pressure used the data of screening test, it should adjust value of systolic and diastolic blood pressure with adding 8 and 7 mmHg, respectively.; Summary

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