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무응답이 있는 설문조사연구의 접근법 : 한국노인약물역학코호트 자료의 평가
백지은,강위창,이영조,박병주,Baek, Ji-Eun,Kang, Wee-Chang,Lee, Young-Jo,Park, Byung-Joo 대한예방의학회 2002 예방의학회지 Vol.35 No.2
Objectives : A common problem with analyzing survey data involves incomplete data with either a nonresponse or missing data. The mail questionnaire survey conducted for collecting lifestyle variables on the members of the Korean Elderly Phamacoepidemiologic Cohort(KEPEC) in 1996 contains some nonresponse or missing data. The proper statistical method was applied to evaluate the missing pattern of a specific KEPEC data, which had no missing data in the independent variable and missing data in the response variable, BMI. Methods : The number of study subjects was 8,689 elderly people. Initially, the BMI and significant variables that influenced the BMI were categorized. After fitting the log-linear model, the probabilities of the people on each category were estimated. The EM algorithm was implemented using a log-linear model to determine the missing mechanism causing the nonresponse. Results : Age, smoking status, and a preference of spicy hot food were chosen as variables that influenced the BMI. As a result of fitting the nonignorable and ignorable nonresponse log-linear model considering these variables, the difference in the deviance in these two models was 0.0034(df=1). Conclusion : There is a lot of risk if an inference regarding the variables and large samples is made without considering the pattern of missing data. On the basis of these results, the missing data occurring in the BMI is the ignorable nonresponse. Therefore, when analyzing the BMI in KEPEC data, the inference can be made about the data without considering the missing data.
오병희(Byung Hee Oh),김창엽(Chang Yup Kim),이건세(Kun Sei Lee),강영호(Young Ho Khang),이영조(Young Jo Lee),강위창(Wee Chang Kang) 대한내과학회 1999 대한내과학회지 Vol.56 No.3
N/A Objectives : To establish prevalence of hypertension in rural area of Korea, we surveyed adult residents older than 30 years, based on the recommendation and classification of JNC-5(Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure). Methods : From December 1996 to February 1997, we studied 4,209 persons in 41 rural areas purposely sampled nationwide. Blood pressure was checked twice at the time of the first visit and again checked twice after one week later for the person fell under hypertension criteria at the first visit. Persons fell under hypertension criteria at the first visit without second visit for recheck were categorized as suspected hypertension. For the suspected hypertension, we predicted whether fell under criteria by logistic regression model. Results : 1) The distributions of blood pressures show unimodal curve, skewed to the right. The peaks of the systolic blood pressure was between 120∼129㎜Hg, tending to move to the right for the age of 50-and-over in male, 70-and-over in female. But peaks of the diastolic blood pressure were consistent between 80∼84㎜Hg in both sexes. The distributions of blood pressures for male were slightly deviated to the right compared with those of the female. 2) The crude prevalence rate of hypertension, defined as systolic blood pressure ≥140㎜Hg or diastolic blood pressure ≥90㎜Hg or taking anti-hypertensive medication, was 25.94%. And the prevalence rate of suspected hypertension was 5.54%. Through the logistic regression model, the prevalence of hypertension was estimated as 29.94%. Age-sex-adjusted prevalence rate for the rural area-Myon regions- was 25.94%, if adjusted to the age-sex composition of the 1995 national census population. 3) Prevalence rate was 27.76% in male and 30.03% in female, if adjusted to the age-sex composition of the base population of this study. Prevalence rate progressively increased with age, higher in men than women before about age 60. 4) Prevalence rates among eight Provinces(Do) was different. Unadjusted rates for Kyonggi Province was 24.74%, and rates for Chonnam Province was 34.18%. But there was no significant differences of the prevalence rate between inland and seaside. 5) By logistic regression model, 65.39% of stage 1 hypertension and 75.51% of stage 2 hypertension at the first visit were estimated as to be included in hypertension criteria. 6) By the JNC-5 classification, only 22.33% of the patients taking anti-hypertensive medication was being controlled. Conclusion : The prevalence rate of hypertension by classification of JNC-5 at rural area was 25.94%. We could not find significant differences of prevalence rate between inland and seaside. Follow-up measurement of blood pressures will be needed to establish more valid prevalence rates of hypertension.
이영조,이명철,강위창,이명묵,이동수,정준기,강원준,천기정,장명진 대한핵의학회 2000 핵의학 분자영상 Vol.34 No.1
Purpose: Dipyridamole stress myocardial perfusion SPECT could predict prognosis, however, long-term follow-up showed change of hazard ratio in patients with suspected coronary artery disease. We investigated how long normal SPECT could predict the benign prognosis on the long-term follow-up. Materials and Methods: We followed up 1169 patients and divided these patients into groups in whom coronary angiography were performed and were not. Total cardiac event rate and hard event rate were predicted using clinical, angiographic and SPECT findings. Predictive values of normal and abnormal SPECT were examined using survival analysis with Mantel-Haenszel method, multivariate Cox proportional hazard model analysis and newly developed statistical method to test time-invariance of hazard rate and changing point of this rate. Results: Reversible perfusion decrease on myocardial perfusion SPECT predicted higher total cardiac event rate independently and further to angiographic findings. However, myocardial SPECT showed independent but not incremental prognostic values for hard event rate. Hazard ratio of normal perfusion SPECT was changed significantly (p<0.001) and the changing point of hazard rate was 4.4 years of follow up. However, the ratio of abnormal SPECT was not. Conclusion: Dipyridamole stress myocardial perfusion SPECT provided independent prognostic information in patients with known and suspected coronary artery disease. Normal perfusion SPECT predicted least event rate for 4.4 years. (Korean J Nucl Med 2000;34:39-54)