• Communications for Statistical Applications and Methods
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• v.21 no.6
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• pp.487-500
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• 2014

A new method to calculate the transmittable prevalence of an epidemic disease is proposed based on a back-calculation formula. We calculated the probabilities of reactivation and of parasitemia as well as transmittable prevalence (the number of persons with parasitemia in the incubation period) of malaria in South Korea using incidence of 12 years(2001-2012). For this computation, a new probability function of transmittable condition is obtained. The probability of reactivation is estimated by the least squares method for the back-calculated longterm incubation period. The probability of parasitemia is calculated by a convolution of the survival function of the short-term incubation function and the probability of reactivation. Transmittable prevalence is computed by a convolution of the infected numbers and the probabilities of transmission. Confidence intervals are calculated using the parametric bootstrap method. The method proposed is applicable to other epidemic diseases in other countries where incidence and a long incubation period are available. We found the estimated transmittable prevalence in South Korea was concentrated in the summer with 276 cases on a peak at the $31^{st}$ week and with about a 60% reduction in the peak from the naive prevalence. The statistics of transmittable prevalence can be used for malaria prevention programs and to select blood transfusion donors.

• Tuberculosis and Respiratory Diseases
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• v.80 no.3
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• pp.226-229
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• 2017

Chronic obstructive pulmonary disease (COPD) had been considered the only major disease that is continuing to increase in prevalence. There were a few studies about the change of the prevalence of COPD, which showed the prevalence of COPD did not increase. In this review, we report on the trends in the prevalence of COPD in Korea using the data from Korea National Health and Nutrition Examination Survey (KNHANES). The prevalence of COPD in 2015 was 13.4% (male, 21.6%; female, 5.8%). The prevalence of COPD did not change much, which ranged from 13.1% to 14.6% during the period from 2010 to 2015. Among the subjects found to have COPD by spirometry, only 2.8% had been diagnosed as COPD by physicians during the period from 2011 and 2015. In conclusion, the prevalence of COPD did not change significantly during the period from 2010 to 2015. And most COPD patients still had not been diagnosed by physicians and consequently had not been treated appropriately.

• Journal of Korean Academy of Nursing
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• v.44 no.6
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• pp.743-750
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• 2014

Purpose: The objective of this study was to provide a trend analysis of the prevalence of diabetes relative to the socioeconomic, lifestyle, and physiologic risk factors among Korean adults aged over 30 years for a 10-year period using data from the Korean National Health and Nutrition Examination Survey. Methods: Prevalence difference and the slope index of inequality were calculated for each risk factors using binomial regression by considering the repeated cross-sectional features of the data. The prevalence ratio and the relative index of inequality were calculated using log-binomial regression. Linear trend tests were performed using SAS 9.2. Results: Crude prevalence of diabetes increased over the 10-year period, and was higher for men than for women. It was very high for adults 60 years or over, consistently increasing over time. The prevalence among unemployed men, women with higher level of stress, women with hypertension, and adults with serum triglyceride levels over 135 mg/dL increased over the 10-year period in comparison with the respective control group. Conclusion: Considering the rapid economic development and associated lifestyle changes in Korea, action should be taken to control the prevalence of diabetes by both preventing and consistently monitoring these identified risk factors using a public-health approach.

• Clinical and Experimental Pediatrics
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• v.64 no.2
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• pp.86-92
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• 2021

Background: Anemia is an important health problem affecting approximately 25% of the global population. Although its prevalence is decreasing worldwide, few studies have examined the prevalence of anemia in Korean adolescents. Purpose: This study aimed to determine the prevalence of anemia in Korean adolescents over the past 21 years using data from the Korea National Health and Nutrition Examination Survey. Methods: We investigated the prevalence of anemia in adolescents aged 10-18 years for the period 1998-2018 according to sex, age, residential area, and household income. The effects of menarche age and menstruation were examined in female adolescents for the period 2001-2018. Results: Among the total 11,782 participants, the weighted prevalence of anemia was 4.0%. The prevalence of anemia in male participants significantly decreased (from 3.0% to 0.5%, P<0.001), whereas that in female participants did not change significantly over time (from 7.9% to 8.5%, P=0.054). The average age at menarche was 12.4±0.0 years; the prevalence of anemia in females increased from age 13 years onward. Multivariate analysis revealed that anemia was more common in female than male participants (odds ratio [OR], 9.88; 95% confidence interval [CI], 7.19-13.57; P<0.001). In female adolescents, the prevalence of anemia increased with age (OR, 1.26; 95% CI, 1.15-1.38, P<0.001) and was 3.6 times higher after than before menarche (OR, 3.65; 95% CI, 2.21-6.05, P<0.001). Conclusion: Over the 21-year study period, the prevalence of anemia decreased among male adolescents but did not change in female adolescents. In female adolescents, age and menarche were identified as significant risk factors that require continued attention.

• Korean Journal of Veterinary Service
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• v.41 no.2
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• pp.85-89
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• 2018

This study was conducted to demonstrate the prevalence of subclinical ketosis in dairy cattle based on days in milk and herd level. Four to five blood samples were collected in five different lactation periods and analyzed for ${\beta}$-hydroxybutyrate using a Portable Ketone Test Kit. Subclinical ketosis was observed in 12 herds at prevalence of 6.3~57.1% depending on herd level, with four herds showing more than 40% subclinical ketosis prevalence. The distribution of subclinical ketosis in the early lactation period, high yield lactation period, mid lactation period, late lactation period and dry period was 9.5%, 27.5%, 36.8%, 27.9% and 12.5%, respectively. Clinical ketosis was only observed during early lactation (9.5%) and mid lactation (2%) period.

• Journal of Preventive Medicine and Public Health
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• v.48 no.6
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• pp.301-309
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• 2015

Objectives: To investigate trends in the prevalence of allergic disease over a 9-year period. Methods: Using National Health Insurance Service (NHIS) data, the annual number of patients with allergic disease was obtained for each regional subdivisions (small cities, counties, and districts) from 2003 to 2011. Annual populations for each sub-region were obtained and used to calculate the standardized prevalence. To compare prevalence within the study period, data was standardized spatially and temporally. For standardization, demographic data was used to obtain the registered population and demographic structure for 2010, which was used to perform direct standardization of previous years. In addition, a geographic information system (GIS) was used to visualize prevalence for individual sub-regions, and allergic diseases were categorized into five groups according to prevalence. Results: The nationwide outpatient prevalence of allergic rhinitis increased approximately 2.3-fold, from 1.27% in 2003 to 2.97% in 2013, while inpatient prevalence also increased approximately 2.4-fold,. The outpatient prevalence of asthma increased 1.2-fold, and inpatient prevalence increased 1.3-fold. The outpatient prevalence of atopic dermatitis decreased approximately 12%, and inpatient prevalence decreased 5%. Conclusions: There was a large difference between prevalence estimated from actual treatment data and prevalence based on patients' self-reported data, particularly for allergic rhinitis. Prevalence must continually be calculated and trends should be analyzed for the efficient management of allergic diseases. To this end, prevalence studies using NHIS claims data may be useful.

• Parasites, Hosts and Diseases
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• v.62 no.1
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• pp.64-74
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• 2024

This pilot study aimed to investigate the effects of regional and seasonal variations on the prevalence of Theileria orientalis and the hematological profile of non-grazed dairy cows in Korea. A total of 365 clinically healthy lactating Holstein Friesian cows from 26 dairy farms in 7 provinces that were categorized into northern, central, and southern regions were sampled during the warm period from July to August and the cold period from October to December. The detection of T. orientalis major piroplasm surface protein gene and the hematology non-grazed dairy cows were analyzed using peripheral blood samples. The T. orientalis prevalence was 20.0% (73/365). The prevalence in the southern region was 35.9%, which was significantly higher than that in the central (21.6%) and northern (12.9%) regions (P<0.05). The prevalence during warm period was higher (43.0%) than that during the cold season (13.5%). The infected cows showed significantly lower erythrocyte counts in the southern region (5.8±0.6 M/㎕) and during the warm period (5.8±0.7 M/㎕) compared with those in the central and northern regions and during the cold season, which affected the extended RBC parameters, including hematocrit and hemoglobin concentrations. Our findings revealed the prevalence of T. orientalis in Korea, highlighting its high occurrence during warm periods and in certain geographical regions. Climatic factors could contribute to the health and productivity of cattle, as evidenced by the prevalence of T. orientalis and its negative impact on animals.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3581-3585
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• 2013

Background: Accurate statistics on the cancer burden are essential, both for purposes of research and for setting priorities in healthcare management. So that in vast countries with partial registration coverage, such as Iran, local data are more useful. We here estimated the incidence, prevalence and mortality time trend of four major cancer site, lung, stomach, breast and prostate, over the period 2001-2010 and provided short-range projections to 2015 in Isfahan. Materials and Methods: Estimates were derived by applying the mortality-incidence analysis method, a back-calculation approach to estimate and project incidence, prevalence and mortality of chronic degenerative disease, starting from knowledge of mortality and relative survival information. Results: Age adjusted incidence, mortality and prevalence rates in Isfahan exhibited a clear upward trend for all four sites during the period 2001-2015, with marked increasees in prostate and breast predicted for the future. Difference in incidence trends between males and females might be attributable to the difference in risk factors specific to certain cancer sites, with smoking being the main risk factor. Conclusions: In this study, males and females displayed an increasing pattern for incidence and mortality rate over the entire study period until 2015. This information can be used as basis for planning healthcare management and allocating recourses in public health.

• Journal of Preventive Medicine and Public Health
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• v.51 no.6
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• pp.310-319
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• 2018

Objectives: This study examined trends in inequality in cigarette smoking prevalence by income according to recent anti-smoking policies in Korea. Methods: The data used in this study were drawn from three nationally representative surveys, the Korea National Health and Nutrition Examination Survey, the Korea Community Health Survey, and the Social Survey of Statistics Korea. We calculated the age-standardized smoking prevalence, the slope index of inequality, and the relative index of inequality by income level as a socioeconomic position indicator. Results: Smoking prevalence among men decreased during the study period, but the downward trend became especially pronounced in 2015, when the tobacco price was substantially increased. Inequalities in cigarette smoking by income were evident in both genders over the study period in all three national surveys examined. Absolute inequality tended to decrease between 2014 and 2015 among men. Absolute and relative inequality by income decreased between 2008 and 2016 in women aged 30-59, except between 2014 and 2015. Conclusions: The recent anti-smoking policies in Korea resulted in a downward trend in smoking prevalence among men, but not in relative inequality, throughout the study period. Absolute inequality decreased over the study period among men aged 30-59. A more aggressive tax policy is warranted to further reduce socioeconomic inequalities in smoking in young adults in Korea.

• Journal of Preventive Medicine and Public Health
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• v.53 no.6
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• pp.409-418
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• 2020

Objectives: This study conducted an age-period-cohort (APC) analysis of trends in healthy lifestyle behaviors in Japan. Methods: We used National Health and Nutrition Survey data on salt intake and prevalence of smoking, drinking, and physical activity between 1995 and 2018 in Japan. Age groups were defined from 20 years to 69 years old in 10-year increments. Cohorts were defined for each age group of each year with a 1-year shift, and cohorts born in 1926-1935 (first cohort) until 1989-1998 (last cohort) were examined. We conducted a Bayesian APC analysis, calculating estimated values for each behavior by age group, period, and cohort. Results: Estimated salt intake decreased from cohorts born in the 1930s to the 1960s, but increased thereafter in both genders, and the magnitude of increase was larger for men. Estimated smoking prevalence increased in the cohorts starting from the 1930s for men and the 1940s for women, and then decreased starting in the cohorts born in the 1970s for both genders. Although estimated drinking prevalence decreased starting in the cohorts born in approximately 1960 for men, for women it increased until the cohorts born in approximately 1970. Estimated physical activity prevalence decreased starting in the cohorts born in the 1940s in both genders, but the magnitude of decrease was larger for women. Conclusions: Trends in cohort effects differed by gender, which might be related to changes in the social environment for women. Improvements in dietary and exercise habits are required in more recently born cohorts of both genders.