OBJECTIVES: Outbreaks of scarlet fever in Mexico in 1999, Hong Kong and mainland China in 2011, and England in 2014-2016 have received global attention, and the number of notified cases in Korean children, including in Jeju Province, has also increased since 2010. To identify relevant hypotheses regarding this emerging outbreak, an age-period-cohort (APC) analysis of scarlet fever incidence was conducted among children in Jeju Province, Korea. METHODS: This study analyzed data from the nationwide insurance claims database administered by the Korean National Health Insurance Service. The inclusion criteria were children aged ≤14 years residing in Jeju Province, Korea who received any form of healthcare for scarlet fever from 2002 to 2016. The age and year variables were categorized into 5 groups, respectively. After calculating the crude incidence rate (CIR) for age and calendar year groups, the intrinsic estimator (IE) method was applied to conduct the APC analysis. RESULTS: In total, 2345 cases were identified from 2002 to 2016. Scarlet fever was most common in the 0-2 age group, and boys presented more cases than girls. Since the CIR decreased with age between 2002 and 2016, the age and period effect decreased in all observed years. The IE coefficients suggesting a cohort effect shifted from negative to positive in 2009. CONCLUSIONS: The results suggest that the recent outbreak of scarlet fever among children in Jeju Province might be explained through the cohort effect. As children born after 2009 showed a higher risk of scarlet fever, further descriptive epidemiological studies are needed.
Child ; China ; Cohort Effect ; Delivery of Health Care ; Disease Outbreaks ; England ; Epidemiologic Studies ; Exotoxins ; Female ; Hong Kong ; Humans ; Incidence ; Insurance ; Korea ; Methods ; Mexico ; National Health Programs ; Scarlet Fever ; Streptococcus pyogenes

Rapid aging, economic development, lifestyle westernization, hygiene improvement, and scientific development have contributed for the epidemiologic changes of gastric cancer. This study aimed to review the descriptive epidemiology, risk factors, and prevention of gastric cancer in Korea. Age-standardized incidence and mortality of gastric cancer have decreased and showed age effect and cohort effect. Annual percent change in the incidence of gastric cancer has been prominent in recent years. Major risk factor of gastric cancer is Helicobacter pylori infection. Although H. pylori infection was associated with only non-cardia gastric cancer in meta-analysis, H. pylori infection was associated with both non-cardia and cardia gastric cancer in Asian studies. The estimated population attributable fraction of H. pylori regarding gastric cancer incidence was about 76% in Korean. Cigarette smoking and alcohol drinking was associated with gastric cancer regardless of cardia and non-cardia gastric cancer. Cigarette smoking was estimated to be responsible for 28% of gastric cancer incidence in men and 2% in women. Obesity was risk factor for cardia gastric cancer but not non-cardia gastric cancer. This discrepancy between cardia and non-cardia gastric cancer was consistently shown in epidemiologic studies in Korea. Salt intake was also well-known risk factor of gastric cancer and prevalence of high sodium intake more than 2,000mg in Korean was 81.5%. For primary prevention of gastric cancer, eradication of H. pylori and life-style modification including no smoking, no alcohol drinking, weight control, and low sodium intake are important. Gastric endoscopy is recommended for secondary prevention of gastric cancer.
Aging ; Alcohol Drinking ; Asian Continental Ancestry Group ; Cardia ; Cohort Effect ; Economic Development ; Endoscopy ; Epidemiologic Studies ; Epidemiology ; Female ; Helicobacter pylori ; Humans ; Hygiene ; Incidence ; Korea ; Life Style ; Male ; Mortality ; Obesity ; Prevalence ; Primary Prevention ; Risk Factors ; Secondary Prevention ; Smoke ; Smoking ; Sodium ; Stomach Neoplasms

The 2019 hepatitis A outbreak has become increasingly prevalent among adults in Korea and is the largest outbreak since that in 2009–2010. The incidence in the current outbreak is highest among adults aged 35–44 years, corresponding to the peak incidence among those aged 25–34 years 10 years ago. This may indicate a cohort effect in the corresponding age group. Causes of these repeated outbreaks of hepatitis A in Korea are low level of immunity among adults, Korean food culture that consumes raw seafood such as salted clam and inadequate public health system. Among countermeasures, along with general infectious disease control measures including control of the infectious agent, infection spread, and host, urgent actions are needed to review the vaccination policy and establish an adequate public health system.
Adult ; Bivalvia ; Cohort Effect ; Communicable Diseases ; Disease Outbreaks ; Epidemiology ; Hepatitis A virus ; Hepatitis A ; Hepatitis ; Humans ; Immunization ; Incidence ; Korea ; Public Health ; Seafood ; Vaccination

No abstract available.
Cohort Effect ; Cohort Studies ; Female ; Humans ; Menarche

BACKGROUND: People who were born in different years, that is, different birth cohorts, grow in varying socio-historical and dynamic contexts, which result in differences in social dispositions and physical abilities. METHODS: This study used age-period-cohort analysis method to establish explanatory models on healthcare expenditure in Korea reflecting birth cohort factor using intrinsic estimator. Based on these models, we tried to investigate the effects of ageing population on future healthcare expenditure through simulation by scenarios. RESULTS: Coefficient of cohort effect was not as high as that of age effect, but greater than that of period effect. The cohort effect can be interpreted to show ‘healthy ageing’ phenomenon. Healthy ageing effect shows annual average decrease of −1.74% to 1.57% in healthcare expenditure. Controlling age, period, and birth cohort effects, pure demographic effect of population ageing due to increase in life expectancy shows annual average increase of 1.61%–1.80% in healthcare expenditure. CONCLUSION: First, since the influence of population factor itself on healthcare expenditure increase is not as big as expected. Second, ‘healthy ageing effect’ suggests that there is a need of paradigm shift to prevention centered-healthcare services. Third, forecasting of health expenditure needs to reflect social change factors by considering birth cohort effect.
Cohort Effect ; Cohort Studies ; Delivery of Health Care ; Forecasting ; Health Expenditures ; Korea ; Life Expectancy ; Methods ; Parturition ; Population Dynamics ; Social Change

OBJECTIVES: Although the nationwide inoculation rate of varicella vaccine was approximately 95% in Korean children recently, the number of notified varicella cases is unexpectedly continuously increasing till now. To suggest some hypotheses regarding this discrepancy, an age-period-cohort (APC) analysis as a descriptive epidemiology study was conducted for children residing in Jeju-do, Korea. METHODS: The raw data were obtained from the nationwide database for insurance claim of healthcare fee provided by the National Health Insurance Service, Korea. The selection criteria were children aged 2–13 years who visited any healthcare center due to varicella from 2005 to 2016 while residing in Jeju-do. After calculating the birth cohort-specific crude incidence rates by age and year, the intrinsic estimator method was used to perform the APC analysis. RESULTS: As the annual crude incidence rates decreased with increasing age between 2005 and 2016, the age and period effects also decreased. The intrinsic estimator coefficients suggesting the cohort effect shifted from positive to negative in 2011, the starting year of free varicella vaccine program in Jeju-do. CONCLUSIONS: The results suggested that inoculated varicella vaccines have preventive effects. However, further studies to evaluate waning immunity would be needed.
Chickenpox Vaccine ; Chickenpox* ; Child* ; Cohort Effect ; Delivery of Health Care ; Epidemiology ; Fees and Charges ; Humans ; Immunization Programs ; Immunization Schedule ; Incidence* ; Insurance ; Jeju-do* ; Korea* ; Measles-Mumps-Rubella Vaccine ; Methods ; National Health Programs ; Parturition ; Patient Selection ; Vaccines

OBJECTIVES: Although the nationwide inoculation rate of varicella vaccine was approximately 95% in Korean children recently, the number of notified varicella cases is unexpectedly continuously increasing till now. To suggest some hypotheses regarding this discrepancy, an age-period-cohort (APC) analysis as a descriptive epidemiology study was conducted for children residing in Jeju-do, Korea.METHODS: The raw data were obtained from the nationwide database for insurance claim of healthcare fee provided by the National Health Insurance Service, Korea. The selection criteria were children aged 2–13 years who visited any healthcare center due to varicella from 2005 to 2016 while residing in Jeju-do. After calculating the birth cohort-specific crude incidence rates by age and year, the intrinsic estimator method was used to perform the APC analysis.RESULTS: As the annual crude incidence rates decreased with increasing age between 2005 and 2016, the age and period effects also decreased. The intrinsic estimator coefficients suggesting the cohort effect shifted from positive to negative in 2011, the starting year of free varicella vaccine program in Jeju-do.CONCLUSIONS: The results suggested that inoculated varicella vaccines have preventive effects. However, further studies to evaluate waning immunity would be needed.
Chickenpox Vaccine ; Chickenpox ; Child ; Cohort Effect ; Delivery of Health Care ; Epidemiology ; Fees and Charges ; Humans ; Immunization Programs ; Immunization Schedule ; Incidence ; Insurance ; Jeju-do ; Korea ; Measles-Mumps-Rubella Vaccine ; Methods ; National Health Programs ; Parturition ; Patient Selection ; Vaccines

PURPOSE: This study was conducted to describe the trends and age-period-cohort effects on the incidence and mortality rate of cervical cancer in Korea. MATERIALS AND METHODS: The incidence and mortality rate of cervical cancer among ≥ 20-year-old women from 1993 to 2012 were obtained from the Korea Central Cancer Registry and the Korean Statistical Information Service. Age-standardized rates were calculated and Joinpoint regression was used to evaluate the trends in the incidence and mortality rate. Age-period-cohort analysis was performed to investigate the independent effects of age, period and cohort. RESULTS: The incidence of cervical cancer decreased from 32.8 per 100,000 in 1993 to 15.9 per 100,000 in 2012 (annual percent change [APC], –3.9%; 95% confidence interval [CI], –4.2% to –3.6%). The mortality rate decreased from 5.2 per 100,000 in 1993 to 2.1 per 100,000 in 2012 (APC, –4.8%; 95% CI, –5.1% to –4.4%); however, the incidence and mortality rates among young women (< 30 years old) increased. An age-period-cohort model of the incidence and mortality rate showed decreasing period effects between 1993 and 2008 and decreasing cohort effects between 1928 and 1973, while birth cohorts after 1973 exhibited slight increases in the incidence and mortality rate of cervical cancer. CONCLUSION: Recent decreases in the incidence and mortality rate of cervical cancer were due to decreases in the period and cohort effects, which reflect the implementation of a cancer screening program and changes in lifestyle. However, our findings also highlighted an increase in cohort effects on the incidence and mortality rate among young women born after 1973.
Cohort Effect ; Cohort Studies ; Early Detection of Cancer ; Female ; Humans ; Incidence* ; Information Services ; Korea* ; Life Style ; Mortality* ; Parturition ; Uterine Cervical Neoplasms* ; Young Adult

This study aims to provide a systematical introduction of age-period-cohort (APC) analysis to South Korean readers who are unfamiliar with this method (we provide an extended version of this study in Korean). As health data in South Korea has substantially accumulated, population-level studies that explore long-term trends of health status and health inequalities and identify macrosocial determinants of the trends are needed. Analyzing long-term trends requires to discern independent effects of age, period, and cohort using APC analysis. Most existing health and aging literature have used cross-sectional or short-term available panel data to identify age or period effects ignoring cohort effects. This under-use of APC analysis may be attributed to the identification (ID) problem caused by the perfect linear dependency across age, period, and cohort. This study explores recently developed three APC models to address the ID problem and adequately estimate the effects of A-P-C: intrinsic estimator-APC models for tabular age by period data; hierarchical cross-classified random effects models for repeated cross-sectional data; and hierarchical APC-growth curve models for accelerated longitudinal panel data. An analytic exemplar for each model was provided. APC analysis may contribute to identifying biological, historical, and socioeconomic determinants in long-term trends of health status and health inequalities as well as examining Korean's aging trajectories and temporal trends of period and cohort effects. For designing effective health policies that improve Korean population's health and reduce health inequalities, it is essential to understand independent effects of the three temporal factors by using the innovative APC models.
Aging ; Cohort Effect* ; Cohort Studies* ; Health Policy ; Korea ; Methods ; Socioeconomic Factors

This study aims to provide a systematical introduction of age-period-cohort (APC) analysis to South Korean readers who are unfamiliar with this method (we provide an extended version of this study in Korean). As health data in South Korea has substantially accumulated, population-level studies that explore long-term trends of health status and health inequalities and identify macrosocial determinants of the trends are needed. Analyzing long-term trends requires to discern independent effects of age, period, and cohort using APC analysis. Most existing health and aging literature have used cross-sectional or short-term available panel data to identify age or period effects ignoring cohort effects. This under-use of APC analysis may be attributed to the identification (ID) problem caused by the perfect linear dependency across age, period, and cohort. This study explores recently developed three APC models to address the ID problem and adequately estimate the effects of A-P-C: intrinsic estimator-APC models for tabular age by period data; hierarchical cross-classified random effects models for repeated cross-sectional data; and hierarchical APC-growth curve models for accelerated longitudinal panel data. An analytic exemplar for each model was provided. APC analysis may contribute to identifying biological, historical, and socioeconomic determinants in long-term trends of health status and health inequalities as well as examining Korean's aging trajectories and temporal trends of period and cohort effects. For designing effective health policies that improve Korean population's health and reduce health inequalities, it is essential to understand independent effects of the three temporal factors by using the innovative APC models.
Aging ; Cohort Effect ; Cohort Studies ; Health Policy ; Korea ; Methods ; Socioeconomic Factors