The unrealized potential: cohort effects and age-period-cohort analysis

Age-period-cohort analysis of smoking prevalence trends among career military personnel in South Korea

INTRODUCTION

This study evaluated smoking trends among career military personnel in South Korea. After a tobacco tax increase in 2015, the tobacco control program for career military personnel expanded significantly. This study explores long-term smoking trends among career military personnel through age-period-cohort (APC) analysis within the context of targeted tobacco control policies.

METHODS

This secondary data analysis utilized data from 12052 individuals aged 19--54 years, identified as career military personnel in the Korea Community Health Survey (KCHS) from 2008 to 2022. APC analysis with the intrinsic estimator (IE) method was conducted to address multicollinearity and accurately assess the contributions of age, period, and birth cohort to smoking prevalence.

RESULTS

Smoking prevalence significantly decreased among career military personnel, from 46.2% in 2008 to 34.1% in 2022. The highest prevalence of smoking was initially observed in the age group of 22-24 years. Although overall prevalence declined, a slight increase was observed in the age group of mid-30s to early 40s, suggesting that smoking behavior varied across age groups. A significant decrease occurred between 2014 and 2016, with individuals born in the 1970s exhibiting the highest smoking prevalence, and those born after 1980 demonstrating a notably lower smoking prevalence.

CONCLUSIONS

Although smoking prevalence has declined, the distinct age, period, and cohort characteristics of career military personnel necessitate tailored tobacco control policies that consider the various aspects of military life.

Divergence in smoking and drinking trends: Results from age-period-cohort analytical approach

BACKGROUND

Smoking has dropped substantially over time while alcohol consumption has increased. Understanding how smoking and drinking relate to age, time-period or birth cohorts may improve public health measures.

METHOD

The cross-sectional Continuous Household Survey in Northern Ireland provided bi-annual, household-level data on smoking and drinking from 1985 to 2015. An age-period-cohort approach was employed using 10-year age groups and 9 birth cohorts. A descriptive analysis of smoking and drinking by birth cohort was performed and supplemented by a joinpoint analysis. An Intrinsic Estimator model was used to examine behaviour patterns defined separately by age, time-period, and cohort.

RESULTS

Age effects showed that smoking and drinking peaked during adolescence and young adulthood (relative risk (RR) of age 25-34 vs. all ages: RR smoking = 1.59, RR drinking = 1.61, p < 0.001), followed by a progressive subsequent decline with age. Distinct secular trends were observed whereby smoking decreased over time but non-abstinence rates in relation to alcohol consumption increased substantially from 1985 to 2015. Cohort effects in smoking and drinking suggested that Generation X (born around 1961-1980) appeared to have a slightly higher likelihood of smoking and drinking but this converged with other cohorts over time.

CONCLUSION

The absence of similar policy efforts for alcohol as given to smoking may explain the divergence in secular trends of smoking and drinking. Targeting interventions towards adolescents and young adults may offer the best chance of reducing smoking and drinking prevalence. Cohort effects suggest the need for further research about the relationship between drinking and Northern Ireland's political history.

Trends in adult mortality rates in India, 1970 to 2018: age-period-cohort analysis

High premature adult deaths in developing countries are gaining attention, as recent studies show their increasing impact on overall mortality rates. This paper has twofold objectives: firstly, it investigates the long-term trends and patterns of adult mortality between 1970 and 2018 in India. Secondly, it attempts to detect age, period, and cohort (APC) effects on adult mortality decline over time. Data on age-specific mortality rates and disease-adjusted life years for adult age groups (15-59 years) were collected from the Sample Registration System and the Global Burden of Disease study, respectively. The trends in age-standardized mortality rates were presented graphically, and critical change points were highlighted using a change-point analysis. The intrinsic estimator model was applied to estimate the independent effects of APC on adult mortality. The findings revealed that adult mortality declined between 1970 and 2018 with multiple critical change points. The APC effects showed a notable decline in adult mortality during 2005-2018 and for the recent birth cohorts, 1980-2004. However, the rate of mortality declined slowly over time. Results also indicated that mortality started increasing from mid-adult ages and peaked in older adult ages due to the age effects and provided evidence of a rise in adult life loss due to non-communicable diseases in recent years. Overall, the study underscores the importance of implementing health policies aimed at reducing life loss in the most economically active ages that can have long-term negative implications for the country's economic growth.

The Trend of Chronic Diseases Among Older Koreans, 2004-2020: Age-Period-Cohort Analysis

OBJECTIVES

This study aimed to examine age, period, and cohort effects contributing to the prevalence of diabetes and hypertension among older Koreans. Additionally, it sought to investigate how sociodemographic characteristics interact with period and cohort effects to influence the disease prevalence.

METHODS

Using the 2004-2020 data from the National Survey of Older Koreans, a nationally representative sample of older adults aged 65 or older, hierarchical age-period-cohort cross-classified random effects models (HAPC-CCREMs) were employed to estimate separate age, period, and cohort components of the recent trends in diabetes and hypertension. Sociodemographic characteristics were tested for their interactions with period and cohort effects.

RESULTS

Significant period effects were observed, indicating a steady increase in the likelihood of being diagnosed with diabetes and hypertension over time. Age effects revealed a quadratic trend, with disease risks generally increasing with age, but the rate of increase diminishing at older ages. Cohort effects exhibited an inverted U-shaped pattern, with higher risks observed in the 1930s and early 1940s cohorts compared to earlier and later cohorts. Gender and educational attainment emerged as significant moderators. Women than men born in the early 1930s exhibited higher risks of diabetes and hypertension, whereas individuals with lower educational attainment showed a steadily increasing risk of hypertension over time.

DISCUSSION

The results underscore the complex interplay of age, period, and cohort effects in shaping disease prevalence among older Koreans. Our findings highlight the importance of considering historical context and sociodemographic factors in understanding disease trends and designing targeted interventions to mitigate health disparities.

Environmental asbestos exposure from nephrite jade mining and lung cancer

BACKGROUND

Nephrite is an asbestos mineral composed of tremolite and actinolite. Fengtian is a community where nephrite was mined between 1970 and 1980 and asbestos was mined between 1960 and 1985. The lung cancer risk to the surrounding community is unknown.

AIMS

To analyse the trend of lung cancer caused by environmental contamination from nephrite mining.

METHODS

We conducted a field survey of nephrite mines and tracked new cases of lung cancer from 1980 to 2019. We calculated the age-standardized incidence rates (ASIRs) and applied join-point regression to examine the lung cancer trend. We assessed the age effect, period effect, and birth cohort effect on lung cancer risk.

RESULTS

The nephrite mines were contaminated with chrysotile and tremolite/actinolite asbestos. A total of 278 new cases of lung cancer were reported during the study period. There was an apparent age effect and a slight period effect for lung cancer. After adjustment for the age and period effects, the birth cohort born between 1970 and 1980 during the period of nephrite mass production had the highest relative risk compared with other birth cohorts. The ASIR of lung cancer increased significantly from 1980 to 2010 (the annual percentage change = 6.8 %, 95 % CI: 4.0-9.7 %, P < 0.01) and then decreased 30 years after the cessation of nephrite jade mining.

CONCLUSION

Nephrite mining increases the risk of lung cancer in nearby communities.

Decrease in household secondhand smoking among Korean adolescents associated with smoke-free policies: grade-period-cohort and interrupted time series analyses

OBJECTIVES

Smoke-free areas have expanded and related campaigns have been implemented since 1995 in Korea. As a result, household secondhand smoke (SHS) exposure has decreased over the past 15 years. We assessed the cohort effect, the effect of a 2008 campaign on household SHS exposure, and the impact of a complete smoking ban in public places along with increased penalties, as implemented in December 2011.

METHODS

Nationally representative cross-sectional 15-wave survey data of Korean adolescents were used. The 810,516 participants were classified into 6 grade groups, 15 period groups, and 20 middle school admission cohorts. An age-period-cohort analysis, conducted with the intrinsic estimator method, was used to assess the cohort effect of household SHS exposure, and interrupted-time series analyses were conducted to evaluate the effects of the smoke-free policy and the campaign.

RESULTS

For cohorts who entered middle school from 2002 to 2008, the risk of household SHS exposure decreased among both boys and girls. Immediately after implementation of the smoke-free policy, the prevalence of household SHS exposure by period decreased significantly for boys (coefficient, -8.96; p<0.05) and non-significantly for girls (coefficient, -6.99; p=0.07). After the campaign, there was a significant decrease in household SHS exposure by cohort among boys, both immediately and post-intervention (coefficient, -4.84; p=0.03; coefficient, -1.22; p=0.02, respectively).

CONCLUSIONS

A school-admission-cohort effect was found on household SHS exposure among adolescents, which was associated with the smoke-free policy and the campaign. Anti-smoking interventions should be implemented consistently and simultaneously.

Secular trends in the incidence of major depressive disorder and dysthymia in China from 1990 to 2019

BACKGROUND

Depression is increasingly recognized as a worldwide serious, public health concern. A better understanding of depression is important for advancing its management and learning the difference between major depressive disorder (MDD) and dysthymia. Our aim is to conduct a concurrent analysis of the trends of both MDD and dysthymia in China.

METHODS

The data on depression from 1990 to 2019 were collected from the Global Burden of Disease Study 2019 (GBD 2019). To determine the average annual percent changes (AAPC) and relative risks (RRs), joinpoint regression and the age-period-cohort models were employed, respectively.

RESULTS

The incidence number of MDD and dysthymia continuously increased in China from 1990 to 2019, however, the age-standardized rates (ASR) had a decreasing trend in both men and women. The results from joinpoint regression showed that a declining trend was presented in young people (< 50 years) but an increased trend in the elderly (≥ 50 years) both in men and women, during 1990-2019. Age is the most influential factor for MDD and dysthymia. Age RRs for MDD incidence had an overall increasing trend with age. Period RR in MDD presented a U-shaped pattern, while Cohort RRs presented an inverted U-shaped pattern. On the other hand, RRs in dysthymia for period and cohort effects had no statistical significance, only the age effect presented an inverted U-shaped pattern.

CONCLUSIONS

The disparities in trends observed between MDD and dysthymia during the period of 1990-2019 indicated the significance of distinguishing between these two disorders. The age, period and cohort effects all had a greater impact on MDD than on dysthymia, and age effects presented different influential patterns in these two. To alleviate the burden of depressive disorders in China, proactive measures need to be implemented, with particular attention to the elderly population.

Descriptive Analysis of Gastric Cancer Mortality in Korea, 2000-2020

PURPOSE

This study aimed to examine secular trends, age-period-cohort effects, and geographical differences in gastric cancer (GC) mortality in Korea.

Materials and Methods

Using cause of death data from the Korean Statistical Information Service for GC from 2000 to 2020, we calculated average annual percentage changes (AAPCs) in the age-standardized mortality of GC in 17 cities and provinces through joinpoint regression. Decomposition of age, period, and cohort effects on GC mortality were elucidated by applying a log-linear model and an intrinsic estimate method. Spatial patterns and the degree of spatial clustering in 250 administrative regions were explored via Moran's I statistics. Stratification by sex was performed for all analyses.

RESULTS

The age-standardized mortality of GC per 100,000 persons declined from 29.0 in 2000 to 7.9 in 2020 (AAPC, -6.28%). Age-period-cohort analyses of GC mortality showed a downward trend among five-year age groups from age 20-89 years across five-year periods from 2005-2020 and five-year birth cohorts from 1920-2000. Overall, the younger birth cohort showed lower mortality rates than the older cohort within the same period. In 2020, clusters of high GC mortality were observed in the central area for men (Chungcheongbuk, Jeollabuk, Gyeongsangbuk, and Gyeongsangnam) and in the eastern area for women (Gyeongsangbuk).

CONCLUSION

This study identified a downward trend in GC mortality among men and women from 2000 to 2020 in Korea. This trend was mainly attributed to birth cohort rather than period effects. Spatial analysis showed high GC mortality in the Chungcheong and Gyeongsangbuk areas.

Recent increase in pertussis incidence in South Korea: An age-period-cohort analysis

OBJECTIVES

Pertussis or whooping cough—one of the most contagious diseases—is caused by the Gram-negative bacterium Bordetella pertussis. Despite a high vaccination rate, Korea recently experienced a resurgence of pertussis. This study explores patterns and possible explanations for this resurgence through an age-period-cohort analysis.

METHODS

Using secondary data from the infectious disease portal of the Korea Disease Control and Prevention Agency and the Korea Statistical Information Service of Statistics Korea, this study analyzed the incidence of pertussis in Korea to determine which factors contributed to the recent increase using an age-period-cohort model.

RESULTS

Analysis of the age effect indicated that the age group most vulnerable to pertussis was 0-year to 2-year-olds. Analysis of the period effect showed a sharp increase in the incidence rate after 2016. Analysis of the cohort effect showed a significant decrease in incidence beginning with the 1955 birth cohort, with the risk increasing again with the 2000s birth cohort.

CONCLUSIONS

Previous studies have suggested 3 main possible explanations for our results. First, the increased incidence rate can be attributed to contact rates. Second, the rate of immunity through natural exposure has decreased due to the low number of circulating pathogens, in turn affecting the trend of infection. Lastly, variations in pathogens may have also contributed to the increase in incidence. Given that the most significant increase in incidence was observed among infants younger than 1 year old, sufficient maternal immunity must be prioritized to provide passive immunity to newborns via the placenta.

Representative Sampling of the Via Assessment Suite for Adults

Character strengths have become a popular topic in personality research. A set of questionnaires has recently been developed as measures of character strengths: the VIA Inventory of Strengths-Revised, two 96-item short forms of that instrument, and two new measures called the Global Assessment of Character Strengths and Signature Strengths Survey. Collectively, these are referred to as the VIA Assessment Suite for Adults. Prior research has supported the reliability and validity of these measures. The current study extended those findings through a demographically stratified sample of 1,765 U.S. resident adults. Results indicated the scores were interchangeable across all three versions of the VIA-IS, irrespective of whether the items are all positively keyed or a mix of positive and negative items. In addition, the VIA-IS-R factor structure is also consistent with a previously identified three-factor model for the strengths. By freeing residual covariances, a model was developed for which adequate fit was replicable. This provided the foundation for demonstrating measurement invariance. The present study also explored differences in strengths across demographic categories and evaluated various approaches to identifying key (signature) strengths for the respondents. Recommendations on the use of the different instruments are provided.

Physical Performance in Older Cohorts: A Comparison of 81-Year-Old Swedish Men and Women Born Twelve Years Apart-Results from the Swedish Study "Good Aging in Skåne"

Materials and Methods

Birth cohorts of both sexes drawn from the Swedish study “Good Aging in Skåne” for the years 1920–22 and 1932–34 were compared. Walking, the step test, the chair stand test, and the handgrip strength test were used as proxies for the physical performance. The results were adjusted for lifestyle habits and common chronic geriatric diseases.

Results

Both men and women in the later-born cohort walked more quickly and completed the chair stand test faster, and women were also quicker in the step test. No significant differences were found in the grip test, in either the male or female cohorts. Discussion. Normative reference values for physical tests of subjects of different ages can be misleading unless cohort effects are considered. Furthermore, age-related trajectories can also be misinterpreted if cohort effects are neglected which, in the longer perspective, could affect health care planning.

Conclusion

Birth cohort effects should be considered when comparing walking speed, number of steps, chair stands, and the step test, in men and women of older age.

Community context, birth cohorts and childhood body mass index trajectories: Evidence from the China nutrition and health survey 1991-2011

Childhood overweight and obesity have shown an increase in recent birth cohorts. China has undergone rapid socioeconomic transitions accompanied by lifestyle changes that have profoundly affected the physical growth of children. Less empirical research has considered the role of community context on the cohort effects of children's body mass index (BMI) z-score trajectories. We used the mixed effect models for repeated measurements with restricted cubic spline to predict the BMI z-score trajectories in children aged 1-17 years, influenced by different birth cohorts and community context using data from the China Health and Nutrition Survey from 1991 to 2011, and stratified by sex. Results indicated that the mean of BMI z-scores of children aged 1-17 years have increased in the 2000s cohort. Community context contributed to significant differences in BMI z-score increase with age from middle childhood, and this trend of community inequalities divergences in middle childhood in recent birth cohorts. Therefore, to promote equitable growth for all children in China, policy interventions focusing on the community context may have far-reaching effects on the health of children and adolescents.

Cancer Risk Studies and Priority Areas for Cancer Risk Appraisal in Uganda

Background

Research into aetiologies and prevention of the commonest cancers and implementation of primary and secondary prevention can reduce cancer risk and improve quality of life. Moreover, monitoring the prevalence of cancer risk factors in a specific population helps guide cancer prevention and early detection efforts and national cancer control programming.

Objective

This article aims to provide the scope and findings of cancer risk studies conducted in Uganda to guide researchers, health-care professionals, and policymakers.

Methods

Between November 2019 to January 2020, we searched peer-reviewed published articles in Pubmed, EMBASE and Cochrane Library (Cochrane central register of controlled trials-CENTRAL). We followed the recommendation of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses - the PRISMA. The primary focus was to identify cancer risk and prevention studies conducted in Uganda and published in peer-reviewed journals from January 2000 and January 2020. We used key Boolean search terms with their associated database strings.

Results

We identified 416 articles, screened 269 non-duplicate articles and obtained 77 full-text articles for review. Out of the 77 studies, we identified one (1%) randomized trial, two (2.5%) retrospective cohort studies and 14 (18%) case-control studies, 46 (60%) cross-sectional studies, five (6.4%) ecological studies, three panel studies (4%) and six (8%) qualitative studies. Cervical cancer was the most studied type of cancer in Uganda (23.4%, n = 18 studies), followed by lymphomas - both Hodgkin and Non-Hodgkin sub-types (20.7%), n = 16 studies) and breast cancer (15.6%, n = 12 studies). In lymphoma studies, Burkitt lymphoma was the most studied type of lymphoma (76%, n = 13 studies). The studies concentrated on specific cancer risk awareness, risk perceptions, attitudes, uptake of screening, uptake of human papillomavirus vaccination, the prevalence of some of the known cancer risk factors and obstacles to accessing screening services.

Conclusion

The unmet need for comprehensive cancer risk and prevention studies is enormous in Uganda. Future studies need to comprehensively investigate the known and putative cancer risk factors and prioritize the application of the higher-hierarchy evidence-generating epidemiological studies to guide planning of the national cancer control program.

Age-stratified anti-tuberculosis drug resistance profiles in South Korea: a multicenter retrospective study

BACKGROUND

The emergence of drug-resistant tuberculosis (DR-TB) is a major healthcare concern worldwide. Here, we analyzed age-related trends in DR-TB rates in South Korea.

METHODS

Drug susceptibility test results were collected from patients with culture-confirmed TB between 2015 and 2018 from eight university-affiliated hospitals. Patients were divided into three subgroups: younger (15-34 years), middle (35-59 years), and older (≥60 years) to compare drug-resistance patterns. To evaluate trends in age-stratified drug-resistance, chi-square test for linear trends was performed.

RESULTS

Among enrolled native patients aged ≥15 years, 4.1% (179/4417), 1.2% (53/4417) and 7.2% (316/4417) were multidrug-resistant TB (MDR-TB), rifampicin-mono-resistant TB (RR-TB), and isoniazid-mono-resistant TB (Hr-TB), respectively. Proportions of Hr-TB cases were 5.4% (40/734), 7.2% (114/1593), and 7.8% (162/2090) in the younger, middle and older age groups, respectively. MDR/RR-TB case rates decreased significantly with age from 8.6% (63/734) in younger age group to 3.3% (68/2090) in older age group. Fluoroquinolone resistance was highest among second-line drugs, and there were no differences in resistance to fluoroquinolones and second-line injectable drugs among the three age groups.

CONCLUSIONS

The number of MDR/RR-TB cases was highest in young patients. Effective public health interventions should include increased focus on rifampicin resistance in young patients.

Latent tuberculosis infection screening and treatment in congregate settings (TB FREE COREA): protocol for a prospective observational study in Korea

INTRODUCTION

South Korea regards tuberculosis (TB) incidence in congregate settings as a serious problem. To this end, systematic latent TB infection (LTBI) diagnosis and treatment were provided to approximately 1.2 million individuals in high-risk congregate settings.

METHODS AND ANALYSIS

We designed a prospective cohort study of individuals tested for LTBI, based on the data collected on all persons screened for LTBI as part of the 2017 congregate settings programme in South Korea. Four types of databases are kept: LTBI screening database (personal information and LTBI test results), national health information (NHI) database (socio-demographic data and comorbidities), public healthcare information system (PHIS) database, and the Korean national TB surveillance system database (TB outcomes). Information regarding LTBI treatment at private hospitals and public health centres is collected from NHI and PHIS databases, respectively. The screening data are cleaned, duplicates are removed, and, where appropriate, re-coded to analyse specific exposures and outcomes. The primary objective is to compare the number of active TB cases prevented within 2 years between participants undergoing treatment and not undergoing treatment in the LTBI screening programme in congregate settings. Cascade of care for LTBI diagnosis and treatment will be evaluated among those with a positive LTBI test result. A Cox proportional hazards model will be applied to determine the risk factors for developing active TB.

ETHICS AND DISSEMINATION

The protocol is approved by the institutional review boards of Incheon St. Mary's Hospital, the Catholic University of Korea. Study results will be disseminated through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

KCT0003905.

Time Trends for Prostate Cancer Incidence from 2003 to 2013 in South Korea: An Age-Period-Cohort Analysis

PURPOSE

Prostate cancer (PCa) incidence is affected by aging phenomenon and performance of screening test. In United States, PCa incidence is affected by period effect of U.S. Preventive Services Task Force (USPSTF) recommendation. However, no study has reported the effect of USPSTF recommendation or aging phenomenon on PCa incidence in South Korea. Thus, the objective of this study was to investigate effects of age, period, and birth cohort on PCa incidence using age-period-cohort analysis.

Materials and Methods

Annual report of cancer statistics between 2003 and 2013 from National Health Insurance Service (NHIS) in South Korea for the number of PCa patients and Korean Statistical Information Service (KOSIS) data between 2003 and 2013 from national statistics in South Korea for the number of Korean male population were used. Age-period-cohort models were used to investigate effects of age, period, and birth cohort on PCa incidence.

RESULTS

Overall PCa incidence in South Korea was increased 8.8% in annual percentage (95% confidential interval, 6.5 to 11.2; p < 0.001). It showed an increasing pattern from 2003 to 2011 but a decreasing pattern from 2011 to 2013. Age increased the risk of PCa incidence. However, the speed of increase was slower with increasing age. PCa incidence was increased 1.4 times in 2008 compared to that in 2003 or 2013. Regarding cohort effect, the risk of PCa incidence started to increase from 1958 cohort.

CONCLUSION

PCa incidence was affected by period of specific year. There was a positive cohort effect on PCa incidence associated with age structural change.

Relationship between incidence and prevalence in psychotic disorders: An incidence-prevalence-mortality model

OBJECTIVES

Incidence-prevalence-mortality (IPM) models have been developped to estimate incidence or prevalence when one of these two measures is unavailable. We aimed to test the consistency of an IPM model of psychotic disorders on a recent incidence-prevalence couple dataset and to identify potential causes of inconsistency by applying the model to (a) the whole population, (b) female and male subgroups, (c) migrant subgroups, and (d) psychotic disorders with age at onset (AAO) between 18 and 24 (18-24 AAO).

METHODS

We modelled prevalence (MP) using incidence data and the expected mortality and remission values. We then compared the MP to the observed prevalence (OP).

RESULTS

In the whole population, the model significantly underestimated the prevalence (MP = 3.30, 95% CI [2.97, 3.66]; OP = 4.98, 95% CI [4.58, 5.41]). The results were similar for the two genders. In the migrants group, results were in the opposite direction, the model significantly overestimating the prevalence. Finally, in the 18-24 AAO subgroup, the model performed well, with OP and MP not significantly different.

CONCLUSION

These results suggest that standard IPM models do not perform well for psychotic disorders and more complex models taking into account the heterogeneity of the sample (in terms of remission, mortality, population movements, etc.) need to be developed.