Age, Period And Cohort Research Articles

Time trends in the burden of autoimmune diseases across the BRICS: an age–period–cohort analysis for the GBD 2019

BackgroundThis study aims to evaluate the long-term trend of prevalence and DALY (disability-adjusted life-year) rate on the age, period and cohort (APC) of the BRICS (Brazil, Russia, India, China and...

Age, period and cohort effects on gastric cancer mortality in Spain, 1980-2021.

this study aimed to evaluate the effects of age, time period and cohort (A-P-C) on gastric cancer (GC) mortality in Spain from 1980 to 2021. an ecological trend study was performed (with aggregated data obtained from the Spanish National Statistics Institute (INE). Joinpoint regression software was used to estimate rates by sex and age group (< 35, 35-64, > 64 years) and mortality trends. The National Cancer Institute A-P-C tools were used to assess the effects of age, time of death and birth cohort. GC mortality rates in Spain decreased significantly in both sexes. In the under-35 age group, rates were stable after an initial significant decline. In the 35-64 age group, the decline was more pronounced in males than in females. In the 65+ age group, rates fell significantly for both sexes, but more so for females than for males. The net drift and local drift also showed significant decreases across all age groups from 24 years onwards. GC mortality rates increased with age and decreased with calendar time and successive birth cohorts, regardless of sex. The ratio of age-specific rates between males and females increased with age, and birth cohort relative risk estimates followed a steady downward trend until the mid-1970s, after which the decline stabilized. The relative risk decreased for both sexes, with a more pronounced decrease in males. GC mortality rates in Spain have been decreasing over time and across successive birth cohorts, with a stabilizing trend observed for those under 35 years of age.

Age-period-cohort modelling of type 1 diabetes incidence rates among children included in the EURODIAB 25-year follow-up study.

Specific patterns in incidence may reveal environmental explanations for type 1 diabetes incidence. We aimed to study type 1 diabetes incidence in European childhood populations to assess whether an increase could be attributed to either period or cohort effects. Nineteen EURODIAB centres provided single year incidence data for ages 0-14 in the 25-year period 1989-2013. Case counts and person years were classified by age, period and cohort (APC) in 1-year classes. APC Poisson regression models of rates were fitted using restricted cubic splines for age, period and cohort per centre and sex. Joint models were fitted for all centres and sexes, to find a parsimonious model. A total of 57,487 cases were included. In ten and seven of the 19 centres the APC models showed evidence of nonlinear cohort effects or period effects, respectively, in one or both sexes and indications of sex-specific age effects. Models showed a positive linear increase ranging from approximately 0.6 to 6.6%/year. Centres with low incidence rates showed the highest overall increase. A final joint model showed incidence peak at age 11.6 and 12.6 for girls and boys, respectively, and the rate-ratio was according to sex below 1 in ages 5-12. There was reasonable evidence for similar age-specific type 1 diabetes incidence rates across the EURODIAB population and peaks at a younger age for girls than boys. Cohort effects showed nonlinearity but varied between centres and the model did not contribute convincingly to identification of environmental causes of the increase.

Are young Australians turning away from democracy?

ABSTRACT In most advanced democracies, the decline in electoral turnout has been disproportionately concentrated amongst young people. This study investigates whether young Australians are turning away from the principles and processes of democracy. If so, it further enquires which of the three highly collinear time effects – age, period and cohort (APC) – best explains youth disengagement. Existing works, which focus mostly on generational effects, fail to control for the confounding age and period effects. Using survey data from 2001 to 2019 in the Australian Election Study (AES) and applying multilevel models, this study disentangles the three-time effects. The findings suggest that young Australians are no different from older people and older cohorts in their commitment to principles and both traditional and contemporary (online) processes of democracy. Instead, period effects – that is, short-term political, economic and social context – best explain democratic attitudes and behaviours in Australia.

Trends in mortality rates for oral and oropharyngeal cancer in Spain, 1979-2018.

To analyse mortality rate trends in Spain for oral cavity and oropharyngeal cancer (OCOPC) from 1979 to 2018, evaluating differences between oral cavity cancer (OCC) and oropharyngeal cancer (OPC). Death certificates and mid-year population data were collected from the Spanish National Statistics Institute. Age-standardized mortality rates were calculated using the direct method. Joinpoint regressions were used to identify significant changes in mortality trends. Independent effects of age, period and cohort (APC) were estimated. A total of 52,057 deaths were registered from OCOPC, 38,988 from OCC and 13,069 from OPC between 1979 and 2018. While OCC mortality rates declined, OCOPC rates increased slightly and OPC significantly. OCC and OPC mortality reached their highest values between 1979 and 1992, when OCC rates began to decrease in males and OPC levelled off until 2018. Lip cancer suffered the highest drop. APC models showed a mortality increase in males and females from 40 to 45 and 50 to 55years of age, respectively. Favourable OCC mortality trends was plausibly influenced by decreased tobacco/alcohol consumption, while OPC rise was probably associated with increased human papillomavirus infection. The importance of closely monitoring these cancers by age group, sex and location, and continuing with preventive measures against known risk factors, is highlighted.

Cutaneous malignant melanoma mortality in Spain from 1979 to 2018. Trends and new perspectives in the immunotherapy era.

Recent studies suggest that cutaneous melanoma mortality rates in Spain are stabilizing and even decreasing in younger cohorts. To analyse mortality rates of melanoma from the last 40years, focusing on changes related with the development of new therapeutic approaches. Death records and mid-year population data were collected from the National Statistics Institute. By using the direct method, age-standardized mortality rates were calculated for overall population and for each sex and age group. Significant changes in mortality trends were identified by Joinpoint regressions. The independent effects of age, period and cohort (APC) and potential years of life lost (PYLL) due to melanoma were also analysed. Age-standardized melanoma mortality rates rose in Spain from 0.78 to 2.13 deaths per 100000 from the first to the last quinquennium of the study (1979-1983 to 2014-2018) for the overall population. After a marked increase until 1995, mortality rates levelled off. Following this stabilization, from 2015 to 2018 there was a decrease in mortality rates for the overall population (average annual per cent change (AAPC): -4.3, not significant), more accused in males over 64years old (yo). A period effect was observed from the beginning of 21st century, with mortality rates dropping to date. There is a decrease in melanoma mortality rates from 2015 in all age groups that confirms previous trends in mortality in younger cohorts. Improvement in diagnosis and development of new therapies for advanced melanoma may have a crucial role in this event. Close monitoring of melanoma mortality rates is necessary to confirm these trends.

Influence of birth cohort, age and period on suicide mortality rate in Turkey, 1983-2013.

This study is designed to evaluate the potential effects of age, period and cohort (APC) on trends in suicide between 1983 and 2013 in Turkey. Mortality data were obtained from the Turkish Statistical Institute. The data were grouped into seven age groups, four periods and ten birth cohorts. A nonlinear regression model was estimated for both sexes. The effects of age, period and cohort were parameterized using natural spline smoothing functions. There were 61,795 deaths recorded as suicides during the investigated time period, where 64.5% occurred in males (n = 39,862) and 35.5% in females (n = 21,933). There is an upward trend in mortality by age until the end of the study period for males and females. Age effect is decreased until the forties, kept decreasing during the middle ages, and sharply increased after the sixties. The death rates for females declined from 1999 until the end of the study period. For males, the death rates increased until the end of the study period. If the current trends continue, it can be expected that these effects will continue to reduce female mortality and increase male mortality. Future studies on suicide, strongly focused on specific factors attributed to period effects, are needed in Turkey.

Long-term care preference among Japanese older adults: differences by age, period and cohort

AbstractThis study examined the differences in the preference for long-term care (LTC) by age, period and cohort (A-P-C) in Japanese older adults through repeated cross-sectional surveys from 1998 – before the establishment of LTC insurance – to 2016, in a suburban city of metropolitan Tokyo. We analysed the direct effects of A-P-C on the preference for LTC, as well as the interaction effects of A-P-C on preference by gender, family structure and activities of daily living. Data were obtained at six time-points using repeated cross-sectional surveys for people aged 65 and older; surveys were conducted in 1998, 2002, 2004, 2010, 2013 and 2016. The preference for LTC was composed of three categories: informal care, community LTC services (CLTCS) and institutional LTC services (ILTCS). The cross-classified random-effect model was used to specify A-P-C effects. Informal care, CLITCS, ILTCS and other/no answer composed 35, 23, 33 and 9 per cent of preferences, respectively. In terms of the period effect, while there was an increase in levels of preference for CLTC between 1998 and 2010 as compared to informal care, the levels of preference were almost identical after 2010. In terms of the age effect, younger participants were more likely to prefer CLTCS and ILTCS over informal care. Moreover, the age influence was stronger in females and respondents who lived alone. We did not observe a cohort effect for preference. This study suggests that there are gaps by period and age between the preference for LTC services and the actual LTC use in Japanese older adults, and as a result, the use of actual LTC services cannot fully reflect the intentions and preference for LTC in them.

Mortality due to acute myocardial infarction in Brazil and its geographical regions: analyzing the effect of age-period-cohort.

The objective of this study was to analyze the effect of age-period and cohort (APC) of birth on mortality for acute myocardial infarction in Brazil and its geographic regions, according to sex in the period from 1980 to 2009. The data was extracted from the Mortality Information System and was corrected and adjusted by means of proportional redistribution of records with sex and age ignored, ill-defined causes, and corrections were made based on the death sub-register. The APC was calculated using the Poisson regression model with estimable functions. The APC analysis on both sexes and in all regions of the country showed gradual reductions in the risk of death in birth cohorts from the decade of the 1940s, except in the Northeast. In this region, there have been progressive increases in the risk of death from the late 1940s for both sexes. This was up until the 1950s for men and the 1960s for women. It was concluded that the observed differences in the risk of death in Brazilian regions is the result of socio-economic inequalities and poor access to health services within the Brazilian territory, favoring early mortality for this cause especially in poorer areas.

The use of a chronic disease and risk factor surveillance system to determine the age, period and cohort effects on the prevalence of obesity and diabetes in South Australian adults--2003-2013.

BackgroundAge, period and cohort (APC) analyses, using representative, population-based descriptive data, provide additional understanding behind increased prevalence rates.MethodsData on obesity and diabetes from the South Australian (SA) monthly chronic disease and risk factor surveillance system from July 2002 to December 2013 (n = 59,025) were used. Age was the self-reported age of the respondent at the time of the interview. Period was the year of the interview and cohort was age subtracted from the survey year. Cohort years were 1905 to 1995. All variables were treated as continuous. The age-sex standardised prevalence for obesity and diabetes was calculated using the Australia 2011 census. The APC models were constructed with ‘‘apcfit’’ in Stata.ResultsThe age-sex standardised prevalence of obesity and diabetes increased in 2002-2013 from 18.6% to 24.1% and from 6.2% to 7.9%. The peak age for obesity was approximately 70 years with a steady increasing rate from 20 to 70 years of age. The peak age for diabetes was approximately 80 years. There were strong cohort effects and no period effects for both obesity and diabetes. The magnitude of the cohort effect is much more pronounced for obesity than for diabetes.ConclusionThe APC analyses showed a higher than expected peak age for both obesity and diabetes, strong cohort effects with an acceleration of risk after 1960s for obesity and after 1940s for diabetes, and no period effects. By simultaneously considering the effects of age, period and cohort we have provided additional evidence for effective public health interventions.

Current practice in the modelling of age, period and cohort effects with panel data: a commentary on Tawfik et al. (2012), Clarke et al. (2009), and McCulloch (2012)

This comment assesses how age, period and cohort (APC) effects are modelled with panel data in the social sciences. It considers variations on a 2-level multilevel model which has been used to show apparent evidence for simultaneous APC effects. We show that such an interpretation is often misleading, and that the formulation and interpretation of these models requires a better understanding of APC effects and the exact collinearity present between them. This interpretation must draw on theory to justify the claims that are made. By comparing two papers which over-interpret such a model, and another that in our view interprets it appropriately, we outline best practice for researchers aiming to use panel datasets to find APC effects, with an understanding that it is impossible for any statistical model to find and separate all three effects.

Consumer cohorts and purchases of nonalcoholic beverages

Age, period and cohort (APC) variables are included in a demand system that is used to estimate Norwegian purchases of nonalcoholic beverages. To take account of censoring, a two-step method is used. In the first step, the probabilities of purchasing milk, carbonated soft drinks and other soft drinks are estimated by probit models. The APC variables are highly significant. Older cohorts have higher probabilities of purchasing milk and lower probabilities of purchasing carbonated soft drinks than younger cohorts. In the second step, the probability density functions and the cumulative density function are used to correct for censoring. In the corrected demand system, there are positive cohort and negative age effects for milk. These effects suggest that the replacement of older by younger cohorts, in an increasingly older population, will result in reduced per capita purchases of milk. For carbonated soft drinks, there are no cohort or negative age effects, while there are positive age but no cohort effects for other soft drinks.

An age-period-cohort approach to analyzing trends in suicide in Quebec between 1950 and 2009.

Suicide rates in Quebec over the second half of the 20th century show a wide range of variation depending on age and time period. However, few studies have verified the presence of a cohort effect affecting trends in Quebec suicide rates. This study is designed to evaluate the potential effects of age, period and cohort (APC) on trends in suicide between 1950 and 2009 in Quebec. For these APC analyses, we used a multiphase approach combining a graphical inspection followed by an analysis that isolates the cohort effect from age and period effects (linear regression of the residuals from a median polish of the rates). The graphical inspection of trends in rates points to combined effects of age, period and cohort among both men and women. However, the median polish analysis attributes primary importance to period effects, followed by age effects, but also shows weak cohort effects that are significant only among men born between 1950 and 1979. The variation in Quebec suicide rates appears to be primarily a reflection of period, age and, to a lesser degree, birth cohort. Thus, in addition to sex, selection of risk groups should be based more on age and time period than on birth cohort.

Trends in lung cancer mortality in Brazil from the 1980s into the early 21st century: age-period-cohort analysis

The aim of this study was to describe the pattern of trends in lung cancer mortality in Brazil and identify the effects of the factors age, period and cohort (APC) on mortality rates. A time series study was conducted using secondary population-based data. Lung cancer mortality rates by sex were calculated for the period 1980 to 2007. APC models were adjusted to identify the influence of age, period and cohort effects on rates. Lung cancer mortality rates are significantly higher among men. Specific rates for men over the age of 64 and for women of all ages are increasing. There was a greater increase of adjusted rates among women. With respect to the age effect, mortality risk increases with age starting with the earliest age groups. With regard to the cohort effect, there is a lesser risk of mortality among men born after 1950 and an increasing risk across all cohorts among women. The results regarding younger generations indicate that present trends are likely to continue. The cohort effect among women suggests an increasing trend in mortality rates, whereas a decrease in rates among men under the age of 65 suggests that this trend will continue. These trends reflect tobacco control measures adopted since 1986.

Age, Period and Cohort Analysis of Light and Binge Drinking in Finland, 1968-2008

To analyse the effects of age, period and cohort (APC) on light and binge drinking in the general population of Finland over the past 40 years. All analyses were based on six Drinking Habits Surveys between 1968 and 2008 of representative samples of the Finnish population aged between 15 and 69 (n = 16,400). The number of drinking occasions per year involving 1-2 drinks (light) and 4+ or 6+ drinks (binges) was used as a dependent variable in APC modelling. Descriptive cohort profiles and negative binomial models were used to assess the effects of APC. Descriptive cohort profiles differed for light and binge drinking. No substantial differences were found across cohort profiles for light drinking, while APC modelling predicted declining cohort and increasing period effects. Differences between cohorts were found for binge drinking, with predictions of slightly declining or increasing period and increasing cohort effects. Light drinking has increased over time for each cohort, with no substantial differences between cohort profiles. Binge drinking has increased with more recent cohorts and there are distinct differences between cohort profiles, especially among women.

An age and period reconstruction of the HIV epidemic in Italy.

The majority of AIDS cases in Italy are among intravenous drug users (68%) and homosexual men. An age, period and cohort (APC) model is presented and used to reconstruct the HIV epidemics in Italy. Projections of AIDS-related conditions (ARC) and AIDS cases are attempted based on a hypothesis of minima and an endemic hypothesis. The model is a generalization of the usual back-calculation method which considers age, competitive mortality, susceptible population and therapy effects. Estimates of the HIV epidemic in Italy are obtained using Italian AIDS counts (corrected for delay in reporting), and an incubation time distribution (estimated from data of an Italian cohort), which was found to be dependent on the age at infection. The impact of AZT therapy, introduced in Italy in mid1987, is evaluated using a modification of the incubation time distribution dependent on period of infection. The estimated number of new infections in Italy declined after 1987, although the number of new AIDS cases has continued to rise, albeit less steeply in recent years. When delay in the progression to AIDS due to therapy is taken into account, the estimated number of people infected in mid1990 increases from 52,000 to 67,000, with approximately 12% of subjects already in the ARC stage. The age at maximum risk of infection is 25 years in males and 23 years in females. Using a hypothesis of no more HIV infections after 1990, AIDS counts would be still rising in Italy up to 1993 as a result of past infections and of the long incubation period.