This study identifies the period and cohort effects on the decreasing mortality trend of cancer of the uterine cervix and of the uterus, part unspecified, in the state of Minas Gerais, Brazil, during the period 1980-2005. 11,243 cases were included. A non-parametric method was used to calculate Z statistics and p-values. The cohorts were assessed one by one and also in blocks of three, so as to allow for a larger number of comparisons to be made. Greater than expected mortality reduction was observed for the cohort blocks of women born in 1913-1920; 1927-1936; 1937-1946; 1949-1956; 1963-1970; and 1969-1976. For the 1901-1908 and 1921-1928 cohort blocks a smaller than expected mortality decrease was found. As for period effect, we found a greater than expected reduction for the 2000-2001 period, in comparison with the previous one. The study suggests the existence of a significant cohort effect on mortality due to cancer of the uterine cervix in the study population, and such results have been placed in their social and political contexts.

STUDY OBJECTIVE--The aim was to provide insights in the spread of the smoking epidemic and eventual progress against cigarette smoking in West Germany. DESIGN--This was a retrospective birth cohort analysis based on a cross sectional national survey. SETTING--The survey was conducted in 1987 by the Ministry of Youth, Family and Health in order to identify priorities for health policy and promotion. The target population were all residents of German nationality above the age of 14 years. STUDY POPULATION--1721 men and women of the birth cohorts 1911-20, 1921-30, 1931-40, 1941-50, 1951-60, and 1961-70 were included in this analysis (65.7% overall response rate). MEASUREMENTS AND MAIN RESULTS--The participants were asked for their detailed life time history of cigarette smoking in a personal interview. This information was used to calculate and plot historical smoker prevalences by sex, level of school education, birth cohort, and calendar year after correcting for differential survival of smokers and non-smokers. In men, smoking prevalences increased slowly from birth cohort to birth cohort and reached a maximum of more than 70% in the 1941-50 cohort in the early 1970s. While smoker prevalences were considerably lower in the two youngest birth cohorts among better educated men...

A history of cohort analysis has been given, and it has been pointed out that the bulk of the literature on the subject has dealt with concepts that assume either that graduation and possibly extrapolation are desirable, preferably in conformity with some formula expressing what is implicitly accepted as a "law of mortality", or that, whether or not a fixed pattern of mortality exists, the intensity of mortality risk is largely determined in early life. The view is advanced that either concept alone, is, or both concepts together are, inadequate and may lead to an improper assessment of the nature-nurture complex, since environment and therapeutic measures are constantly changing. The plea is made for the technique of cohort analysis to be used as a narrative or historical technique, and for a synthesis of knowledge derived from social history, medical history, and cohort analysis to be made to interpret the narrative. The effects of a changing rate on the mortality pattern as depicted by date-contour analysis and cohort analysis are outlined and the danger of basing biological theories on the mortality pattern revealed by date-contour analysis alone is indicated. This point is illustrated by reference to a recent theory that has been based on such an analysis.

It is often necessary to include WHO group 5 drugs in the treatment of extensively drug-resistant tuberculosis (XDR-TB) and fluoroquinolone-resistant multidrug-resistant tuberculosis (MDR-TB). As clinical evidence about the use of group 5 drugs is scarce, we conducted a systematic review using published individual patient data. We searched PubMed and OvidSP through 7 April 2013 for publications in English to assemble a cohort with fluoroquinolone-resistant MDR-TB treated with group 5 drugs. Favorable outcome was defined as sputum culture conversion, cure, or treatment completion in the absence of death, default, treatment failure, or relapse. A cohort of 194 patients was assembled from 20 articles involving 12 geographical regions. In descending order of frequency, linezolid was used in treatment of 162 (84%) patients, macrolides in 84 (43%), clofazimine in 65 (34%), amoxicillin with clavulanate in 56 (29%), thioridazine in 18 (9%), carbapenem in 16 (8%), and high-dose isoniazid in 16 (8%). Cohort analysis with robust Poisson regression models and random-effects meta-analysis similarly suggested that linezolid use significantly increased the probability (95% confidence interval) of favorable outcome by 57% (10% to 124%) and 55% (10% to 121%)...

Introduction. There is an established fact that Asian breast cancer patients are, on average, younger than their European counterparts. This study aimed to utilize the data from the Cancer Incidence in Five Continents I through XIII (published by the International Agency for Research on Cancer) to examine what contributes to the younger age at onset in the Asian population. Material and Methods. Data (number of breast cancer cases and corresponding population figures) for 29 registries in Europe and 9 registries in Asia for the period of 1953–2002 was accessioned and pooled to form two distinct populations, Asia and Europe. The age specific rates were defined and analyzed cross-sectionally (period wise) and longitudinally (cohort wise). The magnitude and the pattern of age specific rates were analyzed using the age-period-cohort analysis. The constrained generalized linear model with a priority assumption of cohort effect as contributing factor to changing rates was used to analyze the data. Result. During the last 50 years, the rate of breast cancer increased for both populations with an estimated annual percent change of 1.03% (with 95% CI of 1.029, 1.031) for Asia and 1.016% (95% CI of 1.015, 1.017) for Europe. There were stronger cohort effects in the magnitude of rates among the Asian population compared to the European population. The cohort effects...

Data from the 1986, 1991 and 1996 Censuses is used to conduct a cohort analysis of the probability of employment and participating in the labour force for indigenous and non-indigenous males and females. Single-year age cohorts are used in the first ever longitudinal regression analysis of indigenous labour force status. The other contribution of this paper is to analyse labour market processes at an aggregate level by using census information on the entire Australian population (separately for indigenous and other Australians). By distinguishing aggregate and micro-labour market processes the analysis details what happens to the population, on average, as the level of educational attainment increases.

This paper demonstrates that factors which are related to the probability of employment and participating in the labour force for the indigenous population differ from those for the non-indigenous population. At an aggregate level, it is found that the increasing educational attainment of indigenous Australians which occurred between 1986 and 1996 has not resulted in the anticipated improvements in employment levels. In contrast, employment was found to be positively related to increases in educational attainment in the non-indigenous population. Marital status is found to be the most important determinant of the probability of employment and participating in the labour force for indigenous people...

The myth of equality in Australian society is clearly exposed by the large income gap between indigenous and other Australians. Data from the 1986, 1991 and 1996 Censuses is used to conduct a cohort analysis of the income distributions for indigenous and non-indigenous males and females. Single-year age cohorts are used in the first longitudinal regression analysis of indigenous income. Trends in relative income deprivation are identified.; yes

Background: The cost of dental care may be a barrier to regular dental attendance with the proportion of the Australian population avoiding or delaying care due to cost increasing since 1994. This paper explores the extent to which age, period and cohort factors have contributed to the variation in avoiding or delaying visiting a dentist because of cost. Methods: Data were obtained from four national dental telephone interview surveys of Australian residents aged five years and over conducted in 1994, 1999, 2004 and 2010 (response rates 48% - 72%). The trend in the percentage of persons avoiding or delaying visiting a dentist because of cost was analysed by means of a standard cohort table and more formal age-period-cohort analyses using a nested models framework. Results: There was an overall increase in the proportion of people avoiding or delaying visiting a dentist indicating the presence of period effects. Financial barriers were also associated with age such that the likelihood of avoiding because of cost was highest for those in their mid-late twenties and lowest in both children and older adults. Cohort effects were also present although the pattern of effects differed between cohorts. Conclusion: The findings of this study suggest that...

BACKGROUND: Understanding dentists' capacity to supply dental services over time is a key element in the process of planning for the future. The aim was to identify time trends and estimate age, period and cohort effects in patients' visits supplied per dentist per year. METHODS: Mailed questionnaires were collected from a random sample of Australian private general practice dentists. The response rates were 73%, 75%, 74%, 71%, 76% and 67% in 1983, 1988, 1993, 1998, 2003 and 2009, respectively. The time trends in the mean number of patient visits supplied per dentist per year (PPY) was described by using a standard cohort table and age-period-cohort analyses applying a nested general linear regression models approach. RESULTS: The mean number of PPY decreased across most age groups of dentists over the time of study. The age-period model showed that younger dentists (20-29 years) and older dentists (65-74 and 80-84 years) had lower PPY than middle-aged dentists, and the age-cohort model showed higher PPY among earlier cohorts, and lower PPY among more recent cohorts. CONCLUSION: The study found a period effect of declining PPY over the observation period. More recent cohorts of dentists provide lower numbers of PPY than earlier cohorts at similar ages...

Does PubMed Central—a government-run digital archive of biomedical articles—compete with scientific society journals? A longitudinal, retrospective cohort analysis of 13,223 articles (5999 treatment, 7224 control) published in 14 society-run biomedical research journals in nutrition, experimental biology, physiology, and radiology between February 2008 and January 2011 reveals a 21.4% reduction in full-text hypertext markup language (HTML) article downloads and a 13.8% reduction in portable document format (PDF) article downloads from the journals' websites when U.S. National Institutes of Health-sponsored articles (treatment) become freely available from the PubMed Central repository. In addition, the effect of PubMed Central on reducing PDF article downloads is increasing over time, growing at a rate of 1.6% per year. There was no longitudinal effect for full-text HTML downloads. While PubMed Central may be providing complementary access to readers traditionally underserved by scientific journals, the loss of article readership from the journal website may weaken the ability of the journal to build communities of interest around research papers, impede the communication of news and events to scientific society members and journal readers...

Due to a problem of identification, how to estimate the distinct effects of age, time period and cohort has been a controversial issue in the analysis of trends in health outcomes in epidemiology. In this study, we propose a novel approach, partial least squares (PLS) analysis, to separate the effects of age, period, and cohort. Our example for illustration is taken from the Glasgow Alumni cohort. A total of 15,322 students (11,755 men and 3,567 women) received medical screening at the Glasgow University between 1948 and 1968. The aim is to investigate the secular trends in blood pressure over 1925 and 1950 while taking into account the year of examination and age at examination. We excluded students born before 1925 or aged over 25 years at examination and those with missing values in confounders from the analyses, resulting in 12,546 and 12,516 students for analysis of systolic and diastolic blood pressure, respectively. PLS analysis shows that both systolic and diastolic blood pressure increased with students' age, and students born later had on average lower blood pressure (SBP: −0.17 mmHg/per year [95% confidence intervals: −0.19 to −0.15] for men and −0.25 [−0.28 to −0.22] for women; DBP: −0.14 [−0.15 to −0.13] for men; −0.09 [−0.11 to −0.07] for women). PLS also shows a decreasing trend in blood pressure over the examination period. As identification is not a problem for PLS...

We study asymptotics and convergence rates of multiple estimators in a general linear age-period-cohort model with a singular design matrix. The covariates are fixed effects of rows, columns and diagonals in an a × p table with one response in each cell.

A cohort approach is used to detect changes in ethnic identification between the 1986 and 2001 Australian censuses. The aim is to observe whether particular ethnic groups were more or less likely to state the same ancestry in 2001 as in 1986. Age-sex spec

Background. Whether dental amalgam fillings (containing mercury) are hazardous is a long-standing issue, with few epidemiological investigations. Allegations have particularly involved nervous system disorders, such as multiple sclerosis, Alzheimer's disease, and chronic fatigue syndrome. This retrospective cohort study, the largest of its kind, contained people in the New Zealand Defence Force (NZDF) between 1977 and 1997. The NZDF has its own dental service, providing all personnel with regular and consistent treatment. Comprehensive treatment records are maintained and archived. Methods. Yearly dental treatment histories, including amalgam filling placements, were compiled from individual records. To minimize amalgam exposure misclassification the cohort was restricted to people who, at NZDF entry, were aged <26 years and had all their posterior teeth. The cohort was linked with morbidity records. Data were analysed with a proportional hazards model, using a time-varying exposure unit of 100 amalgam surface-years. Results. The final cohort contained 20 000 people, 84% males. Associations with medical diagnostic categories, particularly disorders of the nervous system and kidney, were examined. Of conditions allegedly associated with amalgam...

Background: There is some community survey evidence for a cohort difference in female sexual orientation. Objective: To determine whether there is a cohort difference in sexual orientation in Australia. Methods: A community survey was carried out with a sample of 7,447 adults from the age groups 20-24, 40-44 and 60-64 years. As part of this survey respondents were asked a question on sexual orientation which was answered privately. Results: A strong age cohort difference was found for women, with younger women more frequently reporting a homosexual or bisexual orientation. By contrast, no age cohort difference was found for men. Conclusion: These findings suggest that a heterosexual orientation may have become less common in younger cohorts of Australian women. This finding is consistent with data from other recent studies.

Objective: To quantify any relationship between emergency department (ED) overcrowding and 10-day patient mortality. Design and setting: Retrospective stratified cohort analysis of three 48-week periods in a tertiary mixed ED in 2002-2004. Mean "occupancy" (a measure of overcrowding based on number of patients receiving treatment) was calculated for 8-hour shifts and for 12-week periods. The shifts of each type in the highest quartile of occupancy were classified as overcrowded. Participants: All presentations of patients (except those arriving by interstate ambulance) during "overcrowded" (OC) shifts and during an equivalent number of "not overcrowded" (NOC) shifts (same shift, weekday and period). Main outcome measure: In-hospital death of a patient recorded within 10 days of the most recent ED presentation. Results: There were 34 377 OC and 32 231 NOC presentations (736 shifts each); the presenting patients were well matched for age and sex. Mean occupancy was 21.6 on OC shifts and 16.4 on NOC shifts. There were 144 deaths in the OC cohort and 101 in the NOC cohort (0.42% and 0.31%, respectively; P = 0.025). The relative risk of death at 10 days was 1.34 (95% CI, 1.04-1.72). Subgroup analysis showed that, in the OC cohort, there were more presentations in more urgent triage categories...

Background: Home gas appliance use has been associated with child respiratory illness but prospective data on the relationship between infant exposure and the development of child allergic disease has not been readily available. Objectives: (a) To determine if home gas appliance use is associated with increased risk of house dust mite (HDM) sensitization. (b) To examine whether any association between current home gas use and airway obstruction is influenced by HDM sensitization. Methods: Design: an 8-year follow-up birth cohort study of children born during 1988 and 1989. Participants: a population-based sample (n=498) of children who participated in the Tasmanian Infant Health Survey (TIHS) and resided in Northern Tasmania in 1997 (84% of eligible children). Main outcome measures: (a) Skin prick test reaction to nine allergens, including Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1). (b) Spirometric lung function indices, including forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Results: The relative risk for home gas appliance use at 1 month of age and HDM sensitization was 1.98 (1.04, 3.79) in a cohort analysis with confounder matching. Current home gas use was also associated with HDM sensitization (ARR 1.73 (1.43...

OBJECTIVE: To assess the age, period and cohort effects on breast cancer (BC) mortality in Mexico. MATERIAL AND METHODS: Age, period and cohort curvature trends for BC mortality were estimated through the Poisson Regression model proposed by Holford. RESULTS: Nationally, BC death rates have leveled off since 1995 in most age groups. BC mortality trends are mainly determined by birth cohort and age effects in Mexico. Women born between 1940 and 1955 show the highest rate of increase in BC mortality. Women born afterwards still show an increasing trend but at a much lower rate. Mammography and adjuvant therapy have had a limited impact on mortality. Potential reasons for observed patterns are discussed. An increase in BC mortality in Mexico is expected in the following decades. CONCLUSIONS: Mammography screening programs and timely access to effective treatment should be a national priority to reverse the expected increasing BC mortality trend.

OBJECTIVE: To assess the age, period and cohort effects on breast cancer (BC) mortality in Mexico. MATERIAL AND METHODS: Age, period and cohort curvature trends for BC mortality were estimated through the Poisson Regression model proposed by Holford. RESULTS: Nationally, BC death rates have leveled off since 1995 in most age groups. BC mortality trends are mainly determined by birth cohort and age effects in Mexico. Women born between 1940 and 1955 show the highest rate of increase in BC mortality. Women born afterwards still show an increasing trend but at a much lower rate. Mammography and adjuvant therapy have had a limited impact on mortality. Potential reasons for observed patterns are discussed. An increase in BC mortality in Mexico is expected in the following decades. CONCLUSIONS: Mammography screening programs and timely access to effective treatment should be a national priority to reverse the expected increasing BC mortality trend.

This study identifies the period and cohort effects on the decreasing mortality trend of cancer of the uterine cervix and of the uterus, part unspecified, in the state of Minas Gerais, Brazil, during the period 1980-2005. 11,243 cases were included. A non-parametric method was used to calculate Z statistics and p-values. The cohorts were assessed one by one and also in blocks of three, so as to allow for a larger number of comparisons to be made. Greater than expected mortality reduction was observed for the cohort blocks of women born in 1913-1920; 1927-1936; 1937-1946; 1949-1956; 1963-1970; and 1969-1976. For the 1901-1908 and 1921-1928 cohort blocks a smaller than expected mortality decrease was found. As for period effect, we found a greater than expected reduction for the 2000-2001 period, in comparison with the previous one. The study suggests the existence of a significant cohort effect on mortality due to cancer of the uterine cervix in the study population, and such results have been placed in their social and political contexts.