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At least 19 recordsLinked to original sources
PubMed1988

On the age-period-cohort analysis of suicide rates.

Cohort analysis has become a popular method of examining national trends in suicide rates. Most of the studies investigating this phenomenon have reported a cohort effect to be present. Using a graphical approach, this paper places cohort analysis within the broader framework of age-period-cohort analysis. It is shown that published reports may have failed to identify cohort effects due to using only portions of the available data. With a simple mathematical model it is demonstrated that what appears to be a cohort effect may be a period effect, and conversely. It is recommended that suicide rates be examined for both period and cohort effects before conclusions are drawn regarding trends, and that the complete data set be used for this purpose.

Adolescent↗
PubMed1985

An alternative approach to statistical age-period-cohort analysis.

Age-period-cohort analysis has generated considerable interest in epidemiology, but the model has fundamental problems which have been discussed by Kupper et al. While one can agree that the age-period-cohort model should be used with caution, it should also be noted that some useful inferences can be made with the model. The problems raised by Kupper et al. are discussed in terms of estimable functions of the parameters, which are not affected by arbitrary constraints on the parameters. The use of these methods are illustrated and specific examples presented where age-period-cohort models can be used effectively.

Aging↗
PubMed1990

[A single year birth cohort analysis of mortality in Japan, 1950 to 1984, statistical method and all cause mortality].

Mortality of single birth year cohort were calculated using the data tape of Information Service on World Health Statistics, WHO, 1950-1984. The data tape gave population and number of deaths for each year of age under 5 years of age and by 5 years of age for ages from 5 to 84 years. Population and number of deaths by age for each year of age in each calendar year were estimated by interpolation. Populations for each year of age were interpolated by B-spline interpolation. Number of deaths for each year of age were calculated by application of "two dimensional semi-Hermite method" after estimation of number of deaths for age 80, 81,......84, using Sprague interpolation factors. Age-specific cohort mortality curves were lower for each successive cohort, demonstrating the so-called "cohort phenomenon", clearly. Ratios of mortalities at the same age, for each successive 5 year interval cohort, which indicate cohort-by-cohort changes of mortalities, were thus less than 1.0 in almost all age groups. In recent years the ratios have gradually been leveling off at 0.8-0.9. Cohorts born in the early Showa Era (around 1930) showed higher ratios than all other cohorts, indicating relatively poor improvement in mortalities compared to the other cohorts. Ratios of cohort mortalities for successive ages within the same cohort, which indicates mortalities increase with advance of age, were greater than 1.0 after adulthood. These particular results showed that the increase in mortality with age accelerated after 30 years of age and that a difference in trend was observed between male and female after age 50. This new method of cohort analysis, single birth year cohort, gives clearer results than those obtained by methods heretofore utilized in cohort studies and is useful for more detailed analysis of cohort mortality.

Adolescent↗
PubMed1987

Birth cohort analysis of suicide mortality in Belgium 1954-1981 by a graphic and a quantitative method.

The effect of birth cohort upon the recent increase in Belgian suicide trends was analyzed by two techniques: a graphic display and an Age-Period-Cohort (APC) modelling procedure. Both suggest an analogous pattern: suicide mortality steadily increased within successive male cohorts born after 1920 and within female cohorts born even before 1900. Between 1970 and 1980, period related factors seem to have operated independently. Every technique of cohort analysis however has important interpretational limitations because of the variable interplay between age period and cohort factors. As a consequence, explanations remain very tentative, Notwithstanding its rather poor etiological power in suicide epidemiology, cohort analysis is very useful in the more accurate description and prediction of suicide trends.

Adolescent↗
PubMed1979

Cohort analysis of lung cancer in the Netherlands.

A cohort analysis of lung cancer mortality in the Netherlands from 1936--1974 is presented. Apart from small corrections, age-specific lung cancer mortality rates can be expressed as the product of a cohort (generation) factor and an age factor. The cohort factors increase until the 1930 birth cohort, after which there is a rapid decline. The age-risk factors increase smoothy with age. Age-specific incidence curves of past and future years will follow the curve of the age-risk factors provided that the cohort-risk factors are unchanging. The method can be applied to other chronic diseases.

Adult↗
PubMed1992

Analysis of mortality data from the former USSR: age-period-cohort analysis.

The objective of this article is to review research on age-period-cohort (APC) analysis of mortality and to trace the effects of contemporary and historical factors on mortality change in the former USSR. Several events in USSR history have exerted a lasting influence on its people. These influences may be captured by an APC model in which the period effects measure the impact of contemporary factors and the cohort effects the past history of individuals which cannot be attributed to age or stage in the life cycle. APC models are extensively applied in the study of mortality. This article presents the statistical theory of the APC models and shows that they belong to the family of generalized linear models. The parameters of the APC model may therefore be estimated by any package of loglinear analysis that allows for hybrid loglinear models.

Adolescent↗
PubMed1992

The effect of X-irradiation on cell cycle progression and chromatid aberrations in stimulated human lymphocytes using cohort analysis studies.

Stage sensitivity for the production of chromatid-type aberrations and mitotic delay has been investigated in a stimulated human lymphocyte population, following an absorbed dose of 1.5 Gy 250 kVp X-rays. BrdU replication banding was used to obtain a fine analysis of the cell cycle and to permit cohort analysis. Fluctuations in yield with sample time were found for all aberration categories, but these could not be related simply to either the developmental stage of the cells at time of exposure, or to the time-to-run to metaphase. In general G2 and late S cells had higher aberration yields than early S and pre S cell populations. Mitotic delay and perturbation at this dose extends to all sub-phases of S and is as great, if not greater, in the earliest S cells as it is in G2.

Cells, Cultured↗
PubMed1977

A cohort analysis of pancreatic cancer, 1939--1969.

Pancreatic cancer mortality in the United States was examined by cohort analysis for the period of 1939 to 1969. Birth cohorts at 5-year intervals were studied. White males and non-whites of both sexes showed a shift of the cohort mortality rate curves by age toward younger groups as birth cohorts went from 1870--1874 to 1900--1904. This shift disappeared in white males and diminished in non-whites of both sexes between the cohorts of 1890--1894 and 1900--1904. The shift in non-whites was larger than in white males so that although non-whites had lower rates than whites in earlier birth cohorts, their rates exceeded those of whites in the most recent cohort. In the search for environmental cause(s) of pancreatic cancer, exposure characteristics should be compatible with these observations.

Adult↗
PubMed1985

Attitudes toward social issues in health care: a cohort analysis.

Attitudinal change toward psychosocial issues in health care was tested through a cohort analysis of 190 nursing students at four successive undergraduate levels. The topics examined were: consistency and variability of attitudes toward social issues in health care and relationship between scale performance and age. Attitudinal change among nursing students at four successive undergraduate levels was tested in the present study using a modification of the Attitudes Towards Social Issues in Medicine (ATSIM) Inventory, an instrument composed of seven subscales dealing with various aspects of health care. Techniques used included analysis of variance and Levene's test of the equality of variances. The findings confirmed a process of professional socialization in nursing education with respect to the attitudes of nursing students toward health care issues.

Attitude of Health Personnel↗
PubMed1988

A multistage approach to the cohort analysis of lifetime lung cancer risk among steelworkers exposed to coke oven emissions.

A cohort analysis was performed to predict the lifetime lung cancer risk to a US or Canadian nonwhite male steelworker exposed to coke oven emissions. The procedure employed required that the lung cancer mortality (used for risk assessment) be estimated by addition of the excess to the background rates. The age-specific excess rates were obtained following selection of the proper excess risk function as implied by the multistage theory of carcinogenesis. A quantitative approach based on model fitting was used for selection of the excess risk function. The results show no evidence that coke oven emissions have a late stage carcinogenic effect. The indication that the agent acts as an initiator is moderate to weak. The number of carcinogenic stages involved was estimated to be four. Based on the assumption that exposure was set at a high concentration for 40 years with a starting age of 20 years, it was estimated that the lifetime risk through age 85+ years for a hypothetical US or Canadian nonwhite male oven worker could be as high as 0.40. This represents a 15-fold increase of the baseline risk.

Adult↗
PubMedDate not supplied

[Age-period-cohort analysis of mortality caused by ischemic cardiopathy in Spain 1965-1985].

With the objective of studying the temporal evolution of ischaemic cardiopathy (IC), or coronary heart disease mortality, in Spain, we carried out a cohort analysis with conventional graphic techniques and modern statistical methods. This permits better understanding and quantification of the age-period-cohort effects and identification of the potential factors operating upon them. To this end, loglineal (Poisson regression) models were constructed of the IC mortality rates for both sexes, using the GLIM package, in which the regression coefficients are the natural Relative Risk (RR) logarithms of the various age groups (35-74 years), period of death (1970-1985) and birth cohort (1985-1960) with respect to the reference group mortality, controlled by the effect of other groups. In respect of the results, the maximum RR value corresponds to decrease year 1975, and falls progressively to 1985, though at all times remaining above the 1970 value. The effect of 1985, though less than 1980, does not present significant differences from the latter. Nevertheless, no clear cohort effect was found. As a probable explanation for the pattern observed, this would suggest recent changes in life style and in medical attention. There is a discussion of the consistency of the models selected with the graphical results and with present knowledge of the natural history of IC and with the evolution of its determining factors, together with validation of the models. In summary, the IC mortality patterns observed show an increase up to the mid-seventies, and stabilization from that date onwards, in all age and sex groups, which is consistent with an age-period effect.

Adult↗
PubMed1985

Birth-cohort analysis of peptic ulcer mortality in Europe.

The age- and sex-specific death rates of gastric and duodenal ulcer are followed in eight European countries over a period ranging from 30 to 60 yr. A cohort analysis demonstrates that the temporal changes of peptic ulcer mortality in the European countries seem to occur in a fashion characteristic of those due to changes in birth-cohort risks. Generations born at the end of the 19th century manifested a high risk of dying from gastric and duodenal ulcer. The birth-cohorts with a high risk for duodenal ulcer lagged 10-30 yr behind those with a high risk for gastric ulcer. Male and female cohorts with the highest risk were born at the same time. The birth-cohort phenomenon is most obvious in male death rates of gastric and duodenal ulcer. A birth-cohort phenomenon would imply that important determinants for the development of gastric and duodenal ulcer occur early in the life of a cohort and that it is these early determinants that are changing with time. The determinants could be environmental factors which interact with the pathophysiology of peptic ulcer from the outside.

Adult↗
PubMed1989

Birth cohort analysis of prevalence of cigarette smoking among Hispanics in the United States.

To investigate historical trends of cigarette smoking among Mexican-Americans, Cuban-Americans, and Puerto Rican-Americans, we conducted a birth cohort analysis of smoking prevalence by using smoking histories of 8286 adults and adolescents from the 1982-1983 Hispanic Health and Nutrition Examination Survey. We constructed smoking prevalence curves for men and women among successive ten-year birth cohorts. Birth cohort-specific prevalence rates were higher for men than for women. Rates, however, decreased among successive cohorts of men. Conversely, rates increased among successive cohorts of Cuban-American and Puerto Rican-American women. For example, peak rates among the 1911 through 1920 cohorts were 26% (Cuban-American women) and 25% (Puerto Rican-American women) compared with peak rates of 43% and 52%, respectively, among comparable groups from 1951 through 1960. These results demonstrate that despite a reduction of cigarette smoking among successive cohorts of Hispanic men, Hispanic women have made little progress or have actually increased their cigarette smoking.

Adolescent↗
PubMed1985

Mortality from prostate cancer in Italy: 1950-1979. Cross-sectional rates and cohort analysis.

This paper studies prostate cancer mortality in Italy from 1950-1979 to evaluate its importance in relation to total cancers, examine the time trend for forecasting future mortality trends, and makes an attempt to interpretate mortality by analyzing demographic and risk factors. In the Authors' opinion findings from cross-sectional rates, cohort analysis and Devesa-Schneiderman method, indicate that in Italy even if the age-adjusted mortality rate has nearly doubled over the period, as in many other countries, mortality can be expected to remain constant or decrease in the future, since the data to hand show a decreasing trend in some age cohorts.

Age Factors↗
PubMed1987

Age-period-cohort analysis of secular trends in onset of major depression: findings in siblings of patients with major affective disorder.

Analyses of data from the NIMH-CRB Collaborative Depression Study on age at onset of Major Depressive Disorder (MDD) in 1144 directly interviewed siblings of patients with major affective disorder show a strong secular trend toward increased lifetime risk and earlier onset in successive cohorts of birth since 1930. The proportionate increases in the instantaneous probabilities (hazard) of onset of MDD for each one year difference in year of birth were 5% for brothers and 7% for sisters. Age-period-cohort analysis suggests a powerful period effect may be responsible for this secular trend in rates of MDD, with rates of onset for siblings between 15 and 50 years of age doubling between the 1960s and 1970s. Possible artifacts are investigated.

Adolescent↗
PubMed1985

Statistical age-period-cohort analysis: a review and critique.

Descriptive and statistical age-period-cohort (APC) analysis methods have received considerable attention in the literature. The statistical modeling of APC data often involves the popular multiple classification model, a model containing the effects of age groups (rows), periods of observation (columns), and birth cohorts (diagonals of the age-by-period table). The identifiability problem inherent to this model is discussed, and its adverse effects on the results of APC modeling exercises are illustrated numerically. Potential problems attendant with the use of two-factor models are described, and other possible modeling approaches currently in use are discussed. Interpretational limitations due to certain innate characteristics of typical APC data sets are also detailed. Given all the documented potential sources for error, the current state-of-the-art regarding the statistical modeling of APC data should be considered to be at an early stage of development.

Adult↗
PubMed1986

Cohort analysis of Ontario suicide rates, 1877-1976.

Birth cohort studies of suicide rates in Alberta, the United States and Australia indicate that within each generation, suicide rates increase with age. Such studies argue that cohort-specific suicidal risk, together with present high suicide rates among young people predict even higher rates as these generations grow older. Ontario data from a 100-year period demonstrate that within birth cohorts suicide rates consistently increase with age, peak between ages 50 and 70, then decline. Gradual increases in mean suicide rates result in every birth cohort having higher suicide rates than the preceding cohort at almost every age level. These trends combine to produce a regular birth cohort effect and a steady shift in cross-sectional data to higher rates of suicide among younger age groups. Abrupt increases in suicide rates occurring during the Great Depression had only transient effects on birth cohort and cross-sectional curves. Results provide weak support for the hypothesis of cohort-specific suicidal risk and clarify the factors which produce birth cohort effects.

Adolescent↗