Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cohort Analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1987

Suicide in Texas: a cohort analysis of trends in suicide rates, 1945-1980.

Recent clusters of teenage suicides in Texas suburban communities have focused national attention on the rise in teenage suicidal behavior. This study sought to clarify the teenage suicide phenomenon by using a cohort method of data analysis. Beginning with suicide rates for white males aged 15-19 in 1945, suicide rates were calculated and plotted for each 5-year age cohort entering the late teenage years, when suicide risk factors dramatically increase. Our analysis of these cohort patterns confirmed the ever-rising risk factor associated with the ages of 15-19. This trend is consistent with many studies suggesting that teenage suicide is a function of socioeconomic and psychological factors operating across community and national boundaries. In addition, our study revealed that as white males 15-19 years of age in 1945 aged, their suicide rates also increased, confirming earlier findings that the suicide risk factor increases with age. In fact, Texas data for 1980 revealed that older persons, not teenagers, had the highest suicide rates-a finding that confirms other studies' results. Finally, Texas cohort patterns for suicide revealed the recent curvilinearity tendencies of older adult male suicide rates. By 1980 Texas data revealed a bimodal distribution of high suicide risk, with white males in their late 20s and ages 55 and over having the highest rates.

Adolescent↗
PubMed1989

A birth cohort analysis of dental contact among elderly Americans.

We applied standard cohort and multiple regression techniques to data on the dental utilization rates of 129,191 elderly individuals taken from the 1972, 1973, 1976, 1977, 1980, and 1981 Health Interview Surveys. The results indicate that the marked variation in dental contact rates is a reflection of cohort succession, and not a function of aging per se. Older cohorts having lower dental contact rates are being replaced by younger cohorts having higher dental contact rates. The dental contact rates of the individual birth cohorts themselves are quite stable over time. The results also indicate that economic barriers (especially liquid assets) have become more important than ever before, especially for the oldest-old. These findings have important implications for public policy about the oral health and health care of elderly Americans.

Age Factors↗
PubMedDate not supplied

Education and timing of parenthood among Canadian women: a cohort analysis.

This research examines factors associated with the timing of first birth in Canada, focusing primarily on the role of women's educational attainment. Proportional hazards modelling techniques are applied to data from the 1984 Canadian Fertility Survey (CFS) in order to determine how educational attainment, estimated as close as possible to the date of first birth, influences the timing of first birth and whether the importance of this variable varies according to age cohorts. The results suggest that among a number of variables useful for distinguishing different levels of risk, educational attainment proves to be the most important predictor in the model. Education exerts a substantial positive influence on birth timing for women of all age groups. As expected, moreover, significant cohort differences are also evident, with the greatest to the smallest impact on the risk from the youngest to the oldest cohorts. These clear-cut cohort differences indicate a fundamental change in the effects of education over time, a trend most likely resulting from substantial changes in both the content and social significance of formal schooling during the past few decades.

Adolescent↗
PubMed2001

Rates of preterm delivery among Black women and White women in the United States over two decades: an age-period-cohort analysis.

The authors assessed the influence of age, period, and cohort effects on rates of preterm delivery in the United States. Rates of preterm delivery for singleton births (<37 weeks) in seven age groups (15-19, 20-24,., 45-49 years), five periods (1975, 1980, 1985, 1990, 1995), and 11 maternal birth cohorts (1926-1930, 1931-1935,., 1976-1980) were examined. Over the 20-year study interval, preterm delivery increased by 3.6% among Blacks (from 15.5% in 1975 to 16.0% in 1995) and by 22.3% among Whites (from 6.9% to 8.4%). Among Black primigravid women, rates of preterm delivery increased from 1975 to 1990 and began to decline thereafter; among Whites, the rates increased between 1975 and 1995. In Blacks, women aged 25-29 years had the lowest rates for the first and second births, and women aged 30-34 years had the lowest rate for subsequent births. In Whites, the age groups with the lowest preterm delivery rates were 20-24 years for first births and 25-29 years for subsequent births. Cohort-specific rates of preterm delivery remained fairly constant across age strata and periods for Whites, but a small trend was apparent for Blacks aged 30-44 years. The consistency of the observed age effects across periods and cohorts suggests that the age effect is partly due to biologic factors. The presence of period effects might be linked to the increased survival of premature infants or to increased viability among births occurring at lower lengths of gestation.

Adolescent↗
PubMed1998

Age-period-cohort analysis of chronic disease rates. I: Modelling approach.

Age-Period-cohort models are widely used by epidemiologists to analyse trends in disease incidence and mortality. The interpretation of such models is fraught with difficulty in view of the exact linear dependency between the three variables. It is the purpose of this paper to review, compare and contrast some of the more common approaches to this problem based on Poisson regression and a linear model for the log rates. Also the results of using the different approaches on a single series of data on breast cancer incidence among females in Scotland from 1960-1989 are presented for comparison. Recommendations as to the merits and drawbacks of the approaches are also given in the conclusions. Models which are based upon the estimable contrasts such as local curvatures and deviations from linearity are most suitable.

Adolescent↗
PubMed1990

Cohort analysis of retirement preparation, 1974-1981.

Extending Easterlin's (1987) thesis regarding cohort size and personal welfare, this study was designed to examine cohort differences and changes in preparation for retirement. The data on which the study is based came from two cross-sectional surveys commissioned by the National Council on the Aging and conducted in 1974 and 1981. Major research questions included: (a) Which cohorts are most active in taking steps to prepare for retirement? and (b) Did Americans increase their retirement preparation activities during the time period studied? Results indicate that retirement preparation is influenced by cohort effects, especially among the more recent cohorts, and that earlier cohorts generally prepare more. Most respondents, especially the earlier cohorts, experienced a decrease in retirement preparation between 1974 and 1981 (i.e., a period effect). Analysis of the separate indicators of a retirement preparation index show that most activities, for instance, savings, decreased during this time while others either increased (will preparation) or remained stable (home ownership). The findings suggest that retirement preparation is influenced by economic climate and provide partial support for this application of Easterlin's thesis. Retirement preparation is also strongly related to education and race.

Adolescent↗
PubMed1997

Trends of liver cirrhosis mortality in Europe, 1970-1989: age-period-cohort analysis and changing alcohol consumption.

BACKGROUND: Since the mid 1970s, a striking reduction in alcohol-related problems has been observed in many Western countries. Liver cirrhosis mortality is considered to be a major indicator of alcohol-related problems in the general population. The aim of the present study is to describe liver cirrhosis mortality trends in European countries between 1970 and 1989. METHODS: This is a descriptive study on liver cirrhosis mortality in 25 European countries, and in four grouped European regions. A Poisson log-linear age-period-cohort model is used to clarify whether the recent trend in mortality represents a short-term fluctuation or an emerging long-term trend. In addition, a descriptive comparison between trends in per capital alcohol consumption and liver cirrhosis mortality is conducted. RESULTS: In the whole European population and in that of Western and Southern Europe increasing period effects were observed until the second half of the 1970s followed by a decline in the next periods. In Eastern Europe the decline in period effects started in the first half of the 1980s, whereas in Northern Europe an increasing period effect was observed until the second half of the 1970s, followed by a stabilization. Similar trends were observed for per capita alcohol consumption. The age effect analysis showed a continuously rising effect in Eastern Europe, whereas an attenuation of the effect at around age 65 years was observed in Western Europe. Intermediate patterns were observed in Southern and Northern Europe. The birth cohort effect suggested that in the Western and Southern populations mortality could continue to decrease over the next decade, while in Eastern and Northern mortality is still rising and this will probably continue for the next decade. CONCLUSIONS: The age-period-cohort analysis allows targeting of health care and prevention programmes based on future trends. Aetiological and prognostic factors act differently in Europe. A better understanding of the trends would require more detailed information on alcoholism treatment rates, alcohol habits, viral hepatitic infections and other factors involved in the aetiopathogenesis of the disease.

Adult↗
PubMed1987

Retrospective cohort analysis of class A mishaps in aviators evaluated at USAFSAM: 1957-1984.

A retrospective analysis of Class A mishaps in all United States Air Force (USAF), Air National Guard (ANG), and Air Force Reserve (AFR) pilots (n = 5088) evaluated at the USAF School of Aerospace Medicine (USAFSAM) from 1957-84 was conducted to test whether the cohort career mishap experience differed significantly from the general USAF, AFR, and ANG pilot population. The analysis involved merging the USAFSAM Cover Sheet computer file with the Aircraft Accident Data System and Flight Record Data System maintained at the Air Force Inspection and Safety Center, Norton AFB, CA. A life table analysis compared observed cohort mishap accumulation over career flight hours with theoretical curves derived from USAF wide aircraft year-specific Class A mishap rates. The cohort experienced significantly fewer (p less than 0.005) mishaps over career flight hours in all major aircraft categories except trainers, in which the cohort experienced significantly more mishaps (p = 0.013). Areas for further analyses based on these preliminary findings are discussed.

Accidents, Aviation↗
PubMed1982

A cohort analysis of U.S. stomach cancer mortality 1950-1977.

Models of human carcinogenesis, such as the multi-stage model of Armitage and Doll, are designed to explain the age increase in the incidence of cancers in individuals. As a consequence, analyses of population level age-specific death rates via such models are appropriately applied to cohort data where such data are available. In this study a multi-stage model is applied to cohort data for stomach cancer death rates in the U.S. population for nine distinct cohorts observed over a recent 28-year period (1950-1977). The multi-stage model parameters obtained from the analysis of the cohort data show significant differences from the parameters obtained from analyses of cross-sectional mortality data under the assumption of no cohort differences in age-specific stomach cancer death rates.

Adult↗
PubMed1982

Cohort analysis of recent trends in labor force participation.

The age-period-cohort accounting framework is used to describe labor force participation patterns for the sex-color groups over the interval 1969-1979, using data from the March Current Population Survey. A model with a special type of age-period interaction, in addition to main effects of the three indexing variables, is presented as a means of capturing the transitory period "shocks" which differentially influence participation odds for young and old age groups. Findings show that younger cohorts of nonblack men, nonblack women, and black women have greater "intrinsic" tendencies to participate than older cohorts, while younger cohorts of black men have lesser "intrinsic" tendencies to participate than older cohorts. The results are used to decompose across-time change into a part due to cohort effects and a part due to period effects.

Adolescent↗
PubMed1989

Suicide in England and Wales 1946-1985: an age-period-cohort analysis.

Four decades of suicide mortality data for England and Wales were analysed within an age-period-cohort framework. Marked differences in results were found by sex. The analysis of the male data showed that the risk of suicide increased with age until men were in their mid-fifties (after allowing for period and cohort effects), and that suicide risk declined for males born from 1876 to 1915, but had increased over 4-fold for certain later-born cohorts. Female suicide risk was found to decline with later nativity (after adjusting for age and period effects). The identification of period effects in terms of known changes in the carbon monoxide (CO) content of domestic gas successfully accounted for temporal variation in male suicide risk, but fitted less well to the data for females.

Adult↗
PubMed1991

Cancer of the lung and urinary bladder in Denmark, 1943-87: a cohort analysis.

National data from 1943 to 1987 on the two most frequent tobacco-related cancers in Denmark, lung and bladder cancer, were analyzed with multiplicative Poisson models. The temporal trends in the cohort-specific risks for both sites and sexes were similar: the risks increased in the beginning of the period covered by the analysis, but then levelled off; and there was no increase among cohorts born after circa 1930. Women experienced a smaller increase during the period covered by the analysis in the cohort-specific risk for bladder cancer than men (3.7 cf 6.1 times), whereas the overall increase in lung-cancer cohort-specific risk was the same for both sexes. The difference could not be explained by trends in tobacco consumption, types of tobacco consumed, or occupational exposures. On the basis of these findings, it is suggested that women may be less susceptible than men to developing bladder cancer from tobacco smoking.

Adult↗
PubMed1993

A multivariate example of case-cohort analysis: neonatal mortality in Switzerland, 1979-81.

A study of all births in Switzerland during the years 1979-81 is used to illustrate the advantages of the case-cohort design for this epidemiologic analysis of neonatal mortality. The example shows that familiar associations between infant mortality and explanatory variables such as sex and weight at birth can be precisely estimated using only a sample from the full cohort.

Birth Rate↗
PubMedDate not supplied

Age-period-cohort analysis of breast cancer mortality.

The objective of this study is to develop a hypothesis about the carcinogenesis of breast cancer from a descriptive analysis. This study is an application of the age-period-cohort model (APC model) on the mortality rate of breast cancer in Taiwan over the period from 1964 to 1991. Age-specific and age-adjusted mortality rates are described and then age, period, and cohort effects are separately analysed. (Female) breast cancer mortality data in Taiwan from 1964 to 1991 were abstracted from the annual reports of the Taiwan Provincial Department of Health. The population data in Taiwan from 1964 to 1991 were abstracted from the demographic data in Taiwan compiled by the Ministry of Interior, R.O.C. The results show that both age-adjusted and age-specific mortality rates of breast cancer are increasing over the study period and with birth cohorts. The bimodal pattern becomes more apparent in later periods. The Clemmensen's hook is five years later both in the descriptive study and the APC analysis. The findings suggest a possible role of later life overnutrition as the major period effed (promoter) and a change in reproductive behavior as the cohort effect (initiator). The application of the APC model also denotes the possible role of later life overnutrition and a change in reproductive behavior after the birth cohort of 1929. These findings may help us develop hypotheses of carcinogenesis of breast cancer.

Adult↗
PubMed1985

Multivariate cohort analysis.

Modern methods of categorical and survival data analysis are usefully applied to the multivariate analysis of follow-up data that arise in epidemiologic cohort studies. They provide a formal basis for extending analyses based on the standardized mortality ratio into the multivariate domain so as to permit simultaneous consideration of such risk factors as age, duration, and intensity of exposure; age and calendar year of follow-up; and personal characteristics. Analogous methods are available that control for demographic variables internally, without reference to vital statistics or other standard rates. Various model structures allow for the effects of different variables to combine in an additive, multiplicative, or mixed (additive relative risks) fashion. Illustrative analyses are provided of the relationship between respiratory cancer mortality and arsenic exposure in a cohort of Montana smelter workers.

Arsenic↗