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At least 199 records · Page 11Linked to original sources
PubMed1994

Harsh social conditions and perinatal survival: an age-period-cohort analysis of the World War II occupation of Norway.

OBJECTIVES: The hypothesis was tested that unfavorable social conditions are associated with poor perinatal survival through direct effects on pregnancy or, more indirectly, through effects on mothers born under such conditions. The occupation of Norway by Nazi Germany was used as a period of social hardship. METHODS: Data from Norwegian vital statistics and the Medical Birth Registry were used to describe perinatal mortality during World War II and also a generation later, among babies born to mothers who had themselves been born during the war. Logistic regression was used to identify a possible cohort effect among mothers born in 1940 through 1944 compared with mothers born before or after that period. RESULTS: Harsh conditions in Norway during the occupation increased childhood mortality. However, perinatal mortality declined during that period. Likewise, no adverse effect was seen on the survival of babies born to mothers who had themselves been born during the war (odds ratio = 1.00; 95% confidence interval = 0.96, 1.04). CONCLUSIONS: We find no evidence that wartime conditions in Norway impaired perinatal survival, either directly or through an effect on women born during the war. These data underscore how little is known about the ways that social conditions influence perinatal mortality.

Adolescent↗
PubMed2004

Recent increase in cancer survival according to age: higher survival in all age groups, but widening age gradient.

A major increase in long-term survival of cancer patients in the 1990s has recently been demonstrated. It is unclear, however, to what extent this increase has been shared by cancer patients at various ages. Using the 1973-2000 data base of the Surveillance, Epidemiology, and End Results programme, recent increase in 10-year relative survival of cancer patients in the US was assessed for 4 major age groups and 15 major cancer sites by comparing results of a period analysis for the 1996-2000 period with results of a cohort analysis for patients diagnosed in 1986-1990. Period estimates of 10-year relative survival for all forms of cancer combined in 1996-2000 were 66.1%, 58.8%, 56.3% and 47.1% for age groups 15-54, 55-64, 65-74 and > or = 75 years, respectively. They were 7.4%, 10.4%, 7.8% and 3.0% units higher than the respective 1986-1990 cohort estimates for these age groups. The increase in 10-year relative survival strongly varied by cancer site, but it was generally less pronounced in older than in younger patients. We conclude that long-term survival expectations of cancer patients have increased in all age groups in the 1990s. However, for most common forms of cancer, the age gradient in survival has either persisted or widened.

Adolescent↗
PubMed2005

Age-period-cohort analysis of suicide rates in Rio de Janeiro, Brazil, 1979-1998.

BACKGROUND: Recent studies in Brazil have demonstrated that suicide rates have been rising over the last years. The objective of this study was to investigate trends in suicide from 1979 to 1998 in Rio de Janeiro State, with emphasis on age, period, and cohort effects. METHOD: Age-specific suicide rates from 1979 to 1998 were estimated for males and females based on mortality data obtained from the Brazilian Mortality Information System, and population counts from the 1980, 1991 and 2000 censuses. Poisson regression and graphical methods were used to evaluate age, period and cohort effects. RESULTS: Suicide rates increased steadily with age, particularly among males. In both males and females, age-adjusted suicide rates decreased until 1992. In 1993, rates started to rise. Cohort effects showed that younger generations had significantly lower rates of suicide than older ones. CONCLUSION: The recent rise in suicide rates might be a result of the increasing levels of firearm availability, drug use, and unemployment. Follow-up over longer periods and powerful epidemiological studies are needed to sustain the implication of socio-economic changes in the observed features.

Adolescent↗
PubMed2003

Increasing incidence of non-Hodgkin's lymphoma in Canada, 1970-1996: age-period-cohort analysis.

Previous studies have shown that the incidence of non-Hodgkin's lymphoma (NHL) has increased in many parts of the world in recent decades. Using data obtained from the Canadian Cancer Registry, the present study examined time trends in NHL incidence in Canada between 1970 and 1996 and the effects of age, period of diagnosis and birth cohort on incidence patterns for each sex separately. Results showed that overall age-adjusted incidence rates increased substantially, from 7.3 and 5.2 per 100,000 in 1970-1971 to 14.0 and 10.0 per 100,000 in 1995-1996 in males and females, respectively. Diffuse lymphoma was the major histological subtype, accounting for approximately 76% of NHL cases over the 27-year period. The data suggest that period effects have played a major role, although birth cohort effects may also have been involved. Sex-specific patterns of the incidence were similar over the time period of diagnosis but were distinct among recent birth cohorts. In conclusion, there is in fact a marked increase in NHL in Canada which cannot be explained in terms of improvements in diagnosis, changes in NHL classification and the increase in AIDS-associated NHL alone. The birth cohort effect in NHL suggests that changes in risk factors may have contributed to the observed increase.

Adolescent↗
PubMed1999

Rotaviruses detected by reverse transcription polymerase chain reaction in acute gastroenteritis during a trial of rhesus-human reassortant rotavirus tetravalent vaccine: implications for vaccine efficacy analysis.

BACKGROUND: Rotaviruses are routinely diagnosed by detection of rotavirus antigen in stools using an enzyme immunoassay (EIA). A sensitive method, like reverse transcription polymerase chain reaction (RT-PCR), may reveal more rotaviruses, but the clinical significance of such findings is not well established. OBJECTIVES: To study whether RT-PCR can detect more episodes of rotavirus-associated gastroenteritis than EIA and to determine how rotavirus RT-PCR findings might change efficacy analysis of a rotavirus vaccine trial, in which the outcome measure was rotavirus gastroenteritis diagnosis with EIA. STUDY DESIGN: We applied RT-PCR for detection of rotaviruses in gastroenteritis episodes encountered in an efficacy trial of rhesus-human reassortant rotavirus tetravalent (RRV-TV) vaccine, in a total of 2398 infants. During a follow-up, covering two rotavirus epidemic seasons, 256 cases of rotavirus associated gastroenteritis were detected by EIA; 226 were in the primary efficacy analysis period that included children who had received three doses of vaccine or placebo. RESULTS: With RT-PCR, 84 (33%) more cases of rotavirus gastroenteritis were diagnosed than with EIA, 65 of these were in the primary efficacy analysis period. Clinically, cases of rotavirus gastroenteritis diagnosed by RT-PCR were much milder (median severity score 6 on a 20-point scale) than those diagnosed by EIA (median score 11), P < 0.0001. RT-PCR revealed proportionally more G2 and G4 rotaviruses than EIA. G1 rotaviruses detected by RT-PCR were almost equally divided between RRV-TV (25) vaccine and placebo (28) groups, whereas an apparent vaccine protective effect was seen in the distribution of G2 (one in the RRV-TV and eight in the placebo group) and G4 rotaviruses (six in the RRV-TV and 14 in the placebo group). CONCLUSION: RT-PCR is a useful tool in the diagnosis of rotavirus gastroenteritis, particularly for cases associated with other than the epidemiologically dominant G-type. Application of RT-PCR contributes to the overall appraisal of performance of rotavirus vaccine.

Acute Disease↗
PubMed2006

Age-period-cohort analysis of female breast cancer mortality in Korea.

BACKGROUND: Although breast cancer in women remains relatively rare in Korea, its incidence and mortality figures are increasing, consistent with the increasing risk observed in successive generations of Korean women. The aim of the current study was to examine time trends of breast-cancer mortality during the period 1984-2003 in Korea, assessing the importance of the effects of age, period and birth cohort as risk factors. METHODS: Data on the annual number of deaths due to female breast cancer and on female population statistics from 1984 to 2003 were obtained from the Korean National Statistical Office. A log-linear Poisson age-period-cohort model was used to estimate age, period and cohort effects. RESULTS: The trend of breast cancer mortality was explained by an age-cohort model based on goodness of fit, even though the significance of the cohort effect was marginal (p=0.08) after adjusting for age. The risk of breast cancer death was found to increase with age after adjusting for the cohort effect, and it was different from the cross-sectional age curve. Also, breast cancer mortality increased along with the birth cohort. CONCLUSIONS: Even though the cohort effect was found to have a marginally significant effect on breast cancer mortality, it is expected to be more significant in the future given the recent on-going changes in diet and reproductive behavior shown by Korean women.

Adult↗
PubMed2004

Small-for-gestational-age births in the United States: an age-period-cohort analysis.

BACKGROUND: During the last 2 decades, the rate of low birthweight has increased, as has the rate of preterm delivery, among both whites and blacks. Examination of causes for these secular trends has focused largely on changes in the distributions of maternal age and, less commonly, on birth cohort. Little is known as to how age, period, and birth cohort interact on trends in small births at term. METHODS: The U.S. natality files were used to assess trends in term (>/=37 weeks gestation) small-for-gestational age (SGA) births for 7 5-year maternal age groups (15-19 through 45-49 years), 6 delivery periods (1975, 1980, 1985, 1990, 1995, and 2000), and 12 5-year maternal birth cohorts (1926-1930 through 1981-1985). SGA births were defined as sex-specific birthweight below the 10th percentile for gestational age based on 1995 livebirths in the United States. Logistic regression models were fit to determine the independent effects of age, delivery period, and birth cohort on term SGA trends, separately for blacks and whites. RESULTS: Between 1975 and 2000, term SGA births declined by 23% (from 21% to 16%) among blacks and by 27% (from 12% to 9%) among whites. Term SGA births declined with increasing age up to 30-34 years, but increased among older women. Within strata of maternal age, the risk also declined with later maternal birth cohorts, among both blacks and whites. The strongest influence on SGA trends was from maternal age, followed by maternal birth cohort, and lastly by delivery period. In general, for any combination of age, period, and birth cohort, blacks showed 1.5- to 2-fold higher rates of term SGA than whites. CONCLUSIONS: The persistence of strong maternal age effects on risk of term SGA births suggests that the effect of age is at least partly the result of biologic factors. Term SGA trends were generally consistent for blacks and whites, although the magnitude of difference in the risks for combinations of age, period, or mother's birth cohort was higher among blacks than whites.

Adolescent↗
PubMed2001

[Ultrastructural changes in organelles of the dog cerebral cortex astrocytes in post-ischemic period (morphometric analysis)].

Morphometric analysis of volume density of mitochondria, rough endoplasmic reticulum (RER), Golgi complex, vacuoles, lysosomes, fibrils, superficial density of mitochondria and RER, postischemic mitochondria/RER superficial and volume ratio and astrocyte ultrastructure was carried out experimentally in dogs. The findings obtained indicate that in early postischemic period (5-10 min-3-7 d) changes in astrocyte were reactive, although since the second wk of postischemic period metabolic processes in astrocytes were disturbed, which were manifested through structural changes maximally pronounced on d 14-21 of reparative period. At late reparative period (first-third month) astrocyte structure was normalised to significant extent.

Animals↗
PubMed2001

Recent trends and future projections of lymphoid neoplasms--a Bayesian age-period-cohort analysis.

OBJECTIVES: A steady increase in incidence of lymphoid neoplasms has been reported, especially for non-Hodgkin's lymphoma (NHL). Using high-quality incidence data from 1973-1992 in nine population-based cancer registries (Alberta, Bombay, Denmark, Israel, New Zealand, Osaka, Oxford, Slovenia, Utah), we have examined past increases in specific lymphoid neoplasms. Further, by using a Bayesian age-period-cohort approach, we have calculated 5-, 10- and 15-year projections for each group of lymphoid neoplasms. RESULTS: NHL incidence increased in all centers by an average of 77% in men and 66% in women between 1973 and 1992. Fifteen-year projections of these rates to 2003-2007 indicate that they will increase by an average of 55% among men and 79% among women. High projected incidence rates above 15/100,000 in men and 10/100,000 in women are expected in Alberta, Denmark, Israel, New Zealand, Oxford, and Utah by 2003-2007. The one notable exception was among men from Osaka, where no increase was projected. Modest increases in leukemia and multiple myeloma rates were observed in most of the nine registries with further projected increases by 2007. Projected incidence rates of Hodgkin's disease indicated little change. CONCLUSION: Increases in NHL rates are occurring worldwide and provide no evidence of peaking. A key assumption in the projected rates is that the effect of environmental agents determining the trends during 1973-1992 will remain stable during the subsequent projection period.

Age Factors↗
PubMed1994

The monitoring of orthodontic tooth movement over a 2-year period by analysis of gingival crevicular fluid.

Gingival crevicular fluid (GCF) was collected from around canine teeth before orthodontic treatment, during retraction, and in retention. The aim was to investigate the changes in the flow of GCF and its glycosaminoglycan (GAG) components at these three stages of orthodontic treatment, and relate them to tooth movement, gingival inflammation, and other clinical parameters recorded at the time of GCF sampling. GAG in GCF samples, collected for a 15-minute period into microcapillary tubes, were separated and identified electrophoretically, stained with Alcian blue and quantitated using a laser densitometer. The increase in GCF volume during orthodontic tooth movement and the decrease during retention are only partly due to changes in the severity of gingival inflammation. Levels of the GAG component chondroitin sulphate found in GCF samples taken during retention appear to be related to the duration of retention, particularly the length of time that the fixed appliance is passive before debonding. GCF analysis may assist the clinician to conduct this phase of orthodontic retention more reliably.

Adolescent↗
PubMed2005

Americans' attitudes toward welfare state spending for old-age programs: an analysis of period and cohort differences.

Using data from the General Social Survey the current study examines period and cohort differences in attitudes toward welfare state spending for old age programs. Using the Torres-Gil classification system, the study uses cross-sectional data from the 1984-2004 waves of data to identify any differences by period and cohort group membership in whether or not it is the government's responsibility to provide a decent standard of living for older adults, whether or not respondents felt that the current level of spending for Social Security was adequate, and whether or not respondents were willing to make sacrifices such as paying higher taxes to pay for greater retirement benefits. The findings suggest that the generational conflict that many suggested might arise has not come to fruition. Indeed, the youngest cohorts in these analysis were the most likely to support higher taxes to pay for better retirement benefits. Perhaps more interesting were the findings that there were no significant period effects for whether or not the government was responsible for providing a decent standard of living but there were such effects when examining whether or not Social Security funding levels were adequate.

Adult↗
PubMed2002

Trends in colorectal cancer incidence in Norway by gender and anatomic site: an age-period-cohort analysis.

The purpose of this study was to examine the secular trend of colorectal cancer in Norway by gender and subsite. All new cases of cancer in proximal colon, distal colon and rectum diagnosed between 1958 and 1997 in Norway were included in the study, altogether 34 202 and 34 097 cases for men and women, respectively. The incidence data were fitted separately for each gender and subsite to an age-period-cohort model. An increase in incidence of colorectal cancer was seen from 1958 to 1997 for both men and women, although a moderate attenuation of the increase has taken place in the last 15-20 years. This observation is most pronounced for cancer of the distal colon, but is also evident for proximal colonic and rectal cancers. For the distal colon and rectum, the period effect is more important than the cohort effect for both genders, whilst opposite for the proximal colon. The main estimated trend for cohort effects is a steady increase for both men and women, apart from an unexpected drop in incidence among the cohorts born during or shortly after World War II. These findings indicate that different aetiological risk factors may act on cancers of the proximal and distal part of the large bowel and further suggest that exogenous risk factors acting very early in life may play a more important role for colorectal cancer than previously recognized.

Adult↗
PubMed1993

Enhanced period-peak analysis of the electroencephalogram using a fast Sinc function.

EEG computer analysis is still not widely used in the clinic, and the need for advanced signal processing techniques is still warranted. The fast Fourier transform (FFT) is the method most frequently used for power spectrum estimation of the EEG. In an effort to reduce memory space and processing time required by the fast Fourier transform (FFT), a new method, the enhanced period-peak detection (EPPD), is investigated. The method is based on a combination of the Fourier transform (FT) and period-peak detection. The signal is considered as a train of truncated sinusoidal functions. Each truncated sinusoidal function is limited by two successive local extrema (a peak and a valley). The Fourier transform of the truncated sinusoidal function is the well known Sinc function. The summation of these Sinc functions yields an approximate frequency spectrum of the signal. The speed and performance of the FFT rely upon the number of data collected and the sampling frequency. On the other hand, the enhanced period-peak detection (EPPD) method does not require that the entire EEG data be stored. Only the extrema of the signal and time between the peaks are needed. Furthermore, the frequency resolution of the EPPD is independent of the number of data available and of the sampling frequency.

Electroencephalography↗