[Show abstract][Hide abstract] ABSTRACT: Objectives:
In the present study, we aimed to clarify the specific effects of age, period, and cohort on trends in obesity rate and energy intake ratio from fat in Japanese adults using a Bayesian age-period-cohort (APC) analysis and to evaluate the relationship between changes in obesity rate and energy intake ratio from fat.
We obtained data regarding obesity rate and calorie intake of fat, animal fat, carbohydrate, protein, animal protein, and total energy intake of Japanese adults from the National Nutrition Survey. The data were tabulated for five 10-year age groups (from 20-29 years to 60-69 years) and 17 annual demographic profiles (from 1995 to 2011), with regard to the energy intake ratio. These standard cohort tables were analyzed using a Bayesian APC model.
With regard to obesity rate, the effect of age was the greatest and increased rapidly in the age group of 30-39 years for both genders. Moreover, the period effect consistently increased in men, but had very little variation in women. The cohort effect indicated a reverse of the decreasing trend in the cohorts born after 1962-1971 in men and indicated a reverse of the increasing trend in the cohorts born after 1965-1974 in women. With regard to the energy intake ratio from fat, the trends for the three effects differed from those for obesity rate for both genders. The age effect generally decreased with increasing age. Furthermore, for both genders, the period effect gradually decreased after 1998 and markedly decreased in 2001, remained constant or slightly increased until 2008, and increased thereafter. However, the cohort effect was the greatest among the three, and although a decreasing trend was observed in the cohorts born after 1976-1985 in women, the energy intake from fat increased in the younger cohorts in both genders. The overall effect on energy intake ratio from animal fat had a slope similar to that of the energy intake ratio from fat.
Each effect affected obesity and energy intake ratio from fat in a different manner, suggesting that factors other than energy intake ratio from fat, such as energy expenditure, contributed to the changes in obesity rate. However, obesity risk markedly increased in the age group of 30-39 years, and younger generations had a higher energy intake ratio from fat. These results suggest that dietary guidelines, particularly the optimal intake of animal products, is needed for younger generations to prevent the development of obesity in adulthood.
No preview · Article · Oct 2014 · [Nippon kōshū eisei zasshi] Japanese journal of public health
[Show abstract][Hide abstract] ABSTRACT: Objectives:
We aimed to determine the effects of age, period, and birth cohort on cervical cancer mortality rate trends in Japanese women, by age-period-cohort (APC) analysis. Additionally, we analyzed projected mortality rates.
We obtained data on the number of cervical cancer deaths in Japanese women from 1975-2011 from the national vital statistics and census population data. A cohort table of mortality rate data was analyzed on the basis of a Bayesian APC model. We also projected the mortality rates for the 2012-2031 period.
The period effect was relatively limited, compared with the age and cohort effects. The age effect increased suddenly from 25-29 to 45-49 years of age and gently increased thereafter. An analysis of the cohort effect on mortality rate trends revealed a steep decreasing slope for birth cohorts born from 1908-1940 and a subsequent sudden increase after 1945. The mortality rate projections indicated increasing trends from 40 to 74 years of age until the year 2031.
The age effect increased from 25-29 years of age. This could be attributable to the high human papilloma virus (HPV) infection risk and the low cervical cancer screening rate. The cohort effect changed from decreasing to increasing after the early 1940s. This might be attributable to the spread of cervical cancer screening and treatment before 1940 and the high HPV infection risk and reduced cervical cancer screening rate after 1945. The projected mortality rate indicated an increasing trend until the year 2031.
No preview · Article · Sep 2014 · Nippon Eiseigaku Zasshi (Japanese Journal of Hygiene)
[Show abstract][Hide abstract] ABSTRACT: Objectives:
The increase in the overweight or underweight student population in Japanese schools is an important health issue. To assess the independent effects of age, period, and birth cohorts, we analyzed trends in the rates of overweight and underweight students from 1977 to 2006 using a Bayesian age-period-cohort (APC) analysis. Additionally, we predicted the rates overweight and underweight students in 2007-2016.
We created a data set of the rates of overweight and underweight students aged 6-14 years using the annual school health survey report data. We then analyzed a cohort table that plotted age against calendar time using a Bayesian APC model. We also made a prediction of the rates of overweight and underweight students in 2007-2016.
For overweight students, the age effect increased from 6 to 11 years of age for male students and from 6 to 12 years of age for female students; thereafter, the effects decreased. The period effects consistently increased until late 1990, and decreased thereafter for both male and female students. The cohort effects increased for male students born between 1963 and 1969, and later decreased for those born in 1981. However, this trend for male students later increased. For female students, the cohort effects decreased for those born between 1963 and 1975, and later increased for those born in 1990, indicating a plateau or slight increase in the trend. For underweight students, the age effect in male students increased from 7 to 10 years of age, and then plateaued; whereas, the age effect increased from 7 to 12 years of age for female students before reaching a plateau. The period effects increased consistently by 2000 and decreased slightly in both male and female students. The birth cohort effect in male students increased for those born after the mid-1980s, and then plateaued in the early 1990s. The cohort effect increased for female students born after 1984, and then plateaued in 1993. The projections for the rates of overweight and underweight student population indicated a steady trend until 2016.
The rate of overweight and underweight students was strongly influenced by age; however, period and birth cohort also played a role. The projections for the rates of overweight and underweight students indicated a steady trend until 2016. These results suggest that strategies based on age-, period-, and cohort-specific measures may be required for future interventions for preventing overweight and underweight among students.
No preview · Article · Jun 2013 · [Nippon kōshū eisei zasshi] Japanese journal of public health
[Show abstract][Hide abstract] ABSTRACT: To determine the age-, period-, and cohort-specific effects on the male proportion in Japanese newborns, we performed an age-period-cohort (APC) analysis in this study. In addition, projections for the male proportion were analyzed.
We obtained data on live births of newborns for Japanese women in 1947-2007 from the National Vital Statistics. Cohort tables containing data on the male proportion were analyzed using a Bayesian APC model. Projections of the male proportion (2008-2027) were calculated.
The age effect decreased when the mothers were 40-44 years old; however, the effect was relatively limited as compared with the period and cohort effects. The period effect increased from 1947 to 1969 and decreased thereafter. Analysis of the cohort effect on male proportion trends revealed a decreasing slope for birth cohorts born between 1905 and 1945 and a subsequent increase after 1958. The projections for male proportion indicated that the male proportion in 2027 would be similar to that in the 1970s.
The age of the mother hardly affected the male proportion. The period effect started decreasing from the latter half of the 1960s. This may be attributable to the high economic growth since 1965 that promoted industrial development that led to environmental pollution, which in turn may have lead to the deterioration of the intrauterine environment. Cohort effects changed from 1958 and exhibited trends toward increase in male proportion; this may be due to improvements in obstetric care. Our results suggest that the male proportion in Japanese newborns will increase in the future.
No preview · Article · May 2011 · Nippon Eiseigaku Zasshi (Japanese Journal of Hygiene)
[Show abstract][Hide abstract] ABSTRACT: Because suicide is increasingly becoming a public health threat in Japan, it is necessary to identify high-risk groups to develop effective preventive measures. The suicide mortality trends from 1985 to 2006 for Japanese aged between 15 and 79 years were analyzed by a Bayesian age-period-cohort analysis to evaluate the independent effects of age, period, and birth cohort. Age-specific effect showed an overall increase with age in both genders, but a distinct increase was noted only among men aged between 50 and 64 years. The period effect exhibited a sudden rise in 1998; this effect was more apparent in men than in women. The cohort-specific effect increased in male birth cohorts born after 1926 and in female birth cohorts born after 1956. In conclusion, a gender difference was detected in the effects of age, period, and cohort on suicide risk among Japanese.
No preview · Article · Oct 2009 · Asia-Pacific Journal of Public Health
[Show abstract][Hide abstract] ABSTRACT: An age-period-cohort (APC) analysis was performed to provide information about age-, period-, and cohort-specific effects on marriage trends in Japanese women. In addition, the relationships of the trends of age-, period-, and cohort-specific effects between marriage and birth were analyzed.
We obtained data regarding marriages of Japanese women aged between 19 and 38 years for the period of 1985 to 2005 from the National Vital Statistics. Population data used were for an estimated population, obtained from the Population Estimates Annual Reports. Standard cohort tables comprising marriage and population data were analyzed using a Bayesian APC model to identify age-, period-, and cohort-specific effects on marriage rate trends. Previously obtained data for a similar APC-analysis of birth trends were used to compare the trends in the effects of age, period, and cohort on marriage and birth patterns. For this purpose, the estimated values for each effect were normalized.
With regard to the marriage trends in Japanese women, the effect of age was the greatest, peaking at the age of 25 years. The period effect increased after 1997; however, its effect was relatively limited as compared to the other effects. The cohort effect, which was greater than the period effect and less than the age effect, on marriage trends showed a decreasing slope for birth cohorts born after 1966 and subsequent increase after 1982. Comparison of age, period and cohort effects between the trends in marriage and birth rates showed that the age effect distinctly peaked at 25 and 28 years for marriage and births, respectively. The period effect on marriage and birth showed a decreasing trend until 1991 and subsequent increased in 1992 and 1997 for births and marriage, respectively. With regard to the cohort effect on birth rates, a decreasing trend was observed for the birth cohorts after 1961, with increase after 1977. However, with regard to the cohort effect on marriage rates, the decreasing trend observed for birth cohorts after 1966 showed an increase after 1982.
Among age, period, and birth cohort, age is the most influential factor affecting marriage rates. Period effects appear relatively small, but they increased after 1997. Cohort effects reduced for birth cohorts born after 1966 and subsequently increased after 1982. Results of the comparison study showed that changing patterns of age, period and cohort effects had very similar influences on the trends for marriage and birth rates. However, a 3-year difference was observed between the peaks of the age effect on the two rates. A time lag of 5 years was observed between the turning point in the trend of period effects for marriage and birth rates. The changing patterns of cohort effects on marriage and birth rates were similar, but the turning point for the marriage pattern occurred in a 5-year younger cohort compared with the birth pattern.
No preview · Article · Aug 2008 · [Nippon kōshū eisei zasshi] Japanese journal of public health