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At least 19 recordsLinked to original sources
PubMed1979

[Correlations between the secular trend in sugar consumption in England and the secular increase of brain weight in adults in London between 1860 and 1940].

Significant positive correlations exist between the secular increase in brain weight of adults in London born between 1860 and 1940, and the secular trend in sugar consumption in the United Kingdom. These results of statistical analysis confirm once again the important bearing of excessive sugar consumption on the development of pre- and postnatal growth acceleration. The pathophysiological interactions of this development are discussed in the light of the experimentum naturae of the IDM (infant of the diabetic mother) and an attempt is made to explain the difference in brain weight increase between males and females.

Anthropometry↗
PubMed1990

Research on secular trends in auxology.

Current status of research on secular trends in growth and maturation is considered from several perspectives. The need to define secular trends as positive, negative or absent is initially discussed. Positive secular trends, i.e., increases in size and earlier maturation, characterize the majority of the auxological literature. However, some populations have experienced negative secular trends or no trends. Positive secular trends and cessation of secular trends in stature and age at menarche are described for developed countries, followed by a brief discussion of secular changes in body proportions and composition. Data from developing countries illustrate all three types of secular trends. Some segments of the population show positive changes in size and age at menarche, while others show no evidence of secular change or negative secular trends. Finally, comparisons of estimated statures in earlier European populations suggest a negative secular trend, i.e., a decline in estimated stature from about the 11th to the 19th centuries, which is followed by a positive secular trend starting about the mid-19th century.

Adolescent↗
PubMed1979

Secular trends in human growth, maturation, and development.

Rates of growth during childhood have increased considerably during the past 50-100 years. Because they are associated with increased rates of maturation, these size increases are maximal at ages when recently measured groups are pubescent but those measured in the past had not reached pubescence. Large secular increases in rates of growth and maturation have occurred in all developed countries but not in many other countries. There have been secular increases in recumbent length at birth in Italy and France but little change in the United States. The secular increase in childhood stature is much more obvious, being about 1.5 cm/decade for 12-year-old children, although for young adults the secular increase in stature has been about 0.4 cm/decade in most developed countries. In the United States these trends have been similar for blacks and whites during childhood but greater for black men than white men. Similarly, secular trends in birth weights have been small, but there have been large trends for children (about 1.5 kg/decade for 12-year-olds). These secular changes in size have been associated with an acceleration of maturation that is most evident in the 0.3 years/decade advancement in age at menarche. This advancement has now ceased in Norway and England. The changes in body proportions during recent decades are less marked than those in body size. Leg length, particularly the length of the thigh, seems to have increased more than stature in men but not women; chest circumference has increased more rapidly than stature in each sex. The relationships between stature and weight have changed in different ways in various national groups. Similarly, the relative changes in head length and head breadth vary with the groups studied. Few sets of data allow conclusions about possible secular trends in body composition, but subcutaneous fat thicknesses have increased, especially at the upper percentiles. Also strength, which reflects muscle mass, has increased absolutely, although it has decreased relative to stature. Undoubtedly the secular trend is due to various factors; the identification of causes is necessarily speculative. Changes in nutrition alone could not account for the trends which exceed the original socioeconomic differentials. In the United States, there have been per capita increases in the intake of protein and fat from animal sources, decreases in carbohydrates and fat from vegetable sources, and little change in caloric intake. It is not clear that these changes constitute better nutrition. The secular trends could reflect environmental improvements, specifically changes in health practices and living conditions leading to improvements in mortality rates and life expectancy. These factors are interrelated with those concerning family size. Also genetic factors, especially heterosis, may have played a small role in causing the secular trends...

Body Composition↗
PubMed1975

Stature and secular trend among Southern African Negroes and San (Bushmen).

Despite a wide belief that little information is available on the dimensions of Southern African peoples, data for adult mean stature are presented for no fewer than 123 samples of S.A. Negro (93) and Khoisanoid (30) peoples. Many are published here for the first time. These have made possible a search for signs of the secular trend towards increased adult stature. Two main techniques are the study of longitudinal data (where time-spaced studies on the same population are available) and of age-ranked, cross-sectional data (where the lack of declining stature with age connotes the absence of a secular trens). Most Southern African populations for which data are available show either the absence of the secular trend (previously recognized) or a frankly reversed secular trend (a new concept), in which adults show a decline in mean stature compared with earlier generations. Similar absence or reversal of the secular trend characterizes peoples in Malawi, Kenya, Uganda, Sudan, Senegal, Upper Volta and Ivory Coast, as well as some Asian and South American samples. In the main, developed areas show the secular trend, while less developed areas show an absence or reversal of the trend. To this generalization, the San are a striking exception. All the evidence, first adduced in 1962, points to the usual secular trend as occurring in the San, despite their lowly, undeveloped economic status. Although the data are imperfect, it is possible too, that Xhosa and Moçambique Maravi show evidence of a positive secular trend. "The adult form of mankind is the outcome of growth enhanced, dwarfed, warped, or mutilated by the adventures of life. I am not decrying heredity. But I do insist that new knowledge gained for anthropology through the study of growth brings hope and confidence where formerly was only the grim figure of destiny." (T. Wingate Todd, 1935).

Adolescent↗
PubMed1999

Secular change in long bone length and proportion in the United States, 1800-1970.

We examine secular change in long bone lengths and allometry of Americans dating from the mid-19th century to the 1970s. Skeletal samples were derived from the Huntington Collection, Terry Collection, World War II casualties, and the Forensic Anthropology Data Bank. Regression of bone length on year of birth allowed evaluation of the secular change in bone length. Size was computed as the geometric mean of all bone lengths, and shape as the ratio of each bone to size. These variables were then regressed on year of birth, allowing evaluation of allometric secular change. The results revealed a pattern of change that can be summarized as follows: male secular change is stronger than female, lower limb bone secular change is more pronounced than upper limb bone change, and distal bones change more than proximal bones, particularly in the lower limb. In males, white changes are uniformly higher than black but these differences do not rise to the level of statistical significance. Environmental forces, such as nutrition and disease, are the usual causes of secular changes in overall size. This paper shows that long bone proportions also respond to these same environmental factors. Moreover, the changes in body proportion are likely to be due to allometric consequences of growth changes that occur early in life. Am J Phys Anthropol 110:57-67, 1999.

Anthropometry↗
PubMed2000

Secular trend in body height and weight of Australian children and adolescents.

Secular changes in growth and maturation have been well documented in various world populations, with secular increase especially noticeable in the developed countries. To assess the trend in both adult size and tempo of growth we compared the data on stature and body weight obtained in 1992-1993 from 1,804 Melbourne school students aged 5 to 17 with historical data collected from white Australians during the last 100 years. We illustrate the age-dependent trend in stature and body weight by means of regression surfaces. These were constructed by fitting local regression models to historical data and by simple plots showing the overall, and per decade, secular increase in both these measures at peripubertal and adult ages. Because of limited information on sample sizes and variability provided by the historical data, statistical comparisons have been performed only between the present 1992-1993 survey and two earlier independent surveys conducted in 1985 and 1970. The results have shown secular increase in adult stature over the last century, with the rate of increase varying between 0.4 and 2.1 cm/decade in males and 0.01 and 1.6 cm/decade in females. While secular increase in stature has significantly slowed down during the last two decades, the increase in body weight is still continuing at a high rate, and this increase is more pronounced in females. The period of strong secular increase, especially in the tempo of growth, coincided both with the shift toward earlier menarche and the improvement of socioeconomic conditions of the Australian population. The need for further studies to identify factors determining the continuing increase in body weight is emphasized, and caution in using the existing national growth standards for stature and weight is recommended.

Adolescent↗
PubMed1980

Secular trend in the stature and weight of Mexican-American children in Texas between 1930 and 1970.

Statures and weights for four samples of Mexican-American children in Texas, measured in 1929-1931 and 1968-1972, were evaluated for evidence of a secular trend. The age range was 6 to 18 years, with more complete data from 8 through 15 years. There is no secular increase in the statures and weights of 6 year old children, a small increase in 8 year old children, and a larger secular increase at 10, 12, 14, and 15 years of age. From about 9 or 10 years of age on, the more recent Mexican-American children tend to have greater weights for their heights. The magnitude of the secular change per decade, however, is considerably smaller than rates for US black, white, European, and Japanese children. The estimated rates of secular change in stature for Mexican-American children approximate about one-fourth to one-half of the generalized rates for European and North American children offered by Meredith ('76) and Tanner ('77). Reasons for a limited secular trend in Texas Mexican-American children are probably bound to the matrix of lower socioeconomic circumstances, poorer health conditions, and marginal nutritional status.

Adolescent↗
PubMed1999

A sensitivity analysis of secular trends in risk factors and mortality based on cohort studies.

Because of a "healthy responder effect," secular trends in mortality based on cohort studies may be biased if based on responders only. Because responders are selected on the basis of their health at study entry, subjects just entering a study are not comparable with subjects who have been in the study for several years. The result may be an artificial increase in mortality, which impedes analyzing the effect of secular trends in risk factors on mortality. The objective of this paper is to suggest a solution by using data on nonresponders and applying a sensitivity analysis. We illustrate this solution with data on trends in smoking prevalence and all-cause mortality based on a large Danish cohort study with 19 years of complete follow-up on responders and nonresponders. Secular trends in mortality based on the whole sample vs responders only illustrated that results based on responders were biased. In a sensitivity analysis, the observed person-years of nonresponders were distributed among six categories of persons with respect to smoking behavior (never-smokers; ex-smokers; noninhaling current smokers; and current smokers of 1-14, 15-24, and > or =25 gm tobacco per day) according to preset assumptions regarding smoking habits. The observed deaths among nonresponders were then distributed on the six smoking categories according to relative risks derived from a Poisson regression analysis among responders. This procedure allowed us to study the effect of adjustment for smoking on the unbiased secular trend in mortality. By applying different assumptions regarding smoking habits among nonresponders, we explored the effect of the assumptions on the adjusted secular trend in mortality. We conclude that secular trends in mortality based on responders in a cohort study are likely to be biased. If complete follow-up on nonresponders is available, this method could prove useful in other cohort studies.

Aged↗
PubMed1990

Secular changes in stature in southern Portugal between 1930 and 1980 according to conscript data.

Stature of conscripts from four regions of southern Portugal was evaluated in a secular perspective. Data were drawn from the draft records for each decade between 1930 and 1980, a period that corresponds to a decisive expansion of industry and urbanization. In each region conscripts were divided into two groups according to their area of birth: urban or rural. A secular shift was apparent in every region, affecting conscripts of both urban and rural extraction. However, gains in stature were greater in the littoral than in the hinterland regions, where agriculture still employs a large percentage of the population. In each region the urban conscripts experienced greater secular gains than their rural counterparts. The secular shift was more pronounced among the short-stature segments of the populations; percentages of conscripts below a height of 160.0 cm dropped in a striking manner throughout the period under investigation. Despite the paucity of reliable information on the anthropometric and biodemographic characteristics of the Portuguese population, the secular gains were found to be associated with infant mortality and total death rate in the four regions. Compared to other Western European populations, the secular growth of the Portuguese proceeds at a slower pace, even when comparisons are made within the group of Latin countries that share a common linguistic and cultural heritage in addition to the shortest statures in Europe.

Body Height↗
PubMed1984

Age-specific variation in the secular trend for stature: a comparison of samples from industrialized and nonindustrialized regions.

Age-specific secular trend patterns for children in industrialized world regions have a regular pattern, beginning low at age 6 and increasing to a maximum at age 10 to 14, then declining. While magnitude differs, the patterns are ordinarily parallel, especially in the female samples. However, age-specific secular trend values for children from developing regions, or from areas of industrialized countries not benefitting substantially from development, are irregular in pattern and magnitude. Consequently, it is difficult to predict age at maximal secular change. We suggest that fluctuating environmental circumstances in these developing countries influence growth and, hence, the pattern of secular trend. As more stable environmental conditions relating to growth are present in the industrialized countries, this leads to more stable patterns of growth and age-specific patterns of secular change.

Adolescent↗
PubMed1999

The paucity of effects in community trials: is secular trend the culprit?

BACKGROUND: The most recent major U.S. trials that evaluated community-level programs to influence risk factors and health behaviors identified secular trends in the risk factors and health behaviors among the factors that might have limited community-level effects. The research reported in this paper uses data from one of the trials to examine the secular trend explanation directly. METHODS: Data from the 22-community Community Intervention Trial for Smoking Cessation (COMMIT) were analyzed to test a hypothesis based on secular trend reasoning: program effects for smoking prevalence were larger for treatment communities matched to control communities with small declines in smoking than in treatment communities matched to control communities with larger declines in smoking. RESULTS: Consistent with the secular trend explanation, program effects were larger when control communities had relatively small declines in smoking prevalence. CONCLUSIONS: The findings suggest that secular trends masked community-level program effects in COMMIT.

Canada↗
PubMed1993

Natural history of idiopathic dilated cardiomyopathy: effect of referral bias and secular trend.

OBJECTIVES: The current study was designed to determine the effect of secular trend and referral bias on the natural history of idiopathic dilated cardiomyopathy. BACKGROUND: In a previous study of 104 patients with idiopathic dilated cardiomyopathy conducted in a referral population at the Mayo Clinic between 1960 and 1973, the 1- and 5-year mortality rates were 31% and 64%, respectively. A recent study of 40 patients with idiopathic dilated cardiomyopathy conducted in a population-based cohort at the Mayo Clinic between 1975 and 1984 reported 1- and 5-year mortality rates of 5% and 20%, respectively. We hypothesized that improvements in diagnosis and therapy have occurred since the original referral cohort was described and that these improvements have altered the apparent natural history of the disease. We refer to this effect as secular trend. Alternatively, the presence of more advanced disease in the referral population (referral bias) may also contribute to the differences in survival. METHODS: Two sequential referral populations with idiopathic dilated cardiomyopathy seen at the Mayo Clinic between 1976 and 81 (n = 85) and 1982 and 1987 (n = 137) were identified. Outcome was compared between these cohorts and the 1960-1973 referral cohort to examine the effect of secular trend. Outcomes were compared with that of the population-based cohort to examine the effect of referral bias. RESULTS: Survival in the 1976-1981 referral cohort did not differ from that in the 1960-1973 referral cohort, suggesting little impact of secular trend during these time periods. Survival in the more recent 1982-1987 referral cohort was significantly better than that in the earlier referral cohorts, suggesting that improvements in diagnosis and treatment in the 1980s altered the natural history of idiopathic dilated cardiomyopathy. Survival in the 1982-1987 referral cohort was still worse than that of the population-based cohort, suggesting an effect of referral bias on studies of the natural history of idiopathic dilated cardiomyopathy. CONCLUSIONS: The current study demonstrates that secular trend and referral bias affect the apparent natural history of idiopathic dilated cardiomyopathy. Survival in referral patients with this disease is significantly better than previously described.

Bias↗
PubMedDate not supplied

Secular trends in height, weight and body mass index of 6-year-old children in Bremerhaven.

Secular trends in growth processes of children can be important indicators of changes in public health. Common to studies on secular trends in children is that evaluation is based on comparison of data collected at two (or more) distinct points on a time scale. The quantitative characteristic of the secular trend is estimated by linear interpolation between the two end points of the underlying time interval, which in studies of children are usually at least 10 years apart. The purpose of the present paper is to analyse secular trends in height, weight and body mass index (BMI) of 6-year-old children from Bremerhaven over the period 1968-1987 (the year refers to the birth cohort). The results are based on data drawn from health records of the City Health Centre, where all 6-year-old children are routinely measured in a school entrance examination. Thus the data represent complete birth cohorts of children entering school in Bremerhaven and not selected samples. The data reported here refer only to children of German origin. The sample sizes vary from n = 313 (girls born in 1982) to n = 737 (boys born in 1968), and total sample size is n = 7601. Regression of the arithmetic means of height on year of birth showed that the trend in stature for children born between 1968 and 1987 was 0.67 cm/decade for boys and 0.49 cm/decade in girls. Both trends are statistically significant (p < 0.05). Although there was an increasing tendency for weight as well, which was more marked for the 95th percentile than for the median, neither of the trends in both sexes was statistically significant. While the BMI in both sexes showed no trend at all for the median and the 5th percentile, there was a significant linear increase of the 95th percentile. Furthermore, the results for height show that an evaluation of secular trends under qualitative and quantitative perspective critically depends on the selection of points on the time scale.

Body Constitution↗
PubMedDate not supplied

Secular trend in birthweight among the Purari delta population, Papua New Guinea.

The aim of this analysis was to examine the extent and possible seasonal nature of the secular trend in mean birthweight in the Purari delta, Papua New Guinea. This is a country undergoing rapid modernization, and with this has come a secular trend toward increased adult body size in some parts of the country but not others. Birthweight data, collected by month of delivery at Kapuna Hospital in the Purari delta between the years 1969 and 1996, was analysed by year of birth and by season, using one-way analysis of variance and post hoc Scheffé tests with the statistical software SPSS-PC+. A total of 927 birthweights for the years 1969, 1972, 1977, 1994 and 1996 were included in the analysis. Twin births were excluded from analysis, as were births below 1.5 kg. There is clear evidence of a secular trend in increasing mean birthweight between the period 1969 and 1996, with the largest significant difference being between 1977 and 1994, from 2.70 to 2.92 kg. There were no significant differences in mean birthweight between the sexes. The rate of birthweight increase between 1977 and 1994 was 130 g per decade, lower than the gain of 200 g per decade in the period 1994-1996. The decline in birthweight of 90 g per decade during the period 1969-1977 is not statistically significant. The proportion of infants born with low birth weight (< 2.5 kg) shows an increase between 1969 and 1972, and a decline thereafter. While seasonal differences in birthweight during any of the years examined is non-significant, significantly greater mean birthweight across the period 1969-1996 was found for births during the wet season (April to July), and the drier season (August to November), respectively. The secular increase in mean birthweight is likely to be a consequence of the improvements in maternal diet and increased maternal body size that have come with economic modernization. The secular trend of seasonality in mean birthweight among the Purari delta population may be a function of seasonally varied displacement of traditional diet by non-local bought foods, as well as reduced seasonality of maternal workload associated with the processing of the traditional staple food.

Agriculture↗
PubMed1988

Secular trends in body mass in the United States, 1960-1980.

Data from four National Health Examination Surveys conducted of the US population from 1960 to 1980 were analyzed to determine secular trends in obesity for white and for black adolescents and young adults of both sexes. Body mass index was categorized into four levels using cut points determined by the 50th, 75th, and 85th percentiles at the first survey in 1960-1962. The weighted proportions of persons in these body mass categories were determined, and statistical models were developed to describe secular trend and race effects. No consistent secular trends were found for white or black youths aged 12-17 years. No significant secular trends in obesity were found for white or black young males aged 18-34 years. Both for white and for black adult females, there were significant secular increases in the proportion of adult females in each of the successively heavier categories of body mass index. These increases were identical for white and for black adult females on the log-odds scale, but black adult females were already significantly heavier at the first survey. This race effect persisted throughout the entire time interval.

Adolescent↗
PubMed1997

Secular changes in growth and maturation: an update.

Secular changes in growth and maturation in recent decades have been reviewed for various populations. The secular increase in attained height during the growth period is continuing in most countries, but has slowed down. The increase in adult stature over the past decades has varied between 0.3 and 3.0 cm/decade. The secular trend in the tempo of growth (earlier menarche and peak height velocity, and shortening of the growth cycle) has come to a halt in some populations, but is continuing or has been reversed in others. The secular trend in attained height and in the tempo of growth is usually more pronounced in children from low socioeconomic backgrounds, in those with poorly educated parents or in those from rural areas. It is concluded that updates of growth standards are required in all populations. More marked secular changes appear to occur in the lower height centiles, which may have direct implications on the future definition of 'short stature' in a population.

Body Height↗