Health perceptions and survival: do global evaluations of health status really predict mortality?

Self-evaluations of health status have been shown to predict mortality, above and beyond the contribution to prediction made by indices based on the presence of health problems, physical disability, and biological or life-style risk factors. Several possible reasons for this association are discussed: (a) methodological shortcomings of previous studies render the association spurious; (b) other psychosocial influences on mortality are involved and explain the association; and (c) self-evaluations of health status have a direct and independent effect of their own. Four-year follow-up mortality data from the Yale Health and Aging Project (N = 2812) are used to explore these possibilities. The analysis controls for the contribution of numerous indicators of health problems, disability and risk factors, and also makes adjustments of standard errors for the complex sample design. The findings favor the third possibility, an independent effect, to the extent that the particular set of psychosocial factors examined did not explain the basic association, and to the extent that the control variables were an adequately comprehensive set.

Using significance tests to evaluate equivalence between two experimental groups

Equivalency testing, a statistical method often used in biostatistics to determine the equivalence of 2 experimental drugs, is introduced to social scientists. Examples of equivalency testing are offered, and the usefulness of the method to the social scientist is discussed.

Demography of the Hadza, an increasing and high density population of Savanna foragers

This is a report on the demography of the Hadza, a population of East African hunter-gatherers. In it, we describe the results of a census, and our estimation of age structure, survivorship, mean age of women at childbearing, number of live children, total population size and density, and rate of change since 1967. We show that relevant measures fit closely the stable population model North 6 chosen by Dyson to represent Hadza demography in the 1960s. We compare aspects of Hadza demography with surrounding non-Hadza and with the !Kung. Among other things, we find that the Hadza have a higher population density, higher fertility, and a faster population growth rate than do the !Kung. These demographic differences are consistent with our expectations, which were based on differences in the costs and benefits of foraging in the two regions. We also show that Hadza demographic parameters display remarkable consistency over the past 20 years. Since neighboring populations have been encroaching on the area used by the Hadza, and Hadza foragers have been subject to interludes of externally imposed settlement, this consistency is surprising. We discuss some of the implications.

Seasonality of reproductive function and weight loss in rural Nepali women

Menstrual and hormonal disturbances have been reported in thin, dieting and exercising Western women, and also recently in rural African women. A study of salivary progesterone profiles was undertaken in a Nepali population to examine whether seasonal increases in workload and changes in energy balance influenced ovarian function. Women's energy expenditure levels were moderately heavy in the winter and very heavy in the monsoon, and body mass fluctuated by -2.8 to +4.8 kg. Samples were collected from 24 normally menstruating women in two seasons, each individual serving as her own control. Progesterone levels were significantly depressed in the monsoon relative to winter for women who lost weight, but not for women who gained weight, indicating that energy imbalance is associated with a loss of fecundity. No differences in body mass index were found between women who lost or gained weight. Progesterone levels were age-dependent, and the degree of hormonal disturbance between age-groups was related to weight loss. The study demonstrates seasonal changes in the fecundity of hard-working Nepali women and a direct link between ovarian function and weight loss (negative energy balance), which is independent of current nutritional status.

The ecology of birth seasonality among agriculturalists in central Africa

The Lese are subsistence farmers living in the Ituri Forest of north-east Zaïre. They exhibit significant birth seasonality, with lowest frequencies of conception when food production is least, nutritional status is low and ovarian function, as measured by salivary steroid hormone levels, is reduced. Efe pygmy foragers, who live in the same geographical area but are less dependent on cultivated foods and have a more flexible life style, do not exhibit frequent fluctuations in nutritional status nor significant birth seasonality. These findings support a model of birth seasonality relating climatic variables to variation in fertility through a causal chain linking rainfall to food production to energy balance to ovarian function to fertility. The model, which emphasises an ecological approach to the study of human reproduction, should have broad applicability since seasonality of food production and energy balance is widespread geographically and across a wide variety of economies and cultures.

Paleodemography: expectancy and false hope

From parent populations (N = 50,000) stochastically generated, representing different levels of correlation (r) between the age at death and a hypothetical biological indicator (r = 0.8-0.98), reference samples and target demographic samples are randomly drawn. Two iterative techniques, proportional fitting procedure and Bayesian, are used to estimate from the reference samples the age distribution of the targets. Due to the random fluctuations of the pattern of aging, both in the reference and target samples, these techniques converge only in expectation toward the true value of a distribution, but not in practice for any particular realization. Nevertheless, these techniques allow the estimation of the average of an age distribution, even if its shape is unknown. Under the hypothesis that the target sample is drawn from a stationary population, this average represents the life expectancy at 20 years (plus 20 years). Using this mean age at death for the adults and the juvenility index at death (D5-14/D20-omega), a new set of paleodemographic estimators were derived from 40 archaic life tables. For a hypothesized stable population, they give the life expectancy at birth and at 20 years, and the probability of death at 1 and 5 years.

World population growth, family planning, and American foreign policy

The U.S. government position on world population growth as it emerged in the early 1960s was a fundamental departure in both content and commitment. We embraced the idea that one of the goals of American foreign policy should be the simultaneous reduction of both mortality and fertility across the Third World. It was not simply rhetoric. As the years passed, we committed a growing portion of our foreign aid to that end. The decision to link U.S. foreign-policy objectives with the subsidy of family planning and population control was truly exceptional in that it explicitly aimed at altering the demographic structure of foreign countries through long-term intervention. No nation had ever set in motion a foreign-policy initiative of such magnitude. Its ultimate goal was no less than to alter the basic fertility behavior of the entire Third World! Whether one views this goal as idealistic and naive or as arrogant and self-serving, the project was truly of herculean proportions.

The origins and development of the diffusion of innovations paradigm as an example of scientific growth

This article traces the emergence of the basic paradigm for early diffusion research created by two rural sociologists at Iowa State University, Bryce Ryan and Neal C. Gross. The diffusion paradigm spread to an invisible college of midwestern rural sociological researchers in the 1950s and 1960s, and then to a larger, interdisciplinary field of diffusion scholars. By the late 1960s, rural sociologists lost interest in diffusion studies, not because it was ineffective scientifically, but because of lack of support for such study as a consequence of farm overproduction and because most of the interesting research questions were thought to be answered.

Seroprevalence of HIV infection in rural South Africa

OBJECTIVES

To establish the prevalence of HIV infection in rural South Africa and to investigate demographic factors that influence this prevalence.

DESIGN

An anonymous HIV seroprevalence survey was performed in conjunction with a population-based malaria surveillance programme.

SETTING

The rural area of northern Natal/KwaZulu, South Africa.

PARTICIPANTS

A total of 5023 black African participants were recruited by malaria surveillance agents during house-to-house visits; each house in an endemic malaria area is visited approximately once every 6 weeks. Participants included 4044 healthy and 979 febrile individuals (i.e., suspected of having malaria).

MAIN OUTCOME MEASURES

HIV-1 and HIV-2 serological status, degree of mobility, age and sex.

RESULTS

Sixty of the 5023 blood specimens were confirmed to be HIV-1-antibody-positive by Western blot, an overall prevalence of 1.2% (95% confidence interval, 0.9-1.5). None of the specimens was positive for HIV-2 antibodies. After adjusting for age, presence of fever and migrancy, women had a 3.2-fold higher prevalence of HIV-1 infection than men. HIV-1 infection was approximately three times more common among subjects who had changed their place of residence recently (2.9 versus 1.0%, P < 0.01).

CONCLUSIONS

The prevalence of HIV-1 infection is higher among women than men resident in rural Natal/KwaZulu, South Africa. This is at least in part the result of oscillatory migration, particularly of men who work in urban areas but have families and homes in rural areas. Migration is associated with a higher prevalence of HIV-1 infection, suggesting that improving social conditions so that families are not separated and become settled in their communities is one way to help reduce the spread of HIV-1.

Social and cultural aspects of infertility in Mozambique

Findings of an anthropological study of socio-cultural aspects of infertility among members of the matrilineal ethnic group Macua in the north of Mozambique are presented. Infertile women apply various strategies to have a child. Traditional healers are visited much more often than the modern hospital, and the explanations the infertile women themselves give for their infertility more often originated from the traditional healers than from the hospital staff. Almost all of the interviewed women commit adultery in the hope to conceive. Some of them apply fostering as a partial solution for childlessness. The Macua infertile women experience various consequences due to their infertility, of which exclusion from certain social activities and traditional ceremonies is perceived as a very problematic one. The matrilineal kinship system means that the husband and his family do not mistreat and repudiate her. Infertility must be considered as a serious reproductive health problem in Mozambique. For the long term preventive measures may be more influential than curative one. The findings of this study can be used to elaborate culturally sensitive health education programmes.

The long-term pattern of adult mortality and the highest attained age

"Recent new data on old age mortality point to a particular model for the way in which the probability of dying increases with age. The model is found to fit not only modern data but also some widely spaced historical data for the 19th and 17th centuries, and even some estimates for the early mediaeval period. The results show a pattern which calls for explanation. The model can also be used to predict a probability distribution for the highest age which will be attained in given circumstances. The results are relevant to the current debate about whether there is a fixed upper limit to the length of human life." A discussion of the paper by several researchers and a reply by the author are included.

Congenital syphilis in the past: slaves at Newton Plantation, Barbados, West Indies

Hutchinson's incisors and Moon's molars are specific lesions of congenital syphilis. The extensive but fragmentary clinical literature on these conditions describes reduced dimensions and thin enamel in the permanent incisors and first molars, crowding and infolding of the first molar cusps, notching of the upper incisors, and apical hypoplasias of the permanent canines. A Barbados slave cemetery (ca. 1660-1820 AD) includes three individuals with these features, suggesting a frequency at birth of congenital syphilis in the population approaching 10%. These three cases show triple the frequency of all hypoplasias and more than seven times the frequency of pitting hypoplasia present in the remainder of the series. The recognizable congenital syphilis cases account for much of the remarkably high frequency of hypoplasias in the series as a whole. We infer that syphilis contributed substantially to morbidity, infant mortality, and infertility in this population. Presence or absence of congenital syphilis may account for much of the variability in health and mortality seen among nineteenth century African-American populations.

The effects of oral iodized oil on intelligence, thyroid status, and somatic growth in school-age children from an area of endemic goiter

One hundred goitrous school children received 475 mg iodized oil by mouth, while 100 controls received mineral oil, on a double-blind basis. On follow-up 22 months later the urinary iodine had increased and goiter size had decreased in both groups, more strikingly in the iodine-treated children. There were no consistent differences between the two treatment groups in rate of somatic growth or performance on the Stanford-Binet and Bender tests. Because of the complexities introduced by increases in urinary iodine in the controls, we compared goiter reduction with improvement in IQ score in all children, regardless of group, and found a significant relationship (p = 0.014), particularly in girls (p = 0.029). We conclude that oral iodized oil is an attractive alternative to its injection but we recommend an approximate doubling of the dose used here for more effective control. Also, while our data are not conclusive, they support the possibility that correction of iodine deficiency may improve mental performance in school age children, particularly girls.

Social justice and the demographic transition: lessons from India's Kerala State

Kerala is a small, densely crowded state in South India. It is a poor state, even by Indian standards. Its per capita income of US$80 lies well below the all-India average of US$120, and it suffers from the lowest per capita caloric intake in India. Nevertheless, Kerala has managed to achieve the demographic transition from high (premodern) to low (modern) birth and death rates-something no other Indian state has been able to attain. Indeed, the magnitude of Kerala's fertility decline-the birth rate fell from 39 in 1961 to 26.5 in 1974-has never before been observed in a nation with comparable levels of income and undernutrition. Other indices of Kerala's soical development are equally surprising: levels of literacy, life expectancy, female education, and age at marriage are the highest in India, while mortality rates, including infant and child mortality, are the lowest among Indian states. But Kerala's anomalous and unexpected demographic trends and levels are not the result of the direct interventions designed to influence health and fertility levels elsewhere in India-conventional strategies of population control and health services delivery that thus far are notable for their failure to generate such positive results. Instead, Kerala's demographic levels evidently reflect a broad social response to structural reforms in its political economy.

Paradigms in migration research: exploring "moorings" as a schema

"When considering where migration research interests may proceed, this article suggests much could be gained by considering theories of human motivation which, in the field of social psychology, represents a theoretical progression from the behavioural and cognitive approaches. The article suggests that combining theories of human motivation with the developing understanding of cultural influences may provide linkages between, on the one hand, the personal realm of migration and, on the other, the regional institutional framework of politicoeconomic structure within which people make their decisions.... The focus is on the migrant who remains within the same broad cultural context (such as within the same nation or ethnic group), but travels away from the confines of the general area in which he or she previously resided. Thus a person undertaking intraurban relocation is not regarded here as a 'migrant', and the schema proposed will probably not apply to international migration."

Low sex ratios of births in areas at risk from air pollution from incinerators, as shown by geographical analysis and 3-dimensional mapping

Previous research in environmental and occupational health has suggested that fluctuations in the sex ratios of births might provide a useful early warning to the possible health effects of toxins or other stresses in the environment. To examine further this hypothesis, we investigated the sex ratios of births in an area in central Scotland which contained two incineration plants. Analyses of the sex ratios, at various levels of geographical detail and using 3-dimensional mapping techniques, in the residential areas at risk from airborne pollution from these incinerators showed locations with statistically significant excesses of female births.

Predicting contraceptive behavior from attitudes: a comparison of within- versus across-subjects procedures

Within- versus across-subjects procedures for predicting behavior from attitudes were contrasted. Each procedure requires a comparison among attitudes in order to generate a prediction; the comparison is either among the same attitudes held by different people (across subjects) or among different attitudes held by the same person (within subject). It was hypothesized that the within-subject model provides a more adequate explanation of behavior from attitudinal constructs and, hence, more accurate prediction of behavior from attitudes than does the across-subjects model. To test this view, a sample of 349 married couples was administered a questionnaire containing measures of three attitudinal components--affect, cognition, and conation--toward each of four contraceptive methods--oral contraceptives, IUD, diaphragm, and condoms. Contraceptive behavior was assessed 1 year later. In support of the hypothesis, the within-subject predictions bore a significantly stronger relation to the behavioral criteria than did the across-subjects predictions. This effect was consistent for each of the three components of attitude, for the prediction of behavior and behavioral intention, for male and female respondents, and for a variety of contraceptive behaviors. In addition, both the within- and the across-subjects analyses demonstrated a clear rank ordering in the predictive validity of the three attitudinal components: Conation was a better predictor of behavior than was affect, which, in turn, was better than cognition.

Longitudinal stability and predictability of sexual perceptions, intentions, and behaviors among early adolescent African-Americans

PURPOSE

To assess the stability and predictability of perceptions, intentions, and behaviors regarding intended sexual intercourse and condom use.

METHODS

One hundred and nineteen African-American youth aged 9-15 years living in urban public housing provided information at baseline and 6 months later using a theory-based and culturally- and developmentally-tailored instrument assessing perceptions, intentions, and sexual behaviors.

RESULTS

Over the 6-month study interval, individual behaviors, intentions, and perceptions demonstrated considerable stability. Intentions regarding sexual intercourse in the next half-year were predictive of subsequent coitus among the entire cohort and among the subset who were virgins at baseline. Youth who thought it likely that they would be sexually-active in the next 6 months were at significantly elevated risk of doing so, compared to youth who were uncertain or thought coitus unlikely. However, intentions regarding future coitus among the subset of youth who were sexually-experienced at baseline were not predictive of future coital behavior.

CONCLUSIONS

These data suggest that social cognitive behavioral models that incorporate intentions and perceptions are appropriate as the theoretical basis for interventions targeting these young adolescents.