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PubMed2005

The influence of demographic factors and health-related quality of life on treatment satisfaction in patients with gastroesophageal reflux disease treated with esomeprazole.

BACKGROUND: The correlation between treatment satisfaction and demographic characteristics, symptoms, or health-related quality of life (HRQL) in patients with gastroesophageal reflux disease (GERD) is unknown. The objective of this study was to assess correlates of treatment satisfaction in patients with GERD receiving a proton pump inhibitor, esomeprazole. METHODS: Adult GERD patients (n = 217) completed demography, symptom, HRQL, and treatment satisfaction questionnaires at baseline and/or after treatment with esomeprazole 40 mg once daily for 4 weeks. We used multiple linear regressions with treatment satisfaction as the dependent variable and demographic characteristics, baseline symptoms, baseline HRQL, and change scores in HRQL as independent variables. RESULTS: Among the demographic variables only Caucasian ethnicity was positively associated with treatment satisfaction. Greater vitality assessed by the Quality of Life in Reflux and Dyspepsia (QOLRAD) and worse heartburn assessed by a four-symptom scale at baseline, were associated with greater treatment satisfaction. The greater the improvement on the QOLRAD vitality (change score), the more likely the patient is to be satisfied with the treatment. CONCLUSIONS: Ethnicity, baseline vitality, baseline heartburn severity, and change in QOLRAD vitality correlate with treatment satisfaction in patients with GERD.

Adult↗
PubMed2002

An urban epidemic--an audit of an inner city young persons' clinic.

In 1996 a young persons' clinic was set up at the Archway Sexual Health Clinic. A retrospective case note review of all attendees for 7 months in 1999 was performed to assess the demography and incidence of sexually transmitted infections (STIs) amongst attenders of the clinic. There were 567 attendances, comprising 364 individuals (331 women and 33 men). Ten per cent of attendees were less than 16 years of age, and 48% were 16-18 years. Fifty-eight per cent were from ethnic minorities. Chlamydial and gonococcal infection was identified in 21.3% and 8.4%, respectively. Thirty-five per cent of new presentations by women involved pregnancy testing, 28.6% were positive. The introduction of the clinic has been successful judged both by the amount of attendances and diseases diagnosed. Specific provision of services for this group needs to be addressed by all sexual health providers.

Adolescent↗
PubMed2002

Air pollution and daily mortality: a hypothesis concerning the role of impaired homeostasis.

We propose a hypothesis to explain the association between daily fluctuations in ambient air pollution, especially airborne particles, and death rates that can be tested in an experimental model. The association between airborne particulates and mortality has been observed internationally across cities with differing sources of pollution, climates, and demographies and has involved chiefly individuals with advanced chronic illnesses and the elderly. As these individuals lose the capacity to maintain stable, optimal internal environments (i.e., as their homeostatic capacity declines), they become increasingly vulnerable to external stress. To model homeostatic capacity for predicting this vulnerability, a variety of regulated physiologic variables may be monitored prospectively. They include the maintenance of deep body temperature and heart rate, as well as the circadian oscillations around these set-points. Examples are provided of the disruptive changes shown by these variables in inbred mice as the animals approach death. We consider briefly the implications that the hypothesis may hold for several epidemiologic issues, including the degree of prematurity of the deaths, the unlikelihood of a threshold effect, and the role that coarse, noncombustive particles may play in the association.

Adult↗
PubMed2001

The misuse of biology in demographic research on racial/ethnic differences: a reply to van den Oord and Rowe.

In an article in the August 2000 issue of Demography titled "Racial Differences in Birth Health Risk: A Quantitative Genetic Approach," van den Oord and Rowe attempted to study the genetic and environmental factors contributing to the black/white gap in infant birth weight. Their findings indicate that this difference may be explained by shared environmental influences rather than by fetal genes. Yet the authors insisted in their conclusions that a strong genetic component still must play a role in determining the racial gap in birth weight, if only through maternal effects. The incompatibility between the authors' findings and their conclusions is due largely to a weakness in their conceptualization of the relationship between race and biology. Their insistence that racial groups represent discrete genetic entities, coupled with a failure to account for interactions between biological and environmental processes, illustrates the methodological and ethical problems that threaten future interdisciplinary research on racial/ethnic disparities in health.

Biological Phenomena↗
PubMed2001

One step back in understanding racial differences in birth weight.

In recognition of the biological and social connections in demographic processes, demographers have integrated biological factors into their models of population variation. This new effort has tended to focus on the analysis of fertility and mortality. Edwin J.C.G. van den Oord and David C. Rowe's article, "Racial Differences in Birth Health Risk: A Quantitative Genetic Approach," published in the August 2000 issue of Demography, is part of this effort. These authors use race as a proxy for genetic variation, which subverts even the most positive attempts to understand the impact of genetic variation on demographic processes. The authors' statistical results restate their anachronistic theory of race using latent variables that are not open to empirical testing. Although new data increase the opportunities for the examination of the relationship between biology and demographic processes researchers must be vigilant not to commit the errors of the past by misusing race as a variable.

Causality↗
PubMed2002

A simple method for estimating age-specific rates from sequential cross sections.

I develop and demonstrate a simple formula for estimating age-specific event rates for a period from "before" and "after" cross sections. The general approach applies to a wide range of estimation problems in demography, the social sciences, and epidemiology. The method arises from the formal mathematics of unstable populations and is similar in spirit to "variable-r" methods. Unlike those methods, however, the new technique does not require specialized computer programming or iterative calculations, and event rates can be calculated directly from cross-sectional data in simple spreadsheets. The article includes a formal mathematical exposition of the method, simulation tests, and several examples.

Adolescent↗
PubMed2004

The heritability of breast cancer: a Bayesian correlated frailty model applied to Swedish twins data.

The aim of this study was to investigate the role of genes and environment in susceptibility to breast cancer and to give an estimate of heritability in the propensity to develop the disease. To do this we applied an interdisciplinary approach, merging models developed in the field of demography and survival analysis - so-called frailty models - and models coming from quantitative genetics and epidemiology, namely genetic models. In our study, the inferential problem was solved in a Bayesian framework and the numerical work was carried out using MCMC methods. We used the special information coming from twin data, particularly breast cancer data, from the Swedish Twin Register. The application of a correlated log-normal frailty model leads to a very large estimate of the population heterogeneity (sigma = 6.7), and relatively small correlations between co-twins' frailties - around 0.3 for monozygotic and 0.1 for dizygotic twins. Comparing three different genetic models (an ACE, an AE and an ADE model), we furthermore concluded that genetic effects would explain globally almost 30% of the total variability of propensity to breast cancer. Environmental effects would be predominant in determining breast cancer susceptibility and these effects would be primarily individual-specific, that is, non-shared effects. Finally, a model which includes dominance genetic effects (ADE model) is preferred for genetic and statistical reasons.

Bayes Theorem↗
PubMed2004

On the meaning and existence of an effective population size.

We investigate conditions under which a model with stochastic demography or population structure converges to the coalescent with a linear change in timescale. We argue that this is a necessary condition for the existence of a meaningful effective population size. We find that such a linear timescale change is obtained when demographic fluctuations and coalescence events occur on different timescales. Simple models of population structure and randomly fluctuating population size are used to exemplify the ideas and provide an intuitive feel for the meaning of the conditions.

Computer Simulation↗
PubMed2005

Effective size of a fluctuating age-structured population.

Previous theories on the effective size of age-structured populations assumed a constant environment and, usually, a constant population size and age structure. We derive formulas for the variance effective size of populations subject to fluctuations in age structure and total population size produced by a combination of demographic and environmental stochasticity. Haploid and monoecious or dioecious diploid populations are analyzed. Recent results from stochastic demography are employed to derive a two-dimensional diffusion approximation for the joint dynamics of the total population size, N, and the frequency of a selectively neutral allele, p. The infinitesimal variance for p, multiplied by the generation time, yields an expression for the effective population size per generation. This depends on the current value of N, the generation time, demographic stochasticity, and genetic stochasticity due to Mendelian segregation, but is independent of environmental stochasticity. A formula for the effective population size over longer time intervals incorporates deterministic growth and environmental stochasticity to account for changes in N.

Age Factors↗
PubMed2006

Selection, recombination and demographic history in Drosophila miranda.

Selection, recombination, and the demographic history of a species can all have profound effects on genomewide patterns of variability. To assess the impact of these forces in the genome of Drosophila miranda, we examine polymorphism and divergence patterns at 62 loci scattered across the genome. In accordance with recent findings in D. melanogaster, we find that noncoding DNA generally evolves more slowly than synonymous sites, that the distribution of polymorphism frequencies in noncoding DNA is significantly skewed toward rare variants relative to synonymous sites, and that long introns evolve significantly slower than short introns or synonymous sites. These observations suggest that most noncoding DNA is functionally constrained and evolving under purifying selection. However, in contrast to findings in the D. melanogaster species group, we find little evidence of adaptive evolution acting on either coding or noncoding sequences in D. miranda. Levels of linkage disequilibrium (LD) in D. miranda are comparable to those observed in D. melanogaster, but vary considerably among chromosomes. These patterns suggest a significantly lower rate of recombination on autosomes, possibly due to the presence of polymorphic autosomal inversions and/or differences in chromosome sizes. All chromosomes show significant departures from the standard neutral model, including too much heterogeneity in synonymous site polymorphism relative to divergence among loci and a general excess of rare synonymous polymorphisms. These departures from neutral equilibrium expectations are discussed in the context of nonequilibrium models of demography and selection.

Animals↗
PubMed2006

Controlling the false-positive rate in multilocus genome scans for selection.

Rapid typing of genetic variation at many regions of the genome is an efficient way to survey variability in natural populations in an effort to identify segments of the genome that have experienced recent natural selection. Following such a genome scan, individual regions may be chosen for further sequencing and a more detailed analysis of patterns of variability, often to perform a parametric test for selection and to estimate the strength of a recent selective sweep. We show here that not accounting for the ascertainment of loci in such analyses leads to false inference of natural selection when the true model is selective neutrality, because the procedure of choosing unusual loci (in comparison to the rest of the genome-scan data) selects regions of the genome with genealogies similar to those expected under models of recent directional selection. We describe a simple and efficient correction for this ascertainment bias, which restores the false-positive rate to near-nominal levels. For the parameters considered here, we find that obtaining a test with the expected distribution of P-values depends on accurately accounting both for ascertainment of regions and for demography. Finally, we use simulations to explore the utility of relying on outlier loci to detect recent selective sweeps. We find that measures of diversity and of population differentiation are more effective than summaries of the site-frequency spectrum and that sequencing larger regions (2.5 kbp) in genome-scan studies leads to more power to detect recent selective sweeps.

Demography↗
PubMed2003

Monkeys and toads define areas of endemism on Sulawesi.

Ecological or geological phenomena can impose limits on geographic diversification that cause biogeographical patterns of distantly related but sympatrically occurring taxa to be similar. Concordant patterns of diversity facilitate conservation management because strategic designation of protected areas can capture complementary rather than redundant components of variation. Here we demonstrate that on the biodiverse Indonesian island of Sulawesi, seemingly idiosyncratic distributions of diversity in endemic monkeys (Macaca species) and toads (Bufo celebensis) are actually virtually identical on a fine geographic scale. It appears that range fragmentation has generated seven multi-taxon areas of genetic endemism, each of which should be targeted for conservation. Joint consideration of molecular phylogeography, morphology, and demography helps resolve apparent contradictions in paraphyletic macaque mitochondrial DNA and in undifferentiated toad morphology, and facilitates an understanding of biogeography and conservation genetics of Sulawesi fauna.

Animals↗
PubMed2003

Rainforest composition and histories of human disturbance in Solomon Islands.

On the basis of a Solomon Islands case study, we report that tropical rainforests hitherto perceived as untouched, pristine, virgin, etc., are actually sites of former settlement, extensive forest clearance, and irrigated/swidden agriculture. An unusually wide range of sources--rainforest ecology, forest classification and mapping, ethnobotany, land-use history, oral traditions, ethnographic and archaeological observations--supports our conclusions. These observations have bearings for contemporary perspectives on scenarios for rainforest regeneration after logging. They also force a revision of certain assumptions concerning Melanesian prehistory and historical demography, and indicate that interdisciplinary links between botany, archaeology and social anthropology are needed to achieve a better appreciation of rainforest dynamics.

Anthropology, Cultural↗
PubMed2003

[Estimates from a complex survey].

OBJECTIVE: To evaluate the impact of sampling design and the effect of weighting on data from the 1996 Brazilian National Survey on Demography and Health. METHODS: Secondary data analysis was performed using a sample of 1,355 interviewed women of the state of São Paulo. The sampling design of the National Survey of Household Sampling (PNAD) was used as a reference, and the municipality as primary sampling unit. The ratio estimator and Taylor's approximation for variance were calculated using the primary sampling units and several modalities of weighting. The indicators used to evaluate precision and validity were confidence intervals, design effects (Deff) and biases. RESULTS: For the four procedures, the differences between upper and lower point estimates for prevalence were not greater than 10%. The differences on ranges of confidence intervals were less than 20%. Use of condom and hormone injection were the variables that showed design effects greater than 1.5 and biases greater than 0.20. CONCLUSIONS: According to the results, it could be said that the cluster sampling had an impact on the precision of the estimates for two out of six variables. The impact of weighting was not significant.

Bias↗
PubMed1986

Passage to Methuselah: some demographic consequences of continued progress against mortality.

How will progress against mortality affect the size and age composition of the United States population over the next century? To gain some insight into this question, three scenarios are examined: no future progress against mortality; steady reductions in mortality at all ages at a rate of 2 per cent per year; and a radical breakthrough in the year 2000 that cuts mortality in half. All three scenarios substantially shift the composition of the US population toward older ages, steady progress resulting in the most radical change. If mortality is reduced 2 per cent per year, by 2080 almost two-fifths of the population would be above age 65 and the number of centenarians would approach 19 million. The social, economic, and public health consequences of this new demography, although speculative and uncertain, are so important that detailed analysis and planning are warranted.

Adult↗
PubMed1989

Current medical, legal and demographic perspectives on artificial reproduction in Czechoslovakia.

This paper examines artificial reproduction (AR) within a broad comparative perspective and with specific reference to Czechoslovak law, medicine, and demography. It proceeds form an analysis of the social context that gives rise to technologies of AR to a review of the two principal technologies, artificial insemination (AI) and in vitro fertilization (IVF). A final section briefly discusses some of the implications of AR for new judicial conceptions of motherhood and fatherhood.

Czechoslovakia↗
PubMedDate not supplied

Quality of travel health advice in higher-education establishments in the United Kingdom and its relationship to the demographic background of the provider.

BACKGROUND: The number of international trips undertaken by residents of the United Kingdom has risen dramatically over the past 50 years. Likewise, the numbers studying in higher education have also shown a huge increase. This study aimed to assess the appropriateness of advice given to traveling students by higher education-based health services and to relate this to the demography and experience of the professionals involved. METHODS: A postal questionnaire describing three hypothetical groups of students traveling to different parts of the world was sent to 335 doctors and nurses. These clinicians belonged to the British Association of Health Services in Higher Education. They worked in 105 practices that serve higher-educational establishments in the United Kingdom. Main outcome measures included whether appropriate immunizations were advised and given correctly through the National Health Service (NHS) or privately, and whether appropriate advice was given regarding malaria, human immunodeficiency virus (HIV), and miscellaneous risks. The sources of information used to advise travelers were also asked, and the effect of demographic characteristics of the respondents on the quality of advice was investigated. RESULTS: Two hundred fifteen (64%) questionnaires were returned. The mean score for whether the correct immunizations were advised was 77%, and for whether these were given correctly through the NHS or privately was 79.6%. For malaria, HIV, and miscellaneous risks, the scores were lower at 65%, 38%, and 32%, respectively. The score for correct immunizations was significantly affected by sex, with females respondents scoring higher (p = .036). Previous training in travel medicine improved scores for immunizations (p = .034) and for the correct choice being given through the NHS or privately (p = .006). Age, hours worked, role, and size of practice had no influence on scores. Charts in the general practice free newspapers were the most popular source of information. CONCLUSIONS: Practices serving higher-education establishments usually give appropriate advice to travelers in terms of the immunizations required, whether these are available through the NHS or privately, and about reducing risks of malaria. This is not the case regarding advice pertaining to HIV and miscellaneous risks. Previous training in travel medicine seems to correlate with the giving of more appropriate advice.

Adult↗
PubMed1991

Interaction between diabetic patients, their general practitioners and a hospital diabetic clinic.

OBJECTIVE: The aim of this study was to examine the sociodemographic data of diabetic patients referred to our clinic and to correlate these with characteristics of their individual general practitioners. How these factors affect the interaction between patients, general practitioners and a hospital diabetic clinic was evaluated. DESIGN: Prospective recruitment of consecutive referrals. SETTING: The diabetic clinic of a teaching hospital located in the inner city suburbs of Sydney. PATIENTS: Two hundred and forty-six patients with diabetes (10% insulin dependent), aged 20-86 years, participating in our Shared Care Project, a randomised controlled study on various methods of following up diabetic patients. INTERVENTIONS: Data for the study were gathered by interview and questionnaire during first assessment at the clinic. MAIN OUTCOME MEASURES: Clinical and sociodemographic characteristics of patients; the location of general practitioners, their diagnostic equipment and type of practice; and the level of detail recorded in referral letters from general practitioners. RESULTS: Diabetic patients of migrant background who cannot speak English are older and have less formal education. They see their doctors more often and seek out general practitioners who speak their language, even if it means travelling longer distances. Patients referred from 24 hour medical centres are younger, more educated and have less contact with their doctors both in duration and frequency of visits when compared with patients whose general practitioners operate in conventional sole or partnership practices. Many patients have more than one general practitioner, making communication with hospitals difficult. In their referral letters, general practitioners usually concentrate on hypertension, hypercholesterolaemia and metabolic aspects of diabetes, but under-emphasise diabetic complications; they make insufficient use of measurement of the glycosylated haemoglobin level to assess diabetic control while over-using glucose tolerance testing in making the diagnosis. The referral letter often does not contain enough information to help clinical decision making. CONCLUSIONS: Demography of patients and characteristics of general practitioners are important factors which can affect their interaction with public hospitals. Bearing in mind the work load of general practitioners and the diverse nature of patients, hospitals must implement systems which make it easier for general practitioners and patients to interact with them.

Adult↗