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PubMed2006

ZIP-code-based versus tract-based income measures as long-term risk-adjusted mortality predictors.

There is a well-established, strong association between socioeconomic position and mortality. Public health mortality analyses thus routinely consider the confounding effect of socioeconomic position when possible. Particularly in the absence of personally reported data, researchers often use area-based measures to estimate the effects of socioeconomic position. Data are limited regarding the relative merits of measures based on US Census tract versus ZIP code (postal code). ZIP-code measures have more within-unit variation but are also more easily obtained. The current study reports on 293,138 middle-aged men screened in 14 states in 1973-1975 for the Multiple Risk Factor Intervention Trial and having 25-year mortality follow-up. In risk-adjusted proportional hazards models containing either ZIP-code-based or tract-based median household income, all-cause mortality hazard ratios were 1.16 (95% confidence interval: 1.14, 1.17) per Dollars 10,000 less ZIP-code-based income and 1.15 (95% confidence interval: 1.13, 1.16) per Dollars 10,000 less tract-based income; adding either income variable to a risk-adjusted model improved model fit substantially. Both were significant independent predictors in a combined model; tract-based income was a slightly stronger mortality predictor (hazard ratios = 1.05 and 1.11 for ZIP-code-based and tract-based income, respectively). These patterns held across various causes of death, for both Blacks and non-Blacks, and with or without adjustment for ZIP-code-based income diversity or tract-based proportion below poverty.

Analysis of Variance↗
PubMed2001

Effect of the accelerating growth of communications networks on their structure.

Motivated by data on the evolution of the Internet and World Wide Web we consider scenarios of self-organization of nonlinearly growing networks into free-scale structures. We find that the accelerating growth of networks establishes their structure. For growing networks with preferential linking and increasing density of links, two scenarios are possible. In one of them, the value of the exponent gamma of the distribution of the number of incoming links is between 3/2 and 2. In the other scenario, gamma>2 and the distribution is necessarily nonstationary.

Journal Article↗
PubMedDate not supplied

Association of dental caries and blood lead levels.

CONTEXT: Experiments show that dental caries rates are higher among lead-exposed animals, but this association has not been established in humans. OBJECTIVE: To examine the relationship between blood lead levels and dental caries. DESIGN: Cross-sectional survey conducted from 1988 to 1994 that included a dental examination and venipuncture blood lead assay. SETTING AND PARTICIPANTS: A total of 24901 persons aged 2 years and older who participated in the Third National Health and Nutrition Examination Survey, which assessed the health and nutritional status of children and adults in the United States. MAIN OUTCOME MEASURES: For children aged 2 to 11 years, the sum of decayed and filled deciduous or primary surfaces; for persons aged 6 years and older, the sum of decayed and filled permanent surfaces; for those 12 years and older, the sum of decayed, missing, and filled surfaces. RESULTS: The log of blood lead level was significantly associated with the number of affected surfaces for both deciduous and permanent teeth in all age groups, even after adjusting for sociodemographic characteristics, diet, and dental care. Among children aged 5 to 17 years, a 0.24-micromol/L (5-microg/dL) change in blood lead level was associated with an elevated risk of dental caries (odds ratio, 1.8; 95% confidence interval, 1.3-2.5). Differences in blood lead level explained some of the differences in caries prevalence in different income levels and regions of the United States. We estimated the population attributable risk of lead exposure to be 13.5% and 9.6% of dental caries occurring in 5- to 17-year-olds exposed to the high and moderate levels, respectively. CONCLUSIONS: Environmental lead exposure is associated with an increased prevalence of dental caries in the US population. Findings may help explain the distribution of caries by income and region of the United States.

Adolescent↗
PubMed1995

Community care for severely disabled people on low incomes.

OBJECTIVE: To examine the volume and distribution of formal and informal care received by severely disabled adults living at home in the community on low incomes according to type of disease. DESIGN: Analysis of computerised reports from social workers which include information on disabling conditions and on the weekly hours of care at home from formal and informal sources. SUBJECTS: 1298 severely disabled people aged 16 to 98 who received financial assistance from the Independent Living Fund in 1991-2. RESULTS: Over half (733; 56.6% (53.8 to 59.2)) of the sample were completely unable to perform five or more of the basic activities of daily living. On average the whole sample received 6.8 (6.1 to 7.6) hours of care at home a week from formal sources and 64.2 (62.4 to 65.9) hours from informal sources. In seven out of 14 disease groups, less than half in each group received any formal help at home. There were large differences in the volume of formal care within groups. In most cases no significant differences were found within diagnostic groups between those receiving care at home from district health authorities or local authorities, or both, and those who received no help at home with regard to age, dependency score, and duration of disability. Weekly hours of informal care were an important determinant of who received formal help in nine out of 14 groups. CONCLUSIONS: The amount of care received at home by low income, severely disabled people from formal sources differs across and within diagnostic groups. The fact that the variation was not systematically related to age, dependency, or duration suggests that the existing distribution of community care resources needs to be examined. Weekly hours of informal care and diagnosis seem to affect the volume and type of care received. The methods by which people in need of assistance receive help merit further investigation.

Activities of Daily Living↗
PubMed1995

Gender and the transition into practice.

Since 1990, over half the enrollees in advanced education pediatric dentistry programs have been women. The higher proportion of women in pediatric dentistry should permit examination of the practice patterns of groups of men and women at similar stages in their careers. In 1991 the American Academy of Pediatric Dentistry surveyed 4,950 dentists about a variety of issues related to practice patterns and demographics, obtaining 2,362 responses. This study conducted a secondary analysis of the survey data by developing three age-matched graduation cohorts based on gender and years since graduation: 1 to 5 years, 6 to 10 years, and over 10 years. Four areas were investigated: practice patterns, practice arrangements, distribution of time, and income. The overall differences in practice patterns between males and females were statistically significant for the Early Career Group (1 to 5 years). More males were in private practice and a higher proportion of them were practice owners. More women were dental school faculty or in private practice as an employee or contractor. The differences in practice patterns for males and females were not statistically significant for the Intermediate Career Group (6 to 10 years). In the Established Career group (over 10 years), the differences were again statistically significant, with more males as practice owners and shareholders and more women in solo practices. Analysis of time distribution showed that, in the two earlier career groups, women spend about twice as much time as men in child care. These findings may help to explain why many women in the early stages of their careers might prefer the flexibility of working for someone else. When the effects of gender and employment status on income were tested, significant differences were found for the Intermediate and Established groups, with males and practice owners having higher income levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

Health and family planning services in Bangladesh: a study in inequality.

The development of health and family planning services in Bangladesh is examined in the context of the country's political economy. Inequities of power, influence, opportunity, and the ownership and distribution of assets and income are seen to lie at the root of the "Bangladesh crisis." In this, the country is not unlike many others in the Third World, only more so. The internal and external pressures which have contributed to a coercive attitude toward the problem of too rapid population growth are discussed. The allocation of Bangladeshi health service resources is examined in terms of expenditure, manpower, and facilities; they are found to be both inequitably distributed and inefficiently applied. Some alternatives to present patterns of development are touched upon. It is concluded that despite the country's poverty, most people do not have to go without basic primary health care (including family planning), which can be afforded even by countries as economically impoverished as Bangladesh.

Bangladesh↗
PubMed2004

Disposal frequencies of selected recyclable wastes in Dar es Salaam.

A statistical survey of households based upon questionnaires distributed via primary schools has been carried out in five wards of Dar es Salaam, Tanzania, to estimate disposal frequencies (number of items disposed per week) for newsprint, metal cans, glass and plastic containers and plastic shopping bags. Plastic shopping bags are disposed most frequently while glass containers are disposed least frequently. The statistical distribution of disposal frequencies, which seems to be influenced by household income, is well described by Poisson distribution. Disposal frequencies are mutually correlated at 95% level of probability despite the differences in disposal patterns of individual households.

Conservation of Natural Resources↗
PubMedDate not supplied

Prevalence and nature of allergy and chemical sensitivity in a general population.

The objectives of this study were (a) to determine the self-reported prevalence of allergy and chemical sensitivity in a rural population of eastern North Carolina, (b) to determine the type and frequency of symptoms for each condition, and (c) to determine the demographic groups affected. A random general telephone survey was conducted during the period May 14, 1993, to September 10, 1993, and questions about allergy and chemical sensitivity were asked. Of the 1 446 households contacted, 1 027 (71%) individuals agreed to participate. Allergies were reported by 365 (35%) individuals. Thirty percent of allergic individuals reported that symptoms occurred once or more each week, whereas 61% reported that symptoms occurred, at most, once each month. Allergic symptoms that occurred daily were reported by 5.3% of the total population. Chemical sensitivity was reported by 336 (33%) individuals. Thirty-five per cent of chemically sensitive individuals reported symptoms at least once each week, whereas 53% reported that symptoms occurred once (or less) each month. Symptoms of chemical sensitivity that occurred daily were reported by 3.9% of the total population. Both allergy and chemical sensitivity were distributed widely across age, income, race, and educational groups. Simultaneous allergy and chemical sensitivity were reported by 16.9% of the population, allergy without chemical sensitivity by 16.0%, chemical sensitivity without allergy by 18.2%, and neither condition by 48.9%. If the prevalence of sensitivity to chemical irritants is, in fact, equivalent to that of allergy, as was found in this study, then support for the scientific investigation of chemical sensitivity is justified.

Adolescent↗
PubMed2004

Income-related inequality in the use of dental services in Finland.

The aim of this article is to measure and explain income-related inequalities in dentist utilisation. We apply concentration and horizontal inequity indices and the decomposition method to decompose observed inequalities into sources. The data are from the Finnish Health Care Survey of 1996. We examine three measures of utilisation: (a) the total number of visits; (b) the probability of visiting a dentist; and (c) the conditional number of positive visits for (i) visits to all dentists, (ii) those to public dentists and (iii) those to private dentists. The results for the whole sample show pro-poor inequities in all three measures of utilisation in public care, whereas in the first two measures there are pro-rich inequities nationwide and in private care. Among those entitled to age-based subsidised dental care, we find equality and equity in all three measures of utilisation nationwide. The two main factors related to pro-rich distributions of use are income and dentist's recall. To enhance equity in dental care across income groups, attention should be focused on supply factors and other incentives to encourage the poor to contact dentists more often.

Adolescent↗
PubMed1996

Does women's work improve their nutrition: evidence from the urban Philippines.

Women's market work in developing countries is thought to improve their well-being directly through increased income for health-related purchases and indirectly through elevating women's status within the household. While a number of studies have looked at the effects of women's work and the cost of women's time on child nutrition and welfare, the direct effects of women's work on their own welfare have been largely untested. Using data on 1963 urban Filipino women from the Cebu Longitudinal Health and Nutrition Survey, we examined the relationship between women's work and their dietary intakes of energy, protein, fat, calcium, and iron from home and commercially prepared foods. Determinants equations for home and commercial intakes were estimated simultaneously to adjust for non-independence. Appropriate methods were used to deal with selectivity, endogeneity, and unobserved heterogeneity. Nearly half (48%) of the women worked for pay, and commercially prepared foods made up an important part of working women's diets. Not only did women's work improve the quality of their diets, but there were strong distributional implications; lower-income women gained more than higher-income women. Employment sector also influenced women's dietary patterns. Informal non-wage work was associated with increased intakes, whereas formal sector work was associated with decreased intakes. Positive effects of work in the informal sector were greater for women from low-income households. Policy implications of the dietary benefits of informal non-wage work for low-income women are discussed.

Adult↗
PubMed1989

High and low incomes in general practice.

The Review Body on Doctors' and Dentists' Remuneration deals with average incomes and costs, and little evidence is available on local variability. In a study on general practice the distribution of high and low incomes was assessed. High income practices (defined as those with net incomes per partner of more than 35,000 pounds a year) were more likely to be larger, to have younger partners, and to be located in affluent areas. Low income practices (with a net income of less than 20,000 pounds per partner) were smaller, located in more urban areas, and more likely to have Asian partners. High income practices had higher costs per patient and more staff resources. Low income practices had fewer practice resources and faced great disincentives to investment. These practices were concentrated in less affluent areas, where the need for improved organisation of practices is greatest. General practice is becoming increasingly divided between high income, high cost practices and those with low incomes and few resources.

England↗
PubMed1995

User fees and drug pricing policies: a study at Harare Central Hospital, Zimbabwe.

In 1991, Zimbabwe introduced cost recovery measures as part of its programme of economic reforms, following a course taken by many developing countries. The system of user fees in public health care, aimed to 'protect and support the vulnerable groups' by exemption or incremental fees based on 4 income brackets. Drugs were charged at a percentage of the recommended retail price in the private sector. This study of 488 outpatients at a referral hospital in Harare examined how the new fee system functioned 6 months after its introduction. Patients were interviewed and their prescription records examined. Mean charges were determined for each fee category and revenue from drug charges was analyzed in relation to purchase cost to determine the gross profit. 31% of patients were exempted from all fees upon proof of monthly earnings of less than Z$150 (Z$5 = US$1). The remainder were classified into three fee-paying categories. The mean purchase cost for drug items was Z$3.89 per outpatient prescription. Outpatients paid a mean drug charge of Z$9.75 after exemption or discount. This was 2.5 times the cost price. The number of drug items obtained differed according to fee status: the fee-exempt category received a mean of 2.9 drug items compared with 1.9 drug items in the fee-paying categories. This difference originated at the point of prescribing. A number of practical problems in fee collection were noted. The drug pricing system generated high profit even after re-distribution to low-income users. This was attributed to economical and rationalized public sector drug procurement. Observation indicated that a proportion of the vulnerable were not effectively protected due to stringent requirements for proof of income. Appraisal of the fee policy indicated the need for more effective cross-subsidy and better administrative procedures; fee revenue should be directed towards improvement in quality of service.

Cost Sharing↗
PubMed2002

From gene families and genera to incomes and internet file sizes: why power laws are so common in nature.

We present a simple explanation for the occurrence of power-law tails in statistical distributions by showing that if stochastic processes with exponential growth in expectation are killed (or observed) randomly, the distribution of the killed or observed state exhibits power-law behavior in one or both tails. This simple mechanism can explain power-law tails in the distributions of the sizes of incomes, cities, internet files, biological taxa, and in gene family and protein family frequencies.

Journal Article↗
PubMed2000

Growth and determinants of access in patient e-mail and Internet use.

OBJECTIVES: To measure the rate of access to and use of the Internet and e-mail, to determine sociodemographic predictors of access, and to measure the change in Internet and e-mail access over a 1-year interval. DESIGN: Survey study. Comparison of data with those from a similar survey from 1998. SETTING: Emergency department of a large urban pediatric teaching hospital. PARTICIPANTS: Primary caretakers of pediatric patients or the patients themselves if aged 16 years or older. MAIN OUTCOME MEASURES: Use of and access to the Internet or e-mail. RESULTS: We surveyed 214 individuals: 72.8% use or have access to the Internet, e-mail, or both, an increase from 52.2% in the 1998 survey (P<.001), and 48.5% regularly use the Internet or e-mail, compared with 43.1% in 1998 (P = .32). Outside the home, access is primarily at work (52.2%), schools (8.9%), public libraries (11.5%), and friends' and relatives' houses (16.7%). Internet use and access are linearly correlated with income (r = 0.43; P<.001). White patients are more likely to have access (odds ratio, 2.6; 95% confidence interval, 1.3-5.4; P<.001) than black or Asian patients, whereas those of Hispanic ethnicity are less likely to have access (odds ratio, 0.20; 95% confidence interval, 0.09-0.43; P<.001). However, after adjustment for race and Hispanic ethnicity, only income was a significant predictor of family access to the Internet and e-mail. CONCLUSIONS: During the past year, many patients have gained access to the Internet and e-mail, although rates of regular use have remained steady. This access is often from outside the home. Furthermore, access is directly related to income and is unevenly distributed across racial and ethnic groups.

Adolescent↗
PubMed2002

Putting equity in health back onto the social policy agenda: experience from South Africa.

Over the past decade, international health policy debates have been dominated by efficiency considerations. There has been a recent resurgence of interest in health equity, including consideration of the notions of vertical equity and procedural justice. This paper explores the possible application of these notions within the context of South Africa, a country in which inequities in income and social service distribution between 'racial' groups were systematically promoted and entrenched during four decades of minority rule, guided by apartheid and related policies. With the transition to a democratic government in 1994, equity gained prominence on the South African social policy agenda. Health equity has been awarded a particularly high priority, not least of all because the health sector is seen as vehicle for achieving rapid equity gains. In addition, many of the other equity-promoting social sector policies (such as improved access to housing and water and sanitation services) have been motivated on the basis of their potential health equity gains. The South African experience since 1994 provides useful insights into factors which may facilitate or constrain health equity progress. In particular, the constitutional entitlement to health and civil society action to maintain health equity's place on the social policy agenda are seen as important facilitating factors. Certain health sector programmes have also been developed which are intended preferentially to benefit those who have been historically dis-advantaged, and which thus support vertical equity goals. However, there have been no efforts to promote cross-subsidisation between the private and public health sectors, and initial efforts to promote coherency in social policies (through the Reconstruction and Development Programme) appear not to have been sustained. In addition, macro-economic policies (particularly the highly ambitious budget deficit reduction targets of the government) are likely to undermine some of the equity-promoting social policy initiatives. Most importantly, the potential inter-relationship of vertical equity and procedural justice goals has not been adequately recognised. As a result, and despite policy rhetoric, this paper concludes that health equity goals are critically dependent on the central involvement of the dis-advantaged in decision-making about who should receive priority, what services should be delivered and how equity-promoting initiatives should be implemented.

Civil Rights↗
PubMed2000

Infant mortality and air pollution: a comprehensive analysis of U.S. data for 1990.

This paper uses U.S. linked birth and death records to explore associations between infant mortality and environmental factors, based on spatial relationships. The analysis considers a range of infant mortality end points, regression models, and environmental and socioeconomic variables. The basic analysis involves logistic regression modeling of individuals; the cohort comprises all infants born in the United States in 1990 for whom the required data are available from the matched birth and death records. These individual data include sex, race, month of birth, and birth weight of the infant, and personal data on the mother, including age, adequacy of prenatal care, and smoking and education in most instances. Ecological variables from Census and other sources are matched on the county of usual residence and include ambient air quality, elevation above sea level, climate, number of physicians per capita, median income, racial and ethnic distribution, unemployment, and population density. The air quality variables considered were 1990 annual averages of PM10, CO, SO2, SO4(2-), and "non-sulfate PM10" (NSPM10--obtained by subtracting the estimated SO4(2-) mass from PM10). Because all variables were not available for all counties (especially maternal smoking), it was necessary to consider various subsets of the total cohort. We examined all infant deaths and deaths by age (neonatal and postneonatal), by birth weight (normal and low [< 2500 g]), and by specific causes within these categories. Special attention was given to sudden infant death syndrome (SIDS). For comparable modeling assumptions, the results for PM10 agreed with previously published estimates; however, the associations with PM10 were not specific to probable exposures or causes of death and were not robust to changes in the model and/or the locations considered. Significant negative mortality associations were found for SO4(2-). There was no indication of a role for outdoor PM2.5, but possible contributions from indoor air pollution sources cannot be ruled out, given higher SIDS rates in winter, in the north and west, and outside of large cities.

Air Pollution↗
PubMed1980

Economic incentives in health manpower policy.

Policymakers have evidenced continued concern with the issue of maldistribution of physicians among specialties and locations. Many of the recent policy proposals in this area have involved increasing the financial rewards to primary care specialization and to location of practice in underserved areas. This article examines the evidence on current economic incentives to specialize and to locate, including income and the hours of work needed to produce income. Findings suggest that current distributions of physicians among locations and specialties are more consistent with a decision to minimize hours worked, rather than an income maximization rule. Policy implications are discussed with respect to potentially perverse results which may occur if consideration is not given to this aspect of career decisions.

Health Policy↗
PubMed2002

Multiple diverse ligands binding at a single protein site: a matter of pre-existing populations.

Here, we comment on the steadily increasing body of data showing that proteins with specificity actually bind ligands of diverse shapes, sizes, and composition. Such a phenomenon is not surprising when one considers that binding is a dynamic process with populations in equilibrium and that the shape of the binding site is strongly influenced by the molecular partner. It derives implicitly from the concept of populations. All proteins, specific and nonspecific, exist in ensembles of substates. If the library of ligands in solution is large enough, favorably matching ligands with altered shapes and sizes can be expected to bind, with a redistribution of the protein populations. Point mutations at spatially distant sites may exert large conformational rearrangements and hinge effects, consistent with mutations away from the binding site leading to population shifts and (cross-)drug resistance. A similar effect is observed in protein superfamilies, in which different sequences with similar topologies display similar large-scale dynamic motions. The hinges are frequently at analogous sites, yet with different substrate specificity. Similar topologies yield similar conformational isomers, although with different distributions of population times, owing to the change in the conditions, that is, the change in the sequences. In turn, different distributions relate to binding of different sizes and shapes. Hence, the binding site shape and size are defined by the ligand. They are not independent entities of fixed proportions and cannot be analyzed independently of the binding partner. Such a proposition derives from viewing proteins as dynamic distributions, presenting to the incoming ligands a range of binding site shapes. It illustrates how presumably specific binding molecules can bind multiple ligands. In terms of drug design, the ability of a single receptor to recognize many dissimilar ligands shows the need to consider more diverse molecules. It provides a rationale for higher affinity inhibitors that are not derived from substrates at their transition states and indicates flexible docking schemes.

Binding Sites↗