SEARCH · PubMed Health

Results for “Data Aggregation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

PubMed2000

Adrenal androgen and glucocorticoid dissociation in premenopausal rheumatoid arthritis: a significant correlate or precursor to onset?

Controlled studies of adrenal steroids in premenopausal women with rheumatoid arthritis (RA) have revealed subtle and inconsistent decreases in glucocorticosteroid (GCS) function, but prominent deficiencies of adrenal androgens (AA). Such findings have suggested that hypoandrogenicity may predispose to RA in younger women. However, recent prospective studies of serum cortisol and dehydroepiandrosterone sulfate (DHEAS) levels before (x = 12 yrs) the onset of the disease (pre-RA) offer an alternative perspective. Significant dissociation of serum cortisol and DHEAS levels was found only in the subgroup of premenopausal women who developed RA before age 50. This subgroup alone had significant deficiency in serum DHEAS levels. Aggregate data imply that the documented deficits of DHEAS (and other AA) in such young females are a correlate of relative adrenal insufficiency, and that subtle GCS dysfunction may either contribute to development of RA in such young women as well as pubertal girls or may predispose to earlier onset of disease.

Adrenal Glands↗

PubMed2005

Age-period-cohort analysis of Swiss suicide data, 1881-2000.

At the end of the 19(th) century, male suicide rates in Switzerland were as high as the respective rates in recent decades, whereas female suicide rates were distinctly lower. An age-period-cohort analysis was performed to provide more information about the gender-specific changes over the last century. Suicide mortality has been reported in Switzerland since 1876 when the standardised registration of mortality data began. The analysed data cover the period 1881-2000. The statistical analyses were based on log-linear models and data aggregated by 10-year age-intervals and 10-year period intervals. The results indicate similar age and period effects in males and females. The estimates representing age-specific risk increase steadily with age, with intermediate plateaus in the 20s and the 50s. The period-specific estimates follow the economic cycles. The birth cohort effects are stronger in males and weaker in females. In the males' estimates, there is a peak in cohorts born around 1840 and a low in cohorts born some 60-100 years later. The estimates increased again in generations born after World War II. In females, the birth cohort estimates are low in cohorts born in the first half of the 19(th) century and increase until the first half of the 20(th) century. Birth cohort effects remain an intriguing topic in epidemiology of suicide. A better understanding of birth cohort effects might open new doors to suicide prevention.

Age Distribution↗

PubMed2006

Clinical features of American versus non-American gynecologic cancer patients requesting information from a proprietary web-based decision-support program.

PURPOSE: As the Internet can potentially substantially reduce geographic barriers to the dissemination of health-related information, it would be interesting to know if non-American women with gynecologic malignancies accessing United States (US)-based cancer Web sites differ from American patients with the same illness. PATIENTS AND METHODS: Aggregate data from individuals providing personal clinical information into one of four proprietary gynecologic cancer (cervix, endometrial, newly diagnosed and recurrent ovarian cancers) decision-support programs (NexProfiler Treatment Option Tools for Cancer; NexCura Inc., Seattle WA, USA) currently embedded within approximately 100 established cancer-related Web sites were examined for differences between American versus non-American patient populations. RESULTS: In this analysis, which included >15,000 patients, American and non-American gynecologic cancer patients were remarkably similar in most clinical characteristics, including age, stage of disease at presentation, overall health, and desire to receive information regarding clinical trials. Notable differences included features suggestive of a more aggressive surgical philosophy in the US (e.g., higher percentage of American recurrent ovarian cancer patients reported they had undergone a secondary surgical procedure; greater use of radiotherapy in non-American cervical cancer patients). CONCLUSION: Despite differences in geographic location and health care delivery systems, American and non-American patients with gynecologic malignancies and with access to Internet-based cancer information exhibit few, but notable, differences in self-reported clinical characteristics.

Adult↗

PubMed1989

Disaggregate model of highway accident occurrence using survival theory.

The analysis of discrete accident data and aggregate exposure data frequently necessitates compromises that can obscure the relationship between accident occurrence and potential causal risk components. One way to overcome these difficulties is to develop a model of accident occurrence that includes accident and exposure data at a mathematically consistent disaggregate level. This paper describes the conceptual and mathematical development of such a model using principals of survival theory. The model predicts the probability of being involved in an accident at time t given that a vehicle has survived until that time. Several alternative functional forms are discussed including additive, proportional hazards and accelerated failure time models. Model estimation is discussed for the case in which both accident and nonaccident trips are included and for the case with only accident data. As formulated, the model has the distinct advantage of being able to consider accident and exposure data at a disaggregate level in an entirely consistent analytic framework. A conditional accident analysis is undertaken using truck accident data obtained from a major national carrier in the United States. Model results are interpretable and generally reasonable. Of particular interest is that segmenting accidents in several categories yields very different sets of significant parameters. Driver service hours seemed to most strongly effect accident risk: regularly scheduled drivers who take frequent trips are likely to have a reduced risk of an accident, particularly if they have a longer (greater than eight) number of hours off-duty just prior to a trip.

Accidents, Traffic↗

PubMed1978

Cervical and vaginal bacterial flora: ecologic niches in the female lower genital tract.

The bacterial flora of the cervix and vaginal vault were compared by obtaining duplicate specimens for quantitative bacteriologic studies in 14 patients electively admitted for hysterectomy. There were a total of 137 isolates from the 28 specimens, including 71 aerobes and 66 anaerobes. Aggregate data showed that the flora of the two sample sites were similar by both qualitative and quantitative analysis. However, individual comparison of paired specimens showed considerable differences in that 75 of the 137 isolates were recovered from only the cervix or vaginal vault. Additional studies showed that neither low concentrations of bacteria nor the culture techniques accounted for these differences. It is concluded that most women harbor distinctive bacterial populations in the cervix and vaginal vault.

Aerobiosis↗

PubMed1985

A computer program package for relative survival analysis.

A computer program package has been constructed for use in patient survival analyses for chronic diseases based on aggregated data. The central concept of the analyses--the relative survival rate--is the ratio of the observed survival rate of the patients to the survival rate expected in a group in the general population similar to the group of patients at the beginning of the follow-up (interval), with respect to age, sex and calendar time. This quantity is used to measure patient survival adjusted for the effect of mortality attributable to the competing risks of death without employing information on causes of death of individual patients. The package contains three alternative methods of estimating the relative survival rates, two different ways of estimating the expectation of life for the patients, and five methods of testing the relative survival patterns using information on the whole follow-up period. Conventional survival and competing risk analysis can also be performed with the package. It is hoped that the package will facilitate standardization of statistical methodology and terminology in long-term survival studies for chronic diseases.

Aged↗

PubMed1991

A nonparametric approach to analyzing large human populations.

There are many statistical techniques that require the assumption that the population being studied is normally distributed--regression analysis, multivariate analysis, time series analysis, and so on. Unfortunately, as the development of survey sampling has long acknowledged, large human populations are usually stratified into several different subpopulations. Since the boundaries between the strata are somewhat blurred, they are not independent, so the overall distribution of the population tends to be multimodal rather than normal. In this paper, a technique is developed to find these multimodal techniques using nonparametric density estimation. Its effectiveness is demonstrated by means of an example.

Analysis of Variance↗

PubMed1996

Uncertainty in estimated half-lives of PCBS in humans: impact on exposure assessment.

Estimates of the half-lives of PCBs in humans derived from successive body burden measurements are reviewed and found to vary widely whether based on congener-specific or aggregate data. Variability due to differences in physiological processes among individuals and in congener properties is to be expected, but does not appear to be a complete explanation. Very short half-lives (i.e. < 1 year) are unlikely for those congeners most frequently found in human blood because the exposures required to sustain observed body burdens are too large to be easily explained. Very long half-lives ( > 10 years) may be artifacts of confounding by ongoing exposures (a common effect at low body burdens) and are also suspect. The loss of significant quantities of PCBs from the blood of occupationally exposed persons with half-lives of 2-6 years is comparatively well documented (i.e. has been observed in studies with relatively large numbers of subjects and high initial body burdens). Therefore, very long half-lives must be limited to subsets of congeners or of populations if they occur at all. The impact of the use of fixed estimates of half-lives drawn from the tails of the observed range on the evaluation of regulatory standards is shown to be substantial.

Adipose Tissue↗

PubMed1983

Cadmium, zinc, and copper metabolism in the mottled mouse, an animal model for Menkes' kinky hair syndrome.

Studies of uptake and release of 64Cu, 109Cd, and 65Zn in suckling C57BL/6J male mice revealed kinetics and distributions that differed for each metal both within and among the organs analyzed, suggesting distinct, albeit overlapping, mechanisms for transport and binding of each metal. In mutants, there were tissue-specific increases in copper-binding capacity. In hemizygotes (Moblo/y) accumulation of 64Cu was increased in kidney, lung, and duodenum. In heterozygotes (Moblo/+), 64Cu content was increased in kidney, with a smaller increase in lung, and no change in duodenal Cu. Decreased 64Cu accumulation was seen in liver in both hemi- and heterozygotes. In contrast, 64Zn and 109Cd accumulation in organs of heterozygote mice was not significantly distinguishable from normal. In skin and connective tissues there is excessive accumulation of 64Cu in Moblo/+ and Moblo/y, no abnormality in heterozygote 65Zn accumulation, but a clear decrease in heterozygote 109Cd content. In both mutant kidney and liver, there was an aberrant subcellular distribution of 64Cu, with the major fraction of sequestered 64Cu in the cytosol. Our studies establish that in spite of the ubiquity of metallothioneins and the structural similarities of those that have been characterized, there is specificity and functional heterogeneity in metal binding among tissues. The aggregate data suggest that there are unique regulatory mechanisms for the metabolism of copper and zinc, while there exists, in part, an inverse relationship between the binding of copper and cadmium. Our data further suggest that the blotchy mutation involves a specific cytosolic copper storage or transport protein also capable of binding cadmium.

Animals↗

PubMed1991

Seasonal variation of Legionnaires' disease in Scotland.

A summer and autumn peak in incidence is a characteristic epidemiological feature of Legionnaires' disease, a fact which may help in diagnosis. Previous reports from Scotland have reported a winter peak. This study examined the seasonal variation in Legionnaires' disease in Scotland in each year and by category of diagnosis. A characteristic summer/autumn peak was seen for travel-related infection. For non-travel infection, there was an autumnal peak between 1978 and 1982 but an early winter peak between 1983 and 1986. Overall, the pattern could be described as a summer/autumn plateau reaching a peak in early winter. This pattern, seen in men and women, was clearest in the Greater Glasgow area. Nosocomial cases were clustered in the months of October, November and December. In non-travel cases the classical seasonal pattern was not observed and clinicians cannot rely upon this epidemiological feature for diagnosis. However, the relative infrequency of the disease between January and May was a consistent and potentially useful feature. Most reports on seasonal variation are based on aggregated data on travel and non-travel cases. The present observations question the hypotheses developed to explain the seasonal pattern and call for further studies.

Cross Infection↗

PubMed1992

Tax harmonization and the reduction of European smoking rates.

Amidst growing optimism that smoking in Europe can be greatly reduced by the year 2000, this paper simulates the possible impacts of European tax harmonization in the context of rising incomes. A range of price and income elasticities are chosen from econometric studies which use micro information. This is justified by the aggregation problems associated with studies in the smoking literature which use aggregate data. Using micro elasticities, the simulations reported in this paper show that the aims of fiscal harmonization are at variance with the aims of health promotion.

Costs and Cost Analysis↗

PubMed1988

Quantitative issues in health-related quality of life assessment.

The current interest in incorporating psychosocial outcomes into health care research raises a number of conceptual and methodological issues regarding the assessment of health-related quality of life. This paper offers an overview of some of the principal factors to consider in choosing or developing a quality of life measure, including: (a) the bandwidth-fidelity problem; (b) generic versus disease-specific focus; (C) level of data aggregation; (d) interview versus questionnaire; (e) question time-frame; (f) response scales; (g) psychometric properties; and (h) feasibility. While the discussion focuses on quantitative approaches to quality of life assessment, it is suggested that a mixture of quantitative and qualitative strategies may be most fruitful.

Chronic Disease↗

PubMed1995

Evaluating the effects of GP remuneration: problems and prospects.

General practice reform is occurring in a number of countries. Little is known, however, of the effects of remunerating general practitioners on the costs and outcomes of care. Valuable lessons can be learned for the scope and design of future research, however, from the existing literature on the effects of general practioner (GP) remuneration. The objectives of this paper are to highlight some of the problems and pitfalls that should be avoided in any further research on the effects of GP remuneration and to identify the main issues for future research. Eighteen studies of the effects of GP remuneration have been reviewed, with a focus on the methods used. Eight studies addressed the effect of changes in the level of remuneration, three evaluated the effect of special payments and bonuses and seven assessed the effects of different remuneration systems. Although there are often practical constraints on the choice of study design, crude 'before and after' analyses and the use of aggregate data should be avoided in favour of prospective evaluations using consultation-based data. The studies reviewed did not evaluate the effects of remuneration on patient welfare and were characterised by the omission of major confounding variables and an inability to generalise to other settings. These issues present a considerable challenge to researchers, GPs and policy makers.

Australia↗

PubMed1994

Application of cost-effectiveness methodology to the consideration of needlestick-prevention technology.

Data from the study of needlestick-prevention devices in 10 New York State hospitals enabled application of cost-effectiveness analysis techniques for determining relative benefits of various safety interventions. This article introduces to infection control practitioners several economic concepts related to cost-effectiveness methodology and provides two examples of how they may be applied for decision-making purposes. A critical aspect of the analysis described is the determination of a base cost of needlestick injury. By applying decision analysis to experience-based data aggregated from participating institutions, base expected cost of needlestick injury was determined to be $363.

Cost-Benefit Analysis↗

PubMed1988

Jakarta kampung morbidity variations: some policy implications.

Urban growth in the developing world is likely to be accompanied by health problems in crowded zones where services are not available. Geographical analyses of aggregated data may prove interesting, but reliability and utility of spatial correlations are greater when microscale data are acquired. In this study data for households in 11 Jakarta neighborhoods were collected in interviews. Malaria and diarrheal disease patterns have been correlated with environmental and socioeconomic variables at the household level. Several environmental characteristics seem to be closely associated with the incidence of malaria and diarrheal diseases.

Diarrhea↗

PubMed1990

Health and social inequities in Spain.

This article examines the relationship between health and social differences in Spain. The dominant explanatory models (medical, health system oriented and economical) have focused on health care as the main source of health. They have disregarded the role of socioeconomic variables in the genesis, development and cure of illness. In relation to the distribution of health, the variables analysed here are those of poverty, social class, sex, age, living conditions, lifestyles and some existential indicators using both official aggregated data and survey data. We conclude that Spain is a country with major economic, social and regional differences and manifests important variations in the health of its population. The evidence taken from the data presented here seems to indicate that poverty, living conditions and income play a relevant explanatory role.

Cross-Cultural Comparison↗

PubMed1991

The Amelia Stern syndrome: a diagnosis of a condition among female physicians?

Numerous studies have provided numerical portraits of some of the difficulties of women physicians at work in a field that traditionally has been the preserve of men. These studies, like much of recent feminist literature, often focus on the tension between maintaining a career and being a wife and mother. They usually provide aggregate data but fail to convey compellingly the nuances and emotions involved in the issues they address. Perri Klass's recent novel, Other Women's Children, the center point of this article, provides a case study of the thoughts and feelings attached to the issues addressed by the scientific inquiries. The book deals with the experiences of a woman pediatrician in a Boston hospital, a woman who uncertainly juggles her career and family responsibilities.

Adaptation, Psychological↗

PubMed1993

Regional inequalities of child mortality in peninsular Malaysia with special reference to the differentials between Perlis and Kuala Terengganu.

In Peninsular Malaysia child mortality rates (5q0) vary from 13 to 63 per thousand at district level. The spatial pattern is closely associated with the regional distribution of socio-economic factors. But due to multicollinearity it is difficult to isolate the influence of socio-economic variables from other variables by employing aggregated data. However, individual data collected in a case-control-study that was conducted in Perlis and Kuala Terengganu confirm the important role of socio-economic factors. So it should be possible to achieve a further reduction of child mortality by raising the income and educational level of the under-privileged groups. Apart from that, as the case of Perlis shows, the provision of family planning and preventive medical services may also contribute to lower child mortality independent from socio-economic changes. But, as the comparison with Kuala Terengganu shows, the utilization of family planning and preventive medical services is not only influenced by the accessibility to, but also by the socio-culturally determined acceptability of such services.

Case-Control Studies↗