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 289 records · Page 16Linked to original sources

PubMed2005

The Chemnitz LogAnalyzer: a tool for analyzing data from hypertext navigation research.

Computer-based studies usually produce log files as raw data. These data cannot be analyzed adequately with conventional statistical software. The Chemnitz LogAnalyzer provides tools for quick and comfortable visualization and analyses of hypertext navigation behavior by individual users and for aggregated data. In addition, it supports analogous analyses of questionnaire data and reanalysis with respect to several predefined orders of nodes of the same hypertext. As an illustration of how to use the Chemnitz LogAnalyzer, we give an account of one study on learning with hypertext. Participants either searched for specific details or read a hypertext document to familiarize themselves with its content. The tool helped identify navigation strategies affected by these two processing goals and provided comparisons, for example, of processing times and visited sites. Altogether, the Chemnitz LogAnalyzer fills the gap between log files as raw data of Web-based studies and conventional statistical software.

Adult↗

PubMed1989

[Factors of random selection in epidemiological surveys].

In epidemiological surveys the association of variable under study, for example, morbidity and conditions of work, may be distorted by phenomena of selection. The most frequent effect of selection is "the effect of healthy worker" which consists in lower morbidity and mortality of workers as compared to the population at large. This effect can mask the pathogenic action of environmental conditions. Under other circumstances multiple effects of selection, on the contrary, may additionally enhance the association between morbidity and the environmental conditions. The elimination of selection errors is possible, if the analysis of data takes into account the broad range of variables capable of affecting the dependence. The issue of causative nature of dependence should be solved proceeding from the analysis of the aggregate data on the problem.

Age Factors↗

PubMed1988

Access to kidney transplantation. Has the United States eliminated income and racial differences?

We analyzed the effect of patient and dialysis unit characteristics on access to kidney transplantation using several different approaches, including an analysis of individual patient data from a systematic random sample of 2900 new dialysis patients from each year 1981 to 1985 (14721 patients total). Additional analyses focused on the composition of transplant waiting lists and aggregate data from a 1984 census of 1133 dialysis and transplant units. White, male, young, nondiabetic, high-income patients treated in smaller units are more likely to receive a cadaver transplant under Medicare than are other kidney patients. Profit status of the dialysis unit was not found to be correlated to access to transplantation, although size of the unit may be correlated to access. Future analysis should focus on whether patient access has been inappropriately compromised. Possible factors unexplored in this analysis include differential patient preferences and medical suitability, as well as differential medical access.

Adult↗

PubMedDate not supplied

Renal registries in the era of guidelines, standards and quality improvement. One view from the UK Renal Registry experience.

Over the past decade the UK Renal Registry has rehearsed the collection, analysis and presentation of a range of laboratory, as well as demographic, data from an increasing number of renal units. This has been accomplished by fully electronic means. The normalisation of disparate laboratory results to allow comparative audit remains a problem. The exercise has allowed a largely passive and intuitive exploration of the role that such data aggregation can play in a modern clinical context that is influenced by the Evidence Based Medicine movement and the development of Clinical Practice Guidelines, Standards and Clinical Performance Measures. To extend the data collection to clinical variables from these unselected patient groups, in order to explain as well as to describe clinical activity, is attractive but appears yet more challenging. These experiences can be used perhaps by the nephrological community to inform the further development of similar proposals in Europe, especially the concepts and structures required to link such information to the prospect of real clinical benefit.

Humans↗

PubMed2000

Streptokinase in acute ischemic stroke: an individual patient data meta-analysis : The Thrombolysis in Acute Stroke Pooling Project.

BACKGROUND AND PURPOSE: Three major randomized controlled trials of streptokinase in acute ischemic stroke were curtailed because of safety concerns. The prospective Thrombolysis in Acute Stroke Pooling Project (TAS-PP) was established to examine the aggregate data to identify factors influencing the effect of streptokinase. METHODS: Individual patient data from the Australian Streptokinase Trial (ASK), Multicentre Acute Stroke Trial-Europe (MAST-E), Multicentre Acute Stroke Trial-Italy (MAST-I), and Glasgow Trial (Glasgow) were pooled. Multivariate modeling determined the interaction between treatment effect and delay from symptom onset to treatment, predicted baseline risk, age, concomitant aspirin or heparin use, and the presence of early CT signs on the outcomes of 10-day death, death and disability, or death alone at 3 or 6 months. RESULTS: Patients' records were pooled (total 1292 patients; streptokinase, n=653, no streptokinase n=639). The subgroup analysis of treatment effect according to delay from symptoms to inclusion shows only a trend toward a better treatment effect with shorter delay, which is not statistically significant for any outcome. Heavier patients in MAST-E may have had a lower (non significant) risk from the fixed dose of 1.5 million units of streptokinase. Concomitant aspirin increased the excess mortality rates in streptokinase-treated patients (17% without aspirin versus 91% with aspirin, P=0.005). The presence of early CT scan signs did not increase the detrimental effect of streptokinase. CONCLUSIONS: Few factors influenced the response to streptokinase. However, earlier administration, lower doses of streptokinase, and avoidance of concomitant aspirin should be considered if further streptokinase trials in acute stroke are planned.

Acute Disease↗

PubMed2006

A novel microfluidic device for male subfertility screening.

PURPOSE: To our knowledge no simple, disposable and accurate test of semen quality currently exists. A novel technique to assess the motile sperm concentration of the human ejaculate has been designed and its results are presented. MATERIALS AND METHODS: In a micromachined device fluorescently labeled motile sperm traverse a hydrostatic microfluid line to a target detection cuvette. A microfluorometer assesses the fluorescence signal generated by sperm accumulating there throughout a 50-minute study period. A total of 21 semen specimens from men presenting to our university based reproductive endocrinology and infertility center were tested a total of 67 times. Semen parameters determined by computer assisted semen analysis were compared to the signal reported by the microfluidic device. RESULTS: The fluorescence signal increased throughout the data collection period for all samples. Pearson r values relating the device signal to total and progressive motile concentration were 0.79 and 0.80, respectively (each p <0.001). A signal threshold based on the aggregate data were established, correlating with the WHO standard of the normal total motile sperm concentration. As a screening test, the device was 94% sensitive and 97% specific for identifying samples with less than the WHO standard for the total motile concentration, and 96% sensitive and 90% specific when considering the progressive motile concentration. CONCLUSIONS: A novel microfluidic device is presented that enables accurate assessment of the motile sperm concentration in human ejaculate compared to computer assisted semen analysis. Its size and design demonstrate the feasibility of applying laboratory on chip technology to male infertility screening.

Diagnostic Techniques, Urological↗

PubMed2000

Influence of orthopaedic clinical specialist certification on clinical outcomes.

STUDY DESIGN: Effect of clinical specialization was studied in a retrospective analysis of a commercial outcomes database. OBJECTIVE: To assess effectiveness of care as measured by changes in health status and efficiency as measured by visits, duration of treatment episode, and net revenue between patients treated by clinicians with and without orthopaedic clinical specialist certification (OCS). BACKGROUND: Clinical specialization is becoming common in physical therapy, but there are no studies to support improved efficiency or effectiveness with advanced practitioner competencies. METHODS AND MEASURES: A total of 258 adults treated in practices participating in the Focus on Therapeutic Outcomes process during 1996 comprised the data set. Seven physical therapists with OCS treated 129 patients (clinical specialist group). These patients were matched to 129 patients not treated by physical therapists with OCS (comparison group) randomly chosen from the aggregate data set. All patients completed a standardized health status questionnaire at initial evaluation and discharge. Standardized response means (SRMs) were calculated to measure change during treatment. RESULTS: Therapists with OCS were more efficient than therapists without OCS, using fewer visits (9.1 +/- 6.7 vs 11.2 +/- 7.4) for less estimated cost ($949 +/- $736 vs $1238 +/- $1227) during the same treatment duration (35.9 +/- 48.3 vs 35.4 +/- 25.6 days) and performed fewer treatment procedures. Overall, there was no difference in effectiveness as measured by change in health status, that is, unit of functional improvement per episode (0.89 +/- 1.0 SRM for clinical specialists compared with 0.88 +/- 1.0 SRM for comparison group). The OCS group had better value (unit of functional improvement per estimated dollar) and utilization (unit of functional improvement per visit) for the constructs of physical functioning (value: 1.31 +/- 2.7 vs 0.78 +/- 1.8; utilization: 1.25 +/- 2.2 vs 0.76 +/- 1.6) and role physical (value: 1.26 +/- 2.9 vs 0.44 +/- 3.5; utilization: 1.11 +/- 1.9 vs 0.51 +/- 2.3) (SRMs for OCS group vs comparison group, respectively). CONCLUSIONS: Our data support the conclusion that physical therapists with OCS are more efficient compared with clinicians without OCS. Study limitations in design, small sample size, and low number of clinicians are discussed.

Adult↗

PubMed2005

Diversity and change in suicide seasonality over 125 years.

BACKGROUND: Recent research has corroborated the notion that seasonality in suicide is more heterogeneous and less consistent than postulated by former scholars. This work investigates the smoothing out of suicide seasonality in Switzerland between the late 19th and the end of the 20th century. It includes analyses by region and by suicide method. METHODS: Monthly suicide frequencies in Switzerland are available for the period 1876-2000. Data on canton/region are available for the periods 1901-1920 and 1969-2000, and data on suicide method for the periods 1881-1920 and 1969-2000. Analyses focusing on the overall change rely on data aggregated by quinquennia. The Edwards' test and the peak-low ratio were used in univariate analyses of seasonality. Putative determinants of the peak-low ratio were examined using regression analysis with cantonal data. RESULTS: The decrease of seasonal effects in suicide applies to a period of more than 100 years in Switzerland. Big differences of seasonal effects have existed all the time with regard to specific methods and to specific regions. No seasonality was apparent in poisoning, and in Geneva and Basle City, respectively. However, the seasonal effects have been most impressive in drowning and hanging suicides, and in rural Catholic regions. In regression analysis, the decline in suicide seasonality is associated with the decline in the agricultural work force. CONCLUSIONS: The smoothing out of suicide seasonality in Switzerland has been a continuous long term process, which probably started by the end of 19th century. Seasonal effects in suicide will probably fade away in most regions of Switzerland and in most suicide methods. This process is in parallel with the disappearance of the traditional rural society.

Female↗

PubMed1997

Causal or casual? The role of causality assessment in pharmacovigilance.

As with any other study method, 'spontaneous reporting' in pharmacovigilance is a process of data acquisition, assessment, presentation and interpretation. The provision of information (i.e. of interpreted data) concerning previously unknown, or otherwise important adverse drug reactions is a major goal. The assessment of case reports in spontaneous reporting takes place in 2 steps: first the assessment of each case individually, and secondly the interpretation of the aggregated data. The latter step is only completed for a minority of case reports, such as when actions or measures are deemed necessary. Uncertainty in case reports regarding the involvement of the suspected drugs is an inherent drawback of spontaneous reporting. Standardised case-causality assessment has become a routine at pharmacovigilance centres around the world. It aims at a decrease in ambiguity of the data and plays a role in data exchange and the prevention of erroneous conclusions. A variety of systems for standardised causality assessment have been developed, ranging from short questionnaires to comprehensive algorithms. Since none of the available assessment systems has been validated (i.e. shown to consistently and reproducibly produce a fair approximation of the truth), causality assessment has only limited scientific value. Causality assessment neither eliminates nor quantifies uncertainty but, at best, categorises it in a semiquantitative way. Routine causality assessment is usually part of the first step in case assessment, and is based on a general system that is intended for all reactions and all drugs. During the subsequent phase of aggregated assessment, causality assessment is likely to be repeated and the use of a specific aetiological-diagnostic system may be more appropriate. It may be recommended to restrict case-causality assessment to selected case reports that are likely to play an active role in pharmacovigilance and to use specific systems, adapted to the reaction or problem involved. It is an inherent limitation of spontaneous reporting that, with the exception of rare proof-positive case reports, conclusive evidence cannot usually be produced. Standardised causality assessment has not really changed this situation. As a rule, confirmation of the connection between a drug and an adverse reaction requires further analytical or experimental study.

Adverse Drug Reaction Reporting Systems↗

PubMed1998

Use of generalized linear mixed models in analyzing mutant frequency data from the transgenic mouse assay.

The transgenic mouse assay is now widely used for the study of mutagenesis in diverse rodent tissues and to test chemicals for genotoxic potential. This kind of assay generally involves nested observations at several levels of sampling, e.g., animals, packaging reactions, and plates. Due to the common origin, the mutant frequency (MF) in tissues from the same animal are likely to be positively correlated, inducing extra variation relative to the common binomial variation. In this article, a generalized linear mixed model is used to analyze the overdispersed binomial data on mutant frequency from the transgenic mouse assay, with a random effect for each level of the sampling hierarchy. This is a comprehensive framework within which different sources of variation in the data can be evaluated in nested factorial experiments and treatment effects can be assessed simultaneously. It avoids the current practice of repeated testing for excess binomial variability at each level of the sampling hierarchy and aggregating data up the levels, but fits the data with one single model. Parameters associated with the fixed effects, particularly dose, and the variance components for the random effects (e.g., animals, packages, and plates) can be estimated and tested for significance. Data previously reported in the literature involving the lacl gene from the Big Blue mouse are used to illustrate the proposed method.

Animals↗

PubMed1987

Evaluating the significance of minimal brain dysfunction--results of an epidemiological study.

An epidemiological field investigation of 399 8-yr-old children was unable to support basic assumptions of the clinical MBD concept (existence of a homogeneous syndrome, specific psychopathology, evidence of increased perinatal risks). Using a multi-level case definition procedure and factor-analytic data aggregation, nearly complete independence was found among the diagnostical levels of neurophysiology, neuropsychology and specific skills. Main results were replicated after the application of several alternative models of case definition and were further confirmed by data from a clinical sample. Present findings emphasize the necessity to reconsider the concept of MBD and its practical consequences.

Attention Deficit Disorder with Hyperactivity↗

PubMed1999

Epidemiologic studies of fatal and nonfatal cardiovascular disease and ETS exposure from spousal smoking.

This article reviews the epidemiologic studies of the association of ischemic heart disease risk and environmental tobacco smoke (ETS) exposure from a spouse who smokes. Seventeen studies (nine cohort, eight case-control) comprising more than 485,000 lifelong nonsmokers and 7,345 coronary heart disease (CHD) events were included in a meta-analysis. Together, these studies include 36% more CHD events and 58% more study subjects than were available for review by the U. S. Occupational Safety and Health Administration (OSHA) in 1994. The relative risk (RR) for fatal or nonfatal coronary events among never smokers married to smokers, compared to those whose spouses did not smoke, was RR = 1.25 (95% confidence interval [95% CI], 1.17-1.33) across the combined studies. This association was statistically similar in men (RR = 1.24; 95% CI, 1.15-1.32) and women (RR = 1.23; 95% CI, 1.15-1.32); in studies of cohort (RR = 1.23; 95% CI, 1.15-1. 31) and case-control (RR = 1.47; 95% CI, 1.19-1.81) design; in the United States (RR =1.22; 95% CI, 1.13-1.30) and other countries (RR = 1.41; 95% CI, 1.21-1.65); and in studies of fatal (RR = 1.22; 95% CI, 1.14-1.30) and nonfatal (RR = 1.32; 95% CI, 1.04-1.67) heart disease. In three studies that presented data separately for nonsmokers married to current or former smokers, the association was stronger when the spouses continued to smoke (RR = 1.16, 1.06-1.28) than with former smokers (RR = 0.98; 95% CI, 0.89-1.08). The aggregate data are unlikely to be attributable to chance, publication bias, confounding, or misclassification of exposure. The evidence linking heart disease and ETS exposure from a spouse has become substantially stronger since OSHA first proposed including heart disease in its risk assessment of ETS in 1994.

Adult↗

PubMed2000

Medical research in Israel and the Israel biomedical database.

The data collected for the second edition of the Directory of Medical Research in Israel and the Israel Biomedical Database have yielded very relevant information concerning the distribution of investigators, publication activities and funding sources. The aggregate data confirm the findings of the first edition published in 1996 [2]. Those facts endorse the highly concentrated and extensive nature of medical research in the Jerusalem area, which is conducted at the Hebrew University and its affiliated hospitals. In contrast, Tel Aviv University, whose basic research staff is about two-thirds the size of the Hebrew University staff, has a more diffuse relationship with its clinical staff who are located at more than half a dozen hospitals. Ben-Gurion University in Beer Sheva and the Technion in Haifa are smaller in size, but have closer geographic contact between their clinical and basic research staff. Nonetheless, all the medical schools and affiliated hospitals have good publication and funding records. It is important to note that while some aspects of the performance at basic research institutions seem to be somewhat better than at hospitals, the records are actually quite similar despite the greater burden of clinical services at the hospitals as compared to teaching responsibilities in the basic sciences. The survey also indicates the substantial number of young investigators in the latest survey who did not appear in the first survey. While this is certainly encouraging, it is also disturbing that the funding sources are apparently decreasing at a time when young investigators are attempting to become established and the increasing burden of health care costs precludes financial assistance from hospital sources. The intensity and undoubtedly the quality of medical research in Israel remains at a level consistent with many of the more advanced western countries. This conclusion is somewhat mitigated by the fact that there is a decrease in available funding and a measurable decrease in scholarly activity at a time when a new, younger generation of investigators is just beginning to become productive. In closing, we wish to stress that the collection of data for the Biomedical Database is a continuing project and we encourage all medical researches who may not have contributed relevant information to write to the Office of the Chief Scientist or contact the office by email.

Database Management Systems↗

PubMed1992

Cancer screening behaviors among U.S. women: breast cancer, 1987-1989, and cervical cancer, 1988-1989.

Data from the Behavioral Risk Factor Surveillance System (BRFSS) were used to examine trends in breast and cervical cancer screening behaviors among U.S. women in selected states. Data reported are from the 1987, 1988, and 1989 BRFSS for breast cancer screening (mammography) and from the 1988 and 1989 BRFSS for cervical cancer screening (Papanicolaou [Pap] smear). Results are presented as either state-specific or state-aggregate data for the years noted above. State-specific analyses indicated that self-reported mammography utilization increased between 1987 and 1989. Although whites and blacks reported similar mammography utilization rates both for screening and for a current or previous breast problem, disparities were evident among women of different ages and incomes. The proportion of women who reported ever having had a Pap smear and having heard of a Pap smear were extremely high and remained fairly consistent across the 2 survey years. State-aggregate analyses, however, showed that the percentage of women who had had a Pap smear within the previous year was negatively associated with age and positively associated with income. A higher proportion of blacks than whites obtained Pap smears. These results indicate that certain segments of the population are not taking full advantage of available breast and cervical cancer screening technologies. Public health strategies, such as those outlined in the Breast and Cervical Cancer Mortality Prevention Act of 1990 (Public Law 101-354), should enhance screening opportunities for these women.

Adult↗

PubMed2005

Influence of statins on postoperative wound complications after inguinal or ventral herniorrhaphy.

The lipid-lowering agents, statins, are the most commonly prescribed class of drugs in the western world. Because of their widespread use, many patients undergo surgical procedures while on statins. Statins, in addition to cholesterol-lowering effects, also have anticoagulant, immunosuppressive, and antiproliferative properties that may affect the risk of local wound complications. This study investigated the relationship between statins and postoperative wound complications in a large cohort of patients undergoing inguinal or ventral hernia repair. Data mining was performed in the Veterans Integrated Service Network (VISN)16 Data Warehouse. This database contains clinical and demographic information about all veterans cared for at the ten VA Medical Centers that comprise the South Central VA Healthcare Network in the mid-south region of the US. Aggregate data (age, body mass index, smoking history, gender, race, history of diabetes, statin use, and postoperative wound complications) were obtained for all patients who underwent inguinal or ventral hernia repair during the period October 1, 1996-November 30, 2004. During the period of the query, 10,782 patients (10,676 male, 106 female), 1,242 (11.5%) of whom received statins, underwent herniorrhaphy. Statin use did not affect the risk of wound infection or delayed wound healing. Statin use was, however, associated with an increased rate of local postoperative bleeding complications (P=0.01). When the type of hernia, age, smoking, diabetes, and body mass index were included in a multivariate analysis, statins remained borderline significant as an independent predictor of wound hematoma/postoperative bleeding (P=0.04), odds ratio 1.6 (95% CI 1.03-2.44). Patients who undergo inguinal herniorrhaphy while on statins have an increased risk of postoperative wound hematoma/hemorrhage. Focus on additional factors that may affect the propensity to postoperative bleeding and on meticulous intraoperative hemostasis are particularly important in such patients.

Diabetes Mellitus↗

PubMed2006

Monitoring health risk behavior of Dutch adolescents and the development of health promoting policies and activities: the E-MOVO project.

This paper describes a new way of monitoring the health status of Dutch adolescents in order to stimulate the development of health policies at school and local levels and providing individual feedback using modern technology. The project is called E-MOVO that stands for Electronic Monitor and Health Education, in which seven Regional Health Authorities and the University of Maastricht collaborate. In this project, adolescents completed an electronic questionnaire via the Internet which measured topics related to demographics, school, physical health, mental health, well-being, lifestyle, criminality and leisure time activities. These data were used for feedback at three levels. On the basis of their answers, adolescents received tailored feedback on lifestyle in a personal 'E-MOVO score', including links to relevant websites or other tailored information. The aggregated data were used to provide schools and municipalities with information on the health and well-being of their adolescent population. These data were used to encourage the development of health promoting policies and activities at both levels. This project was evaluated and is now adapted to implement at a national level.

Adolescent↗

PubMed1992

Unanswered questions and new directions in research on elderly migration: economic and demographic perspectives.

The availability of data from the 1990 Census and the Retirement and Health Survey will afford researchers an unparalleled opportunity to study elderly migration from several perspectives. This article focuses on economic and demographic issues. Census data will continue to serve the role of providing small area data on flows and will permit further disaggregation of behavioral differences according to age, marital status, and household relationship. They will also permit disaggregation according to the economic status of individuals and their households which, coupled with aggregate data on places of origin and destination, will facilitate comparison between such areas. The RHS data will go a long way to investigate questions thought to lie at the heart of migration behavior of older persons, but which have been difficult or impossible to study. Central to such questions will be the availability of a migration history, which will permit research on the interaction of migration behavior with critical life-course events such as retirement and the loss of a spouse.

Aged↗

PubMed1994

Emerging standards for diabetes care from a city-wide primary care audit.

Aggregated data from Manchester practices participating in the Diabetes 2000 project were used to develop peer group standards of mean performance and of excellence. The crude prevalence of known diabetes mellitus was 1.21% of which 20.2% had Type 1 diabetes. The aggregated mean of patients who had the following examinations performed in the preceding year were: glycated haemoglobin 56.8%; weight or body mass index 67.8%; foot pulses 37.3%; ankle reflexes 31.3%; proteinuria 60%; fundoscopy 48.2%; blood pressure 81.1%; serum cholesterol or lipids 34%. The percentage of patients referred to or seen by health care professionals in the preceding year were 14.4% to diabetes specialist nurses; 22.1% to opticians or ophthalmologists; 25% to chiropodists; and 21.5% to dietitians. The best performing practices examined 79% of patients fundi in the preceding year, 84% of their foot pulses, 74% of their ankle reflexes, and gave appropriate smoking advice in 65% of cases. These standards were fed back to the participating practices so that they could compare their own performance with that of the city-wide mean, and with the best performing practices. From these data practices have then been able to set themselves realistic targets for improved performance in the following year.

Diabetes Mellitus↗