SEARCH · PubMed Health

Results for “Dynamic risk”

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 217 records · Page 12Linked to original sources

PubMed2006

Mapping of risk prone areas of kala-azar (Visceral leishmaniasis) in parts of Bihar State, India: an RS and GIS approach.

BACKGROUND & OBJECTIVES: The kala-azar fever (Visceral leishmaniasis) is continuing unabated in India for over a century, now being largely confined to the eastern part of India mainly in Bihar state and to some extent in its bordering states like West Bengal and Uttar Pradesh. Two study sites namely Patepur block in Vaishali district with high endemicity in northern part and Lohardagga block in Lohardagga district with absolute non-endemicity in southern part of Bihar were selected for the study with the following objectives : (i) to study the macro-ecosystem in relation to distribution of vector -Phlebotomus argentipes; (ii) to identify/map the risk prone areas or villages in a block for quick remedial measures; and (iii) to make use of satellite remote sensing and GIS to demonstrate the utility for rapid assessment of landuse/landcover and their relation with the incidence of kalaazar leading to the mapping of risk prone areas. METHODS: Indian Remote Sensing (IRS)-1D LISS III satellite data for the periods of March and November 2000 were analysed in Silicon graphic image processing system using ERDAS software. False color composites (FCC) were generated and landuse/landcover was assessed using Maximum likelihood supervised classification techniques based on ground truth training sets. During the study the GIS functions are used to quantify the remotely sensed landscape proportions of 5 km2 buffer surrounding each known group of villages of high occurrence of sandflies in endemic and nonendemic study sites. Instead of traditional ground based survey methods to vector surveillance, the present study used a combination of remote sensing (RS) and geographical information system (GIS) approach to develop landscape predictors of sandfly abundance-an indicator of human vector contact and as a measure of risk prone areas. RESULTS: Statistical analysis using the remotely sensed landscape variables showed that rural villages surrounded by higher proportion of transitional swamps with soft stemmed edible plants and banana, sugarcane plantations had higher sandfly abundance and would, therefore, be at higher risk prone areas for man-vector contact. INTERPRETATION & CONCLUSION: The present study clearly brought out the usefulness of satellite remote sensing technology in generating the crucial information on spatial distribution of landuse/landcover classes with special emphasis on indicator landcover classes thereby helping in prioritising the area to identify risk prone areas of kala-azar through GIS application tools.

Animals↗

PubMed2001

Ixodid ticks on white-tailed deer and feral swine in Florida.

A state-wide survey was conducted in Florida during the 1997-99 hunting seasons to examine white-tailed deer (Odocoileus virginianus) and feral swine (Sus scrofa) for potential indigenous vectors of the rickettsial agent of heartwater, Cowdria ruminantium. A total of 504 white-tailed deer and 166 feral swine was examined from 30 wildlife management areas across the state. Amblyomma maculatum, an experimental vector of C. ruminantium, was common on both deer and feral swine throughout the state. Of the collection of 3,169 ticks, 34.5% were Ixodes scapularis Say, 34.0% Amblyomma americanum (L.), 25.5% Amblyomma maculatum Koch, 5.8% Dermacentor variabilis (Say), 0.4% Ixodes affinis Neumann, 0.03% Rhipicephalus sanguineus (Latreille) and 0.01% Amblyomma auricularium (Conil). The only exotic tick collected was A. auricularium, which is found on armadillos in Central and South America and is not known to be associated with any disease. Overall, the most prevalent species on deer were I. scapularis (51.1%) and A. maculatum (35.8%), with A. americanum less prevalent (16.0%) and D. variabilis (3.0%) and I. affinis (1.9%) rare. On feral swine, the most prevalent species were I. scapularis (69.7%) and D. variabilis (56.9%), with A. maculatum (16.2%) and A. americanum (4.6%) less common. The geographic distribution of ticks differed significantly throughout the state. Both A. maculatum and Dermacentor variabilis were more prevalent on deer from southern Florida compared to northern and central Florida. In contrast, A. americanum were more prevalent in northern and central Florida but rare in southern Florida, and I. scapularis were more common in southern compared to northern Florida. These geographic differences may reflect differences in the risk of tick-borne diseases to domestic animals, wildlife and humans within Florida.

Animals↗

PubMed1992

The circadian rhythm of the perinatal mortality rate in Switzerland.

The authors examine the relation between the perinatal mortality rate (PMR), birth weight in four categories, and hour of birth throughout the week in Switzerland, using data on 672,013 births and 5,764 perinatal deaths recorded between 1979 and 1987. From Monday to Friday, the PMR follows a circadian rhythm with a regular increase from early morning to evening, with a peak for babies born between 7 and 8 p.m. This pattern of variation has two main components: The circadian rhythms for the proportion of births in the four weight categories and the PMR circadian rhythm for babies weighing more than 2.5 kg. According to a cosinor model, which describes about 40% of the total variation in the PMR, the most important determinants are changes in the proportions of births: Low birth weight increases toward the afternoon and night. Mechanisms underlying the weight-specific timing of birth are discussed, including time selection of birth according to obstetric risks, the direct effect of neonatal and obstetric care, and chronobiologic behavior.

Birth Weight↗

PubMed2005

Genetic diversity of invasive species in the Great Lakes versus their Eurasian source populations: insights for risk analysis.

Combining DNA variation data and risk assessment procedures offers important diagnostic and monitoring tools for evaluating the relative success of exotic species invasions. Risk assessment may allow us to understand how the numbers of founding individuals, genetic variants, population sources, and introduction events affect successful establishment and spread. This is particularly important in habitats that are "hotbeds" for invasive species--such as the North American Great Lakes. This study compares genetic variability and its application to risk assessment within and among three Eurasian groups and five species that successfully invaded the Great Lakes during the mid 1980s through early 1990s; including zebra and quagga mussels, round and tubenose gobies, and the ruffe. DNA sequences are compared from exotic and native populations in order to evaluate the role of genetic diversity in invasions. Close relatives are also examined, since they often invade in concert and several are saline tolerant and are likely to spread to North American estuaries. Results show that very high genetic diversity characterizes the invasions of all five species, indicating that they were founded by very large numbers of propagules and underwent no founder effects. Genetic evidence points to multiple invasion sources for both dreissenid and goby species, which appears related to especially rapid spread and widespread colonization success in a variety of habitats. In contrast, results show that the ruffe population in the Great Lakes originated from a single founding population source from the Elbe River drainage. Both the Great Lakes and the Elbe River populations of ruffe have similar genetic diversity levels--showing no founder effect, as in the other invasive species. In conclusion, high genetic variability, large numbers of founders, and multiple founding sources likely significantly contribute to the risk of an exotic species introduction's success and persistence.

Animals↗

PubMed1998

Epidemiology of dementia.

With an unprecedented demographic change in the world population, the prevention and effective treatment of age-dependent diseased has become a compelling need. Epidemiology contributes in this way by estimating the incidence and prevalence of specific categories of morbidity and by identifying the risk or protective factors of dementia. An integrative analysis of 47 surveys across 17 countries has suggested approximate rates under 1% for dementia from any cause in persons aged 60 to 69 years, rising to about 39% in persons 90 to 95 years old. The prevalence doubles with every five years of age within that range, with few differences taking into account secular changes, age, gender, place of living... Risks factors of vascular dementia are well known. Worldwide epidemiological surveys allow to differentiate "confirmed risk factors" of Alzheimer's type dementia (age, family history, Apolipoprotein E epsilon 4 genotype and Down's syndrome), "possible risk factors" (head injury, aluminum, previous depression...) and "protective factors" (education, anti-inflammatory drugs and estrogen replacement...).

Aged↗

PubMed2005

Factors associated with homelessness of adolescents under supervision of the youth protection system.

There are two factors that limit our knowledge of the risk factors associated with homelessness among runaway adolescents, namely (1) the samples used are often composed of youth homeless service users and/or youths living on the streets (visible homelessness), whereas most adolescents in fact use "private" resources (hidden homelessness), and (2) failure to use an adequate control group to identify risk factors associated specifically with homelessness. Our study compares the characteristics of two groups of youths under the supervision of the youth protection system, according to the presence or absence of periods of homelessness. The results throw light on the factors underlying the shift from "at risk" to "homeless", showing that youths with experience of homelessness are more likely to have been placed in substitute home environments, have experienced significant relationship difficulties with one of their parents (deterioration of the parent/youth relationship and parental abuse) and to have been diagnosed with behavioural disorders. The findings suggest that the decision to place young people under supervision is based more on the dynamic between risk factors rather than on the existence of behavioural problems.

Adolescent↗

PubMed1993

Risk factors for accidental poisoning in urban Malaysian children.

In a case control study, 70 children consecutively hospitalized for acute ingestion of poisons were compared with 140 other hospitalized children matched for age. Children aged less than 3 years and boys were most often the victims. Univariate analysis identified Indian race, having a parent younger than 21 years, residing at present address for less than 1 year and living in a household with more than five occupants as significant risk factors. Experience of a recent stressful event in the family barely failed to reach the level of significance. Logistic regression analysis confirmed that Indian race, having a parent younger than 21 years and residing less than 1 year at the present address were independent predictors of acute poisoning. Positive interactions were noted between Indian race and duration of residence and between parental age and duration of residence. Knowledge of risk factors and their interactions may be useful in planning preventive measures against childhood poisoning.

Age Factors↗

PubMed2005

Modelling the hierarchical structure of road crash data--application to severity analysis.

Road crashes have an unquestionably hierarchical crash-car-occupant structure. Multilevel models are used with correlated data, but their application to crash data can be difficult. The number of sub-clusters per cluster is small, with less than two cars per crash and less than two occupants per car, whereas the number of clusters can be high, with several hundred/thousand crashes. Application of the Monte-Carlo method on observed and simulated French road crash data between 1996 and 2000 allows comparing estimations produced by multilevel logistic models (MLM), Generalized Estimating Equation models (GEE) and logistic models (LM). On the strength of a bias study, MLM is the most efficient model while both GEE and LM underestimate parameters and confidence intervals. MLM is used as a marginal model and not as a random-effect model, i.e. only fixed effects are taken into account. Random effects allow adjusting risks on the hierarchical structure, conferring an interpretative advantage to MLM over GEE. Nevertheless, great care is needed for data coding and quite a high number of crashes are necessary in order to avoid problems and errors with estimates and estimate processes. On balance, MLM must be used when the number of vehicles per crash or the number of occupants per vehicle is high, when the LM results are questionable because they are not in line with the literature or finally when the p-values associated to risk measures are close to 5%. In other cases, LM remains a practical analytical tool for modelling crash data.

Accidents, Traffic↗

PubMed2004

The risk of a mosquito-borne infection in a heterogeneous environment.

A common assumption about malaria, dengue, and other mosquito-borne infections is that the two main components of the risk of human infection--the rate at which people are bitten (human biting rate) and the proportion of mosquitoes that are infectious--are positively correlated. In fact, these two risk factors are generated by different processes and may be negatively correlated across space and time in heterogeneous environments. Uneven distribution of blood-meal hosts and larval habitat creates a spatial mosaic of demograPhic sources and sinks. Moreover, mosquito populations fluctuate temporally, forced by environmental variables such as rainfall, temperature, and humidity. These sources of spatial and temporal heterogeneity in the distribution of mosquito populations generate variability in the human biting rate, in the proportion of mosquitoes that are infectious, and in the risk of human infection. To understand how heterogeneity affects the epidemiology of mosquito-borne infections, we developed a set of simple models that incorporate heterogeneity in a stepwise fashion. These models predict that the human biting rate is highest shortly after the mosquito densities peak, near breeding sites where adult mosquitoes emerge, and around the edges of areas where humans are aggregated. In contrast, the proportion of mosquitoes that are infectious reflects the age structure of mosquito populations; it peaks where old mosquitoes are found, far from mosquito breeding habitat, and when mosquito population density is declining. Finally, we show that estimates for the average risk of infection that are based on the average entomological inoculation rate are strongly biased in heterogeneous environments.

Animals↗

PubMed1998

Alcohol consumption and mortality. II. Studies of male populations.

AIMS: This is the second of a set of three papers evaluating drinking status and mortality risk. Analysis of eight general population surveys of men evaluated all-cause mortality rates by drinking pattern. DESIGN AND PARTICIPANTS: Raw data from three studies of youth and five studies of adults were evaluated. Logistic regression models controlled for confounding characteristics. Meta-analysis combined study results. MEASUREMENTS: Drinking pattern was alternatively defined by quantity, frequency and volume of drinking. Final models included drinking pattern (as well as abstinence in the youth models and long-term abstainers and former drinkers in adult models), age and other confounding variables. Models also evaluated interactions of age and, respectively, long-term abstinence and former drinking. FINDINGS: No evidence was found for the hypothesis that abstinence is associated with greater mortality risk than light drinking. In the youth samples, abstainers had a lower risk of dying than those drinking less than 15 times per month. One study of the adult samples showed a significant age by former drinker interaction; this did not alter the lack of association of former drinking with mortality risk or the homogeneity of results across studies for this finding. The most consistent finding was the association of heavy drinking with mortality among youth. Among adults, drinking 43 or more drinks per month and drinking 21 or more times per month were associated with increased mortality risk. Quantity per occasion was not significantly associated with mortality risk among adults. CONCLUSIONS: That frequent drinking was related to mortality risk, whereas heavier quantity was unrelated, is inconsistent with the belief that daily consumption of a few glasses of wine has salutary effects. Empirically, however, this pattern tends to be unusual. Findings were homogeneous across studies lending generalizability to results.

Adolescent↗

PubMed2003

Plasma cholinesterase levels of mountain plovers (Charadrius montanus) wintering in central California, USA.

Declines of over 60% in mountain plover (Charadrius montanus) populations over the past 30 years have made it a species of concern throughout its current range and a proposed species for listing under the U.S. Endangered Species Act. Wintering mountain plovers spend considerable time on freshly plowed agricultural fields where they may potentially be exposed to anticholinesterase pesticides. Because of the population status and wintering ecology of plovers, the objectives of our study were to use nondestructive methods to report baseline plasma cholinesterase (ChE) levels in free-ranging mountain plovers wintering in California, USA, and to assess whether sampled birds showed signs of ChE inhibition related to anticholinesterase chemical exposure. We compared plasma ChE activity for mountain plovers sampled from the Carrizo Plain (an area relatively free of anticholinesterase pesticide use) with similar measures for plovers from the Central Valley (where anticholinesterase pesticides are widely used). Analyses for ChE inhibition indicated that none of the plovers had been recently exposed to these chemicals. However, mean ChE levels of plovers from the Central Valley were significantly higher (32%) than levels reported for plovers from the Carrizo Plain. This result differs from our original assumption of higher exposure risk to mountain plovers in the Central Valley but does suggest that some effect is occurring in the ChE activity of mountain plovers wintering in California.

Animals↗

PubMed1997

A study of the breast cancer dynamics in North Carolina.

This work is concerned with the study of breast cancer incidence in the State of North Carolina. Methodologically, the current analysis illustrates the importance of spatiotemporal random field modelling and introduces a mode of reasoning that is based on a combination of inductive and deductive processes. The composite space/time analysis utilizes the variability characteristics of incidence and the mathematical features of the random field model to fit it to the data. The analysis is significantly general and can efficiently represent non-homogeneous and non-stationary characteristics of breast cancer variation. Incidence predictions are produced using data at the same time period as well as data from other time periods and disease registries. The random field provides a rigorous and systematic method for generating detailed maps, which offer a quantitative description of the incidence variation from place to place and from time to time, together with a measure of the accuracy of the incidence maps. Spatiotemporal mapping accounts for the geographical locations and the time instants of the incidence observations, which is not usually the case with most empirical Bayes methods. It is also more accurate than purely spatial statistics methods, and can offer valuable information about the breast cancer risk and dynamics in North Carolina. Field studies could be initialized in high-rate areas identified by the maps in an effort to uncover environmental or life-style factors that might be responsible for the high risk rates. Also, the incidence maps can help elucidate causal mechanisms, explain disease occurrences at a certain scale, and offer guidance in health management and administration.

Breast Neoplasms↗

PubMed2001

Transferable antibiotic resistance in multiresistant nosocomial Acinetobacter baumannii strains from seven clinics in the Slovak and Czech Republics.

Sixty-seven multiresistant nosocomial Acinetobacter baumannii isolates from patients hospitalized mostly in intensive care units of seven clinics in Slovak and Czech Republic were tested to determine their ability to transfer antibiotic resistance. All isolates were resistant to kanamycin, ticarcillin, cephalothin, cefotaxime, ceftazidime, aztreonam and susceptible to carbapenems, sulbactam and ampicillin/sulbactam. Sixty-five out of 67 strains transferred resistance determinants to Escherichia coli K-12 and Proteus mirabilis P-38 recipients. Analysis of selected transconjugants by an indirect selection method showed a more variable pattern of transferred resistance determinants. The clonal spread of strains transferring resistance seems to be an additional risk for occurrence of strains resistant to ceftazidime and aztreonam.

Acinetobacter↗

PubMed2006

Case-control geographic clustering for residential histories accounting for risk factors and covariates.

BACKGROUND: Methods for analyzing space-time variation in risk in case-control studies typically ignore residential mobility. We develop an approach for analyzing case-control data for mobile individuals and apply it to study bladder cancer in 11 counties in southeastern Michigan. At this time data collection is incomplete and no inferences should be drawn - we analyze these data to demonstrate the novel methods. Global, local and focused clustering of residential histories for 219 cases and 437 controls is quantified using time-dependent nearest neighbor relationships. Business address histories for 268 industries that release known or suspected bladder cancer carcinogens are analyzed. A logistic model accounting for smoking, gender, age, race and education specifies the probability of being a case, and is incorporated into the cluster randomization procedures. Sensitivity of clustering to definition of the proximity metric is assessed for 1 to 75 k nearest neighbors. RESULTS: Global clustering is partly explained by the covariates but remains statistically significant at 12 of the 14 levels of k considered. After accounting for the covariates 26 Local clusters are found in Lapeer, Ingham, Oakland and Jackson counties, with the clusters in Ingham and Oakland counties appearing in 1950 and persisting to the present. Statistically significant focused clusters are found about the business address histories of 22 industries located in Oakland (19 clusters), Ingham (2) and Jackson (1) counties. Clusters in central and southeastern Oakland County appear in the 1930's and persist to the present day. CONCLUSION: These methods provide a systematic approach for evaluating a series of increasingly realistic alternative hypotheses regarding the sources of excess risk. So long as selection of cases and controls is population-based and not geographically biased, these tools can provide insights into geographic risk factors that were not specifically assessed in the case-control study design.

Age Factors↗

PubMed2000

Application of geographic information technology in determining risk of eastern equine encephalomyelitis virus transmission.

Geographic information system (GIS) technology and remote sensing were used to identify landscape features determining risk of eastern equine encephalomyelitis virus (EEE) transmission as defined by the abundance of Culiseta melanura (the enzootic vector) and 6 putative epidemic-epizootic vectors in Massachusetts. Landsat Thematic Mapper data combined with aerial videography data were used to generate a map of landscape elements at epidemic-epizootic foci in southeastern Massachusetts. Geographic information system technology was used to determine the proportion of landscape elements surrounding 15 human and horse case sites where abundance data were collected for Culiseta melanura, Aedes canadensis, Aedes vexans, Culex salinarius, Coquillettidia perturbans, Anopheles quadrimaculatus, and Anopheles punctipennis. The relationships between vector abundance and landscape proportions were analyzed using stepwise linear regression. Stepwise regression indicated wetlands as the most important major class element, which accounted for up to 72.5% of the observed variation in the host-seeking populations of Ae. canadensis, Ae. vexans, and Cs. melanura. Moreover, stepwise linear regression demonstrated deciduous wetlands to be the specific wetland category contributing to the major class models. This approach of utilizing GIS technology and remote sensing in combination with street mapping can be employed to identify deciduous wetlands in neighborhoods at risk for EEE transmission and to plan more efficient schedules of pesticide applications targeting adults.

Animals↗

PubMed1995

Behavioral training and AIDS risk reduction: overcoming barriers to condom use.

To assess the short- and long-term effects of an AIDS-prevention workshop on undergraduates' attitudes about condom use and AIDS, 31 participants and 31 controls were studied immediately after training sessions as well as three months later. The workshop was aimed at reducing embarrassment to purchase condoms, encouraging positive attitudes about condoms, and promoting knowledge about AIDS. To help students overcome their embarrassment over condom purchases, a behavioral intervention was included allowing students to make condom purchases at nearby drug stores. Results revealed that participants reported less embarrassment over condom purchases after training sessions and that this effect became even stronger over time. Knowledge about AIDS and positive attitudes about condoms also increased immediately after the workshop, but these changes did not persist. Results suggest that AIDS prevention workshops may lead to transient changes unless a specific skill (i.e., condom purchasing) is targeted via behavioral training.

Acquired Immunodeficiency Syndrome↗

PubMed2004

Trends in the risk of accidents and injuries and their implications for models of fatigue and performance.

Models based on measures of fatigue and performance make the implicit assumption that they will be successful in predicting risk. The present paper reviews the available literature on shiftwork safety in which real measures of accidents or injuries could be pinpointed in time and in which the a priori risk appeared to be constant. Three main problems for the models emerged from this review: 1) risk was significantly higher on the afternoon shift than on the morning shift; 2) the dominant peak in risk over the course of the night shift occurred at about midnight; and 3) risk increased substantially over spans of four successive nights. It is suggested that the relationship between risk and fatigue may be non-linear, that models may have overestimated the recovery during short sleeps, and that day sleeps between night shifts may be less recuperative than normally timed night sleeps of the same length.

Accidents↗

PubMed2026

Toward real-time quantification of driving risks: a systematic review and research agenda of risk field theory.

In complex traffic systems, driving risk often evolves in a continuous and progressive manner prior to crash occurrence. How to effectively represent and analyze such latent risk states remains a central challenge in traffic safety research. In recent years, risk field-based approaches have introduced spatial and spatiotemporal continuous modeling paradigms, providing new perspectives for characterizing the distribution of traffic risk and its dynamic evolution. Motivated by the rapid growth of this research area and the lack of a systematic synthesis, this paper presents a comprehensive review of studies applying risk field theory to driving safety and traffic risk analysis. Following the PRISMA guidelines, relevant literature was collected through multi-database searches and analyzed using a combination of bibliometric analysis and qualitative review. The review systematically summarizes the theoretical foundations, modeling elements, data sources, analytical methods, and application domains of risk field-related research. Particular attention is given to studies that conceptualize traffic risk as a continuous field, complemented by a broader review of traffic risk factor literature to identify key elements and analytical dimensions involved in risk field modeling. On this basis, the paper synthesizes research progress in major application areas, including traffic safety state representation, driving behavior analysis, traffic conflict assessment, and autonomous driving and human-machine cooperative systems. Differences and commonalities among existing studies are compared in terms of modeling strategies, data support, and application scenarios. Through this systematic review, the paper clarifies the main research themes and methodological trends of risk field-based studies, providing a structured framework for understanding the evolution and application of this approach and offering methodological insights for risk perception modeling and safety-oriented decision support in intelligent transportation systems (ITS).

Humans↗