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At least 217 records · Page 12Linked to original sources
PubMed2006

The inverse dose-rate effect for radon induced lung cancer: a modified approach for risk modelling.

One of the features of high LET alpha-ray exposure due to radon inhalation is the well-known inverse dose-rate effect. The longer a given dose is delivered to the lung, the higher is its carcinogenic effect. This introduces the problem of risk extrapolation from high levels of radon exposure typical for uranium miners, down to low levels of radon exposure typical for the general population. An analytical model is presented that accounts for dose-rate effects over the entire exposure range. In accordance with radiobiological considerations and microdosimetric implications, the model provides an adequate description of the inverse dose-rate effect in the higher dose range. At the same time, a linear slope at low exposures that is independent of the dose-rate of exposure is attained.

Air Pollutants, Radioactive↗
PubMed2001

Child sexual abuse, peer sexual abuse, and sexual assault in adulthood: a multi-risk model of revictimization.

This study explored the predictors and consequences of sexual assault occurring after the age of 16 years in a nonclinical sample of women. Child sexual abuse occurring before the age of 16 years was the only predictor of later sexual assault among comorbid risk factors. Peer sexual abuse, number of perpetrators, age at time of sexual abuse, and severity of sexual abuse did not increase the risk for later sexual assault. Adult sexual assault victims showed lower levels of mental health functioning than did survivors of child or peer sexual abuse. We discuss a specificity model of revictimization and the differential effects of child, peer, and adult sexual trauma on the developmental trajectory of sexual violence and psychosocial functioning.

Adolescent↗
PubMed2002

Spatial mixture relative risk models applied to disease mapping.

An important issue within health services research is the correct allocation of resources within health authority regions and the capability of public health professionals to make such allocation appropriately. This allocation is often based on a mapping of relevant disease incidence and the assessment of the geographical distribution of relative risk of disease in small areas within the health authority administrative domain. Existing methods for the statistical analysis of small area risk are mostly based on smoothing methods. However, these methods often smooth over large discontinuities in the risk surface which might be important to maintain for the purposes of resource allocation. In this paper we propose a method that involves the use of spatial mixtures of components that can provide a balance between smoothness and the maintenance of discontinuity. The method is applied to a sudden infant death incidence data set.

Epidemiologic Methods↗
PubMed2003

Modelling risk factors for injuries from dog bites in Greece: a case-only design and analysis.

We conducted a study using a newly developed dataset based on Emergency Departments records of a network of hospitals from Greece on injuries from dog bites. Our goal is three-fold: (a) to investigate if surrogate factors of leisure time are associated with increased risk of injury from bites; (b) to address recently reported contradictory results on putative association of lunar periods and injuries from dog bites; and (c) to offer a general methodology for addressing similar case-only designs with combined factors of which some can exhibit cyclical patterns. To address these goals, we used a case-only design of our dataset, and conducted an analysis where we controlled simultaneously for weekday/weekend effects, season of year (winter, spring/fall, summer), and lunar periods, because any one of these factors can contribute to the degree of exposure to injuries from dog bites. We found that increased risk of injury from bites was associated with weekends versus weekdays (RR=1.19, 95% CI: 1.10-1.29), summer versus winter (RR=1.24, 95% CI: 1.11-1.39), and fall or spring versus winter (RR=1.31, 95% CI: 1.19-1.45). The results support the hypothesis that longer leisure time at these levels of factors does increase the risk of having a bite injury. Moreover, after controlling for these factors, risk of bite injury was not associated with moon periods, thereby also helping settle a longstanding argument.

Animals↗
PubMed1995

The role of HLA antigens as indicators of disease progression in psoriatic arthritis. Multivariate relative risk model.

OBJECTIVE: To identify HLA markers for the development of severe disease in psoriatic arthritis (PsA). METHODS: Patients with PsA who were followed up prospectively over a 14-year period were included. Clinical and laboratory assessments of both active inflammation and clinical damage were performed at 6-month intervals according to a standard protocol, which also included serologic HLA typing for class I and II antigens. Progression of damage was defined as transition into higher damage states, defined by the number of damaged joints. Both univariate and multivariate models were developed to identify predictors for progression of damage. RESULTS: Univariate analysis revealed that the HLA antigens B27, B39, and DQw3 were associated with disease progression, while HLA-DR7 was "protective." The best multivariate model identified the HLA antigens B27, when DR7 was present, and DQw3, when DR7 was not present, as predicting disease progression across all transitions, while HLA-B39 was associated with progression in early disease. The addition of these HLA indicators to a model containing clinical variables resulted in a significant improvement in fit. CONCLUSION: The HLA antigens associated with PsA, B27 and B39, are risk factors for disease progression, as is the HLA class II antigen DQw3. In combination with clinical measures of disease, these HLA variables are the dominant predictors of progression.

Adolescent↗
PubMed2003

The "close-in" or ultra high-risk model: a safe and effective strategy for research and clinical intervention in prepsychotic mental disorder.

The development of a new frontier for research and early intervention in psychotic disorders is highly dependent on the construction of synergistic clinical infrastructures. This has catalyzed great progress in the recognition, enhanced treatment, and study of first episode psychosis, and the task is even more challenging when the boundaries are extended to include the earliest clinical phase of illness, the prodromal or prepsychotic phase. This article describes the conceptual and practical building blocks for the construction of service models for intervention in the postonset clinical phase prior to the attainment of current diagnostic thresholds. This is best regarded as indicated prevention, a form of very early secondary prevention, which involves a blend of immediate clinical care combined with research-oriented preventive intervention. The experience of the Personal Assessment and Crisis Evaluation (PACE) Clinic in Melbourne across several stages of growth is described and contrasted with that of several emerging centers in Europe and North America. The progress to date, the lessons learned, and the unresolved challenges and opportunities are detailed. It is concluded that service models can be developed that are acceptable and helpful to young people and their families, and that create a unique environment for the study of the transition to frank psychotic disorder. The ultimate clinical utility and general safety of this approach and the range of effective treatments remain unclear, and will be determined by more extensive research. Such research must be conducted in a logical and rigorous manner with the best designs possible, sensitive to input from consumers and caregivers and to ethical considerations.

Academies and Institutes↗
PubMed2000

[Strive for excellence and addiction to body movement: a risk model in high-level athletes].

Champion athletes strive to attain a personal goal defined by a socially constructed image of psychomotor performance to be accomplished at the moment of the championship celebration. This intrapsychic process is initiated by a transformation of the body, programmed and controlled by repeated training. The athlete's body becomes accustomed to ritualized obsessive movements, favoring the feeling of self-fulfillment solely during muscular effort (contraction/relaxation, displacement). This social goal of excellence implies personal adaptation involving an addictive link to movement: a mechanism uniquely valid in high level sports. Twelve years experience in psychological support of high-level athletes participating in Olympic sports has led to an analysis of this adaptive mechanism and a proposed psychopathological model of its invasion of the athlete's psychic economy.

Behavior, Addictive↗
PubMed2003

Risk models for chemotherapy-induced neutropenia in non-Hodgkin's lymphoma.

Non-Hodgkin's lymphoma is primarily a disease of the elderly, with 61% of the new cases reported in patients 60 years old or older. Aggressive combination chemotherapy can cure some patients, but there are frequently treatment failures and overall survival is low. Retrospective studies have found that treatment with less than standard chemotherapy doses is associated with lower survival, and surveys of practice patterns have found that many patients, especially elderly ones, are treated with substandard regimens and doses. Neutropenia is the major dose-limiting toxicity of chemotherapy in patients with non-Hodgkin's lymphoma. First-cycle use of colony-stimulating factor (CSF) can reduce the incidence of neutropenia and its complications and help maintain the chemotherapy doses. Researchers have investigated risk factors in patients with non-Hodgkin's lymphoma to determine which patients are at highest risk for neutropenia and would benefit from targeted first-cycle CSF support. It has been shown in several studies that advanced age, poor performance status, and high chemotherapy dose intensity are risk factors. Other trials suggest that low serum albumin levels, elevated lactate dehydrogenase levels, bone marrow involvement, and high levels of soluble tumor necrosis factor receptor are also risk factors. Dose intensity has also been shown in many studies to be an important predictor of survival in patients with non-Hodgkin's lymphoma. Managing the toxicity of chemotherapy with CSF has facilitated the delivery of planned dose on time, as well as dose-intensified chemotherapy regimens. The promising results from recent clinical trials of dose-dense regimens with CSF support suggest that this could prove to be the best strategy for improving patient outcomes.

Age Factors↗
PubMed1978

The use of logistic regression for modelling risk factors: with application to non-melanoma skin cancer.

Logistic regression was used to estimate the "relative" risk of basal and squamous skin cancer for such factors as cumulative lifetime solar exposure, age, complexion, and tannability. In previous reports, a subject's exposure was estimated indirectly, by latitude, or by the number of sun days in a subject's habitat. In contrast, these results are based on interview data gathered for each subject. A relatively new technique was used to estimate "relative" risk by controlling for confounding and testing for effect modification. A linear effect for the "relative" risk of cancer versus exposure was found. Tannability was shown to be a more important risk factor than complexion. This result is consistent with the work of Silverstone and Searle.

Age Factors↗
PubMed1989

Transactional risk model for short and intermediate term psychiatric inpatient treatment of children.

The transactional model provides a novel guide for the psychiatric hospital treatment of children by improving the attunement between the child and his or her important interpersonal environment. Since children's development is highly context dependent, generalization of the gains made in the hospital will largely depend upon how well the child's parents and school can internalize the hospital experience. One method to implement this transactional model is to bring the child's parents and school into the hospital to join the child's treatment team.

Child↗
PubMed1983

Predicting angiography-induced acute renal function impairment: clinical risk model.

Two hundred sixty-six patients were evaluated for development of acute renal function impairment after renal angiography. Forty-five (16.9%) had a significant increase in serum level of creatinine (sCr), six developed oliguria or anuria, and one required permanent dialysis. Age, proteinuria, abnormal baseline sCr, use of Renografin 76, and preexisting renal disease were the five independent risk factors in the series. An odds-ratio analysis establishes the relative risk (i.e., likelihood) of developing acute renal insufficiency when a given risk factor is present. For example, patients with underlying renal disease were 6.6 times more likely to develop a transient increase in sCr than those with no renal disease. A clinical test model was devised to predict the likelihood that a given individual would develop acute renal insufficiency after renal angiography on the basis of the number of risk factors present. An increasing relation was demonstrated; the more factors present, the more likely it becomes that a patient will develop acute renal insufficiency.

Acute Kidney Injury↗
PubMedDate not supplied

Relation between the tumor necrosis factor-alpha (TNF-alpha) gene and protein expression, and clinical, biochemical, and genetic markers: age, body mass index and uric acid are independent predictors for an elevated TNF-alpha plasma level in a complex risk model.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of numerous complex diseases. The plasma level of this pro-inflammatory cytokine is associated with a variety of different risk factors, but little is known about the genetic background and the complex interactions. METHODS: in this clinical study, correlations were studied between plasma levels of circulating TNF-alpha protein (ELISA), its mRNA expression in monocytes (RT-PCR) and genetic variants of TNF-alpha gene (SSCP), with several diseases, including obesity, atherosclerosis, diabetes mellitus, hypertension, as well as risk factors such as age, gender, inflammatory markers, the coagulation\fibrinolysis balance, and lipid metabolism. One hundred and ninety four clinically and biochemically well-characterized patients were enrolled. RESULTS: At the transcriptional level, measured in monocytes, no association with any clinical or biochemical parameter investigated was found, including TNF-alpha protein level. Investigating the influence of genetic variants of the TNF-alpha gene on mRNA and protein levels, only one promoter polymorphism, namely c.-238G > A, was shown to be associated with transcriptional but not with translational expression. However, at the translational level, significant positive, but weak associations were determined for obesity (P -/+ 0.037), age (P -/+ 0.038), uric acid (P < 0.001), body mass index (P -/+ 0.01), plasminogen (P -/+ 0.013), and fibrinogen (P -/+ 0.002) in bivariate regression analyses, whereas HDL-cholesterol (P -/+ 0.005) was shown to be negatively correlated. However, investigating confounding effects in stepwise multivariate regression analysis, body mass index (P -/+ 0.009), uric acid (P -/+ 0.026) and age (P -/+ 0.037) turned out to be significantly associated with plasma levels of circulating TNF-alpha (adjusted R(2) -/+ 0.117; SE: 0.688).

Adult↗
PubMed1996

Refining a risk model for occupational tuberculosis transmission.

The traditional Poisson probability model for airborne Mycobacterium tuberculosis (M.tb) infection, also termed the Wells-Riley equation, can be modified to account for a health care worker's use of respiratory protection. It was previously shown that the beta distribution on the interval [0,1] is a good descriptor of respirator penetration values experienced by an individual worker from wearing to wearing, and of average respirator penetration values experienced by different workers. Based on the premise that the gamma distribution can reasonably describe the time-varying M.tb aerosol exposure levels experienced by health care workers, analytical solutions are presented for an individual worker's cumulative risk of infection, and for the worker population mean cumulative risk of infection, with and without use of respiratory protection. The gamma distribution is shown to be similar to the lognormal in describing right-skewed distributions of aerosol exposure concentrations on the interval [0, infinity).

Humans↗
PubMed2006

Family and cognitive factors: modeling risk for aggression in children with ADHD.

OBJECTIVE: To explore the relationships of family and cognitive factors to aggression as reported by parents and teachers. METHOD: Data regarding different types of aggressive behavior were collected from parents and teachers of 165 school-age (7-11 years old) children referred to a study of attention-deficit/hyperactivity disorder and disruptive behavior. Structural equation modeling was used to examine the differential relationships of family and cognitive factors to aggression in the home and school settings. RESULTS: Family risk factors influenced aggression reported at home and at school, whereas cognitive risk factors may exert their influence on aggression at school. Significant covariance between parent and teacher report of aggressive behavior was observed. CONCLUSIONS: Intervention at the family level may serve to reduce aggressive behaviors in both home and school environments.

Aggression↗
PubMedDate not supplied

The determinants of IUD discontinuation in China: a discrete-time competing risk model analysis.

This research examines the social, demographic, and family-planning-program factors that influence the occurrence of IUD discontinuation among Chinese women, using a sample of 14,639 IUD use segments from the 1988 Chinese National Survey of Fertility and Contraceptive Prevalence. A discrete-time competing-risk event history method is employed to identify the determinants of IUD discontinuation by five kinds of reasons: contraceptive failure, expulsion, switching method, side-effects and other nonmethod-related reasons. The predictors of IUD discontinuation suggest that a number of mechanisms are in operation. Some of the determinants may reflect the effects of the family planning program; some may illustrate women's physiological and biological reactions to IUD's; some may be related to women's previous history of contraceptive use; and still others may indicate social characteristics of women that lead them to have their IUD's removed.

Adult↗