PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “predictive modelling”

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 1,171 records · Page 65Linked to original sources
PubMed1998

Prevalence of osteoporosis and related risk factors in UK women in the seventh decade: osteoporosis case finding by clinical referral criteria or predictive model?

The objectives of the study were: to determine the prevalence of osteoporosis in women in their seventh decade; to determine the number of women who conformed to at least one of the current East Yorkshire Clinical Referral Criteria for Osteoporosis; and to determine the sensitivity and specificity of these referral criteria in the diagnosis of osteoporosis and to compare this with the receiver operating characteristic (ROC) curve of a logistic regression model incorporating variables that were significantly associated with the risk of osteoporosis. An observational study was carried out at the Centre for Metabolic Bone Disease, Hull Royal Infirmary, on women in their seventh decade from three general practices. Densitometric assessment of lumbar spine and femoral neck was carried out using dual-energy X-ray absorptiometry (DXA) and a detailed medical history taken. The main outcome measures were prevalence of osteoporosis in women in their seventh decade and efficacy of agreed clinical referral criteria at osteoporosis case finding. Of 823 Caucasian women who underwent DXA, 24% proved to have osteoporosis at hip, spine or both according to WHO criteria. A further 49% had osteopenia detected at hip, spine or both. At least one of the referral criteria was present in 47% of the women assessed. The sensitivity of the clinical referral criteria for detection of osteoporosis was 58% with a corresponding specificity of 60%. This point lies below the ROC curve (area under fitted curve, Az = 0.73) of a logistic regression model incorporating weight, age at menopause and current use of hormone replacement therapy. In conclusion, osteoporosis according to WHO criteria was found in almost 25% of women in their seventh decade. A simple logistic regression model provided a more sensitive method of osteoporosis case finding than the selective screening component of the clinical referral criteria employed in our practice.

Absorptiometry, Photon↗
PubMed2005

A predictive model for the selective accumulation of chemicals in tumor cells.

Cationic lipophilic dyes can accumulate in mitochondria, and especially in mitochondria of tumor cells. We investigated the chemical properties and the processes allowing selective uptake into tumor cells using the Fick-Nernst-Planck equation. The model simulates uptake into cytoplasm and mitochondria and is valid for neutral molecules and ions, and thus also for weak electrolytes. The differential equation system was analytically solved for the steady-state and the dynamic case. The parameterization was for a generic human cell, with a 60 mV more negative potential at the inner mitochondrial membrane of generic tumor cells. The chemical input data were the lipophilicity (log K(OW)), the acid/base dissociation constant (pK(a)) and the electric charge (z). Accumulation in mitochondria occurred for polar acids with pK(a) between 5 and 9 owing to the ion trap, and for lipophilic bases with pK(a)>11 or permanent cations owing to electrical attraction. Selective accumulation in tumor cells was found for monovalent cations or strong bases with log K(OW) of the cation between -2 and 2, with the optimum near 0. The results are in agreement with experimental results for rhodamine 123, a series of cationic triarylmethane dyes, F16 and MKT-077, an anticancer drug targeting tumor mitochondria.

Animals↗
PubMed2026

Non-linear predictive modeling and comprehensive meta-analysis of rectal temperature in Santa Inês sheep: a systematic review of thermal challenges and biometerological trends.

A systematic and bibliometric review, combined with a meta-analysis, was used to adjust an equation for estimating the physiological responses of Santa Inês sheep subjected to different thermal challenges. The systematic review compiled data on physiological responses and the thermal environment, which were then used in the meta-analysis to adjust regression models. The bibliometric analysis mapped the relationships among studies, highlighting their usefulness in interpreting research findings and biases. Addressing prior methodological critiques, the core of this study involves replacing the linear approach with a non-linear segmented regression model to accurately define the Thermal Neutral Zone (TNZ). The Segmented Regression Model was crucial, establishing the upper limit of the Thermal Neutral Zone (TNZ) at an air temperature (tair) of 34.64 °C, where trectal begins to increase abruptly. The model, while identifying a biologically significant breakpoint, exhibited a moderate Multiple R-squared of 0.3529, highlighting the high heterogeneity and methodological variability in the current Santa Inês literature. This non-linear approach offers a biologically superior tool for identifying the onset of thermal distress.

Animals↗
PubMed1986

The introduction of the variables "traffic volume," "speed" and "belt-wearing" into a predictive model of the severity of accidents.

Three stages of modelling the monthly number of accidents and deaths are possible, ranked in order of increasing complexity according to the Box-Jenkins methodology: the univariate model; the univariate model with dummy variable; the multivariate model. By means of the transformation of the number of accidents by logarithmic function, these additive types of model become multiplicative with elasticity; the latter is much easier to handle at the interpretation stage. The greatly improved analytical capacity that more complex models allow is illustrated by means of an analysis of the evolution of the monthly number of deaths in France during the period from 1970 to 1977. The stochastic components of the time series are estimated by the univariate model, the effects of the speed-limiting and belt-wearing countermeasures by the univariate model with dummy variable and the influence of speeds and belt-wearing taking account of traffic volume by the multivariate model. These models have made it possible (i) to estimate the safety gain achieved by more widespread belt-wearing and that achieved by a narrowing of the range of speeds practised, and (ii) to conclude that there is only a small influence upon safety brought about by changes in the average speeds of private cars and other vehicles of similar mass.

Accidents, Traffic↗
PubMed1988

Occult carbon monoxide poisoning: validation of a prediction model.

Headache and dizziness are early symptoms of carbon monoxide poisoning, occurring at carboxyhemoglobin levels of greater than 10 percent. Previously, it was shown that among patients presenting to an emergency department during the winter with headache or dizziness, an algorithm for obtaining carboxyhemoglobin levels on patients who used gas stoves for heating purposes or who had similarly affected cohabitants correctly identified all patients with carboxyhemoglobin levels greater than 10 percent. To test the validity of this retrospectively derived rule, 65 patients were studied who were unaware of any carbon monoxide exposure and who presented during the winter of 1986-1987 with headache or dizziness. The algorithm correctly identified three of four patients with carboxyhemoglobin levels greater than 10 percent (sensitivity = 75 percent) and correctly excluded 45 of 61 patients with lower levels (specificity = 74 percent). The presence of symptomatic cohabitants alone was an equally sensitive (75 percent) but more specific (90 percent) marker for elevated carboxyhemoglobin levels. When data from the two cohorts were combined, stepwise multiple regression identified number of cigarettes smoked daily (F = 8.66) and concurrently symptomatic cohabitants (F = 34.71) as significant predictors of the carboxyhemoglobin level. It is concluded that a retrospectively derived rule correctly identified most cases of occult carbon monoxide poisoning when applied prospectively, and that the presence of similarly affected cohabitants was the most reliable marker for a carbon monoxide-mediated illness.

Adult↗
PubMed1985

A program for logistic prediction modelling.

A computer program has been developed that can be used for analysing a binary outcome variable and a set of regressors of type interval with a logistic (i.e. nonlinear) model.

Biometry↗
PubMed1992

Host resistance assays as predictive models in styrene immunomodulation.

Three infection models namely an oncogenic virus Encephalomyocarditis (EMCV), a rodent strain of malaria, Plasmodium berghei, and a rodent hookworm parasite, Nippostrongylus brasiliensis, were used to confirm the in vivo immunotoxic potential of styrene reported in our previous communication. The altered host resistance to these challenge infections was evaluated in rodents pre-treated with 0, 0.02, 0.03 or 0.05 x LD50 dose of styrene (5 days/week) for 4 weeks. Significantly increased mortality in mice was observed at the various tested dose levels of styrene when challenged with EMCV. Similarly the results obtained in the malaria infection model indicated increased blood parasitaemia as well as significantly enhanced mortality in styrene-treated animals. Also the rejection of N. brasiliensis was also found to be significantly impaired in animals treated with a higher dose of styrene. These results indicate that the exposure of rodents to styrene can markedly impair host resistance which may have biological significance.

Adjuvants, Immunologic↗
PubMed1995

Predictive model of intersegmental mobility of lumbar spine in the sagittal plane from skin markers.

This article describes a sagittal motion model that transforms skin marker coordinates into corresponding vertebral body coordinates. Coordinate data were obtained from 45 subjects with radiopaque skin markers over the vertebral spinous processes. Data of 30 subjects were used for model development while data of the other Fifteen subjects were used for model validation. The subjects were subjected to lateral spinal radiographs in positions of neutral, flexion, and extension. The model was developed by taking the non-linear difference between lumbar spinal profile and skin profile, the L(4) skin-fold, and the difference of L(1)-S(1) skin distraction into consideration. Regression analysis shows high coefficients of determination (range, 62.43-99.86%; mean, 86.41%) in comparing the estimated position data with the actual data in all vertebral body positions. Based on the estimated coordinates, both the intersegmental joint angles and intersegmental joint mobilities were calculated. The result of this study using the non-invasive protocol and the transformation matrices demonstrated that the intersegmental sagittal motion of lumbar spine can be obtained with error ranged from 0.05 to 0.56 degrees.

Journal Article↗
PubMed1990

A predictive model for life expectancy curves.

Life expectancy curves have a characteristic ominous shape that has fascinated scientists for centuries. Medawar was the first to explain this shape, specifically the steeply rising proneness of an average individual to die as a function of age, in evolutionary terms. The idea was that the "selective value" of the individual decreases as it has triggered other individuals taking its place (and carrying its genes) into existence. We demonstrate that this idea can be turned into a quantitative model. The resulting 4-parameter function reproduces well two well-known life expectancy curves from the first half of this century. Moreover, the easily interpretable parameters (3 of the 4) seem intuitively reasonable.

Female↗
PubMed1996

Evaluation of a prediction model of cisplatin dose based on total platinum plasma concentration.

The aim of this study was to validate prospectively a model of cisplatin dose adjustment. 27 patients (63 courses) with lung cancer were treated by a 5 day continuous infusion of cisplatin and etoposide. The dose of cisplatin was adjusted in order to reach a target plasma concentration of total platinum (TP) of 2000 mu/l at the end of the infusion. The target concentration was reached with a mean bias of 2.7% and a precision of 7.8%. The results were compared with those of a population of 38 patients (97 courses) with lung cancer and treated with the same protocol of chemotherapy, but without dose adjustment. The average dose adjustment was an increase of cisplatin dose of 20.2%. This augmentation was most important during the first course, decreasing during the following courses. There was also an increase in the etoposide AUC, although its dose was not modified. Toxicity to polymorphonuclear cells was significantly increased and was linked to etoposide AUC.

Aged↗
PubMed2005

Accident prediction model for railway-highway interfaces.

Considerable past research has explored relationships between vehicle accidents and geometric design and operation of road sections, but relatively little research has examined factors that contribute to accidents at railway-highway crossings. Between 1998 and 2002 in Korea, about 95% of railway accidents occurred at highway-rail grade crossings, resulting in 402 accidents, of which about 20% resulted in fatalities. These statistics suggest that efforts to reduce crashes at these locations may significantly reduce crash costs. The objective of this paper is to examine factors associated with railroad crossing crashes. Various statistical models are used to examine the relationships between crossing accidents and features of crossings. The paper also compares accident models developed in the United States and the safety effects of crossing elements obtained using Korea data. Crashes were observed to increase with total traffic volume and average daily train volumes. The proximity of crossings to commercial areas and the distance of the train detector from crossings are associated with larger numbers of accidents, as is the time duration between the activation of warning signals and gates. The unique contributions of the paper are the application of the gamma probability model to deal with underdispersion and the insights obtained regarding railroad crossing related vehicle crashes.

Accidents↗