SEARCH · Search PubMed

Results for “stratification”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

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

At least 433 records · Page 24Linked to original sources

PubMed1999

Gender and income in pharmacy: human capital and gender stratification theories revisited.

This is a case study of gender and earnings in pharmacy--a profession characterized by its rapid recruitment of female practitioners. We try to account for disparities in earnings between male and female pharmacists in Ontario with the aid of human capital theory and gender stratification theory. Data is drawn from a random sample of 463 Ontario pharmacists. We find a consistent sex gap in earnings regardless of occupational level of practitioners (i.e. owner, manager or employee) and net of such factors as hours worked, commitment to work, hours devoted to childcare, absences from the labour market, and years since graduation. Instead, the main reason why women in pharmacy earn less than males is because they remain employees throughout their careers. However, we are less successful at identifying the additional factors responsible for the depressed earnings of female practitioners. We discuss our findings in light of the claims of gender stratification and human capital theory.

Economics, Pharmaceutical↗

PubMed2004

[Stratification of volatile solid content and its dynamics in the process of co-composting].

Co-composting of sewage sludge and pig manure was conducted and it was indicated that, at the stages of temperature starting and high temperature composting, the difference of organic decomposition in the upper portion was largest among three portions of composting pile. The difference was largest in the lower part of the pile and the stratification effect of volatile solid (VS) content was formed at the stage of cooling, while it was largest in the middle and the stratification effect was still remarkable at the stage of maturity. At different stages of composting, the difference of VS content in the pile was of the order: the cooling > or = the maturity > the high temperature > the temperature starting. At each stage of composting, the difference of organic decomposition in the pile was as follows: the upper > the middle > the lower. The change of VS content met with first-order kinetics equation and decomposition rate of VS was 0.3 kg x d(-1) while average loss of VS content was 8.2% in the whole process of composting.

Animals↗

PubMed2005

Non-invasive sudden death risk stratification.

Most sudden cardiac deaths are caused by fatal ventricular arrhythmias (ventricular tachycardia [VT] and fibrillation) in patients with and without known structural heart diseases. Given the large number of patients potentially at risk for developing ventricular arrhythmias, any strategy for treating them prophylactically requires efficient and effective risk stratification. Both non-invasive and invasive testing may be used for prognostic evaluation of patients with heart diseases. The optimal way to use them in the risk stratification for sudden cardiac death will depend in part on the goals of screening. At present risk markers perform better at identifying low-risk patients who may not need an implantable cardioverter-defibrillator (ICD), because all tests have a high negative predictive accuracy. In our opinion an electrophysiological test should not be performed and an ICD should not be implanted in post-myocardial infarction patients with moderate left ventricular dysfunction (left ventricular ejection fraction 30-40%) with a preserved autonomic balance and without non-sustained VT. In MADIT II-like patients electrophysiological testing does not seem necessary and an ICD could not be implanted only in patients with a negative T-wave alternans test. Most of the data available refer to patients with ischemic cardiomyopathy but the preliminary data on T-wave alternans suggest its usefulness in patients with non-ischemic cardiomyopathy too, although a large definitive study has not yet been completed in this important population.

Baroreflex↗

PubMed2005

[Use of unlinked genetic markers to detect population stratification: a case-control multicenter study].

OBJECTIVE: To evaluate whether population stratification exists in microsatellite polymorphic sites. METHODS: Eight microsatellite markers not related to stroke, D11S1361, D19S927, D7S483, D14S990, D15S993, D1S2622, D1S2876 and D3S3560 located in different chromosomes were selected based on the GenBank database (http://www.gdb.org/). PCR assay was used to detect the alleles of these microsatellite in 294 patients of cerebral apoplexy, aged 58, and 325 sex, age and geographically-match controls in 7 cities in China. The PCR products were subjected to electrophoresis on the ABI 377 DNA sequencer and analyzed with Genescana and Genotypera software. The frequencies of these markers in these stroke patients and controls were compared by c2 test. Total 294 patients with stroke and 325 age, sex, and geographically matched controls were randomly selected from 973 case-control population. Eight loci including D11S1361, D19S927, D7S483, D14S990, D15S993, D1S2622, D1S2876 and D3S3560 were detected by fluorescence-based genotyping approach. RESULTS: Except for the alleles of D11S1361, the size, frequency, heterozygosity, and polymorphism information in the alleles of the other 7 microsatellite sites were in the range of 0.63 - 0.81 and their distribution varies in different races and populations. between Chinese and Caucasians. There were no differences in the frequencies of main alleles between the case group and control group (all P > or = 0.05). CONCLUSION: The selected seven markers are highly polymorphic and variable between human populations, and the genomic control data indicate that there is no unequal genetic admixture and stratification in the case-control cohort.

Aged↗

PubMed2005

[Risk stratification in pre-hospital management of myocardial infarction with ST elevation: value of a risk score profile].

The aims of this study were to evaluate new tools of risk stratification in an unselected population of myocardial infarction (MI), usable in a pre-hospital situation, and to compare the risk profile of these patients with those of other clinical trials or myocardial infarction registries. The risk scores of death at 30 days (TIMI score and TIMI risk index) based on data available in the context of coronary emergencies, were applied to the population base of the MI observatory of myocardial infarction in the Côte d'Or (RICO). The risk profile was expressed by the smoothed graph of frequency distribution of each score. The TIMI score applied to the RICO population had a high discriminating power (c = 0.80) for mortality whereas TIMI risk index was less powerful (c = 0.57). The risk profile of the RICO population was comparable to that of InTIME II, ASSENT 2 and the NRMI with reperfusion registry. The NRMI without reperfusion and the MAGIC studies had different profiles characterised by a shift in the graph towards high risk patients. The authors conclude that risk stratification scores, like the TIMI score, are valuable tools for early triage in the management of MI patients. The risk profiles allow comparative analysis of risk levels of populations notably with respect to other registries and also with respect to randomised clinical trials.

Aged↗

PubMed2006

The value of NT-proBNP in early risk stratification of acute coronary syndromes.

INTRODUCTION: The N-terminal portion of brain natriuretic peptide (NT-proBNP) has been identified as an indicator of prognosis in different cardiovascular diseases. Its role in risk stratification in patients with acute coronary syndromes (ACS) is still under evaluation. OBJECTIVE: We aimed to evaluate the prognostic value of NT-proBNP measured in the first 48 hours after admission due to an acute coronary syndrome. METHODS: Our study included 142 patients (aged 62.7 +/- 12.0 years, 70.4% males) admitted to a cardiology unit with an ACS. All laboratory evaluations were performed in the first 48 hours after admission. The mean follow-up was 200 days. Death from any cause or hospitalization because of a major acute cardiovascular event (whichever occurred first) was defined as the end-point. RESULTS: Cardiovascular risk factors were found in a significant proportion of our sample (hypertension in 56.3%, diabetes mellitus in 38.0%, current or previous smoking in 51.4%, dyslipidemia in 67.6%). Fifty-eight patients had left ventricular systolic dysfunction (LVSD). Serum levels of NT-proBNP were 2174 +/- 4801 pg/ml. Variables associated with event-free survival in univariate analysis were: NT-proBNP (HR 1.007, 95% CI 1.003-1.011, for each 100 pg/ml increment), serum glucose (hazard ratio [HR] 1.007, 95% CI 1.001-1.012, for each 1 mg/dl increment) and maximum cardiac troponin I (cTnI) level (HR 1.005, 95% CI 1.001-1.009, for each 1 ng/ml increment). The white blood count (WBC) was marginally associated with a poor prognosis (HR 1.152, 95% CI 0.994-1.335, for each 1000/mm3 increment). After adjustment for the above variables, age, sex, left ventricular systolic dysfunction, diabetes, coronary anatomy and coronary revascularization using a forward likelihood ratio Cox regression model, NT-proBNP remained the only variable with significant prognostic value (HR 1.007, 95% CI 1.003-1.011, for each 100 pg/ml increment). CONCLUSIONS: These data suggest that NT-proBNP is a strong clinical predictor of prognosis in acute coronary syndromes. Its early measurement should be included in the risk stratification strategy in this setting.

Acute Disease↗

PubMed2006

QT dispersion and heart rate variability in sudden death risk stratification in patients with ischemic heart disease.

The aim of the article is to review the literature data about the significance and problems of the QT dispersion and heart rate variability in sudden death risk stratification in patients with coronary heart disease. QT dispersion is defined as the difference between the longest and the shortest QT intervals as measured in the 12-lead electrocardiogram. A direct relationship between the prolongation of QT dispersion and myocardial ischemia has been reported by several authors. Our previous study showed that QT dispersion assessed immediately after bicycle exercise test was significantly higher in patients with coronary stenoses of > 50% as compared to the patients without coronary artery disease. Despite some controversial data, several studies showed that QT dispersion is a significant predictor of cardiovascular mortality. Heart rate variability representing a relationship between the autonomic nervous system and cardiovascular mortality, including sudden cardiac death, is one of the most promising markers. The predictive value of heart rate variability is independent of other factors established for postinfarction risk stratification, such as depressed left ventricular ejection fraction, increased ventricular ectopic activity, and presence of late potentials. For prediction of all-cause mortality, the value of heart rate variability is similar to that of left ventricular ejection fraction, but heart rate variability is superior to left ventricular ejection fraction in predicting arrhythmic events (sudden cardiac death and ventricular tachycardia).

Cardiotonic Agents↗

PubMed2005

Non-linear heart rate variability and risk stratification in cardiovascular disease.

Traditional time and frequency domain heart rate variability (HRV) have cardiac patients at risk of mortality post-myocardial infarction. More recently, non linear HRV has been applied to risk stratification of cardiac patients. In this review we describe studies of non linear HRV and outcome in cardiac patients. We have included studies that used the three most common non-linear indices: power law slope, the short term fractal scaling exponent and measures based on Poincare plots. We suggest that a combination of traditional and non-linear HRV may be optimal for risk stratification. Considerations in using non linear HRV in a clinical setting are described.

Journal Article↗

PubMedDate not supplied

[Clinical stratification of cardiogenic shock].

Cardiogenic shock (CHC) associated to acute myocardial infarct has high mortality and their manifestations are heterogenous. In our institution historical mortality, was 98%, but with different methods of reperfusion, its reduced to 53%. In other hand, with opportune clinical stratification is useful to improve the treatment strategy. This stratification on basis in clinical signs: age, infarction location, cardiac frequency and systemic arterial pressure, and hemodynamical valuation with the use of right catheterism with quantification miocardial work parameters like "Cardiac power" that is the product of flow and arterial pressure and that is of utility to know the "Miocardial reserve". In our experience after reperfusion procedure patients with CHC and cardiac power less than 1.0 had highly mortality.

Cardiac Output↗

PubMed1991

Stratification of multiple myeloma according to serum beta 2-microglobulin and serum albumin levels.

In 71 patients with multiple myeloma the authors evaluated the clinical significance and the prognostic relevance of Bataille's stratification system based on serum beta 2-microglobulin and serum albumin levels. This staging system, which classified the patients to low, intermediate and poor risk groups (stages 1-3) showed a rather small prognostic significance, and it stratified our myeloma patients unsatisfactorily. On the basis of the results of our own analyses, we have developed our own modification of a pilot stratification system. We have verified its good clinical applicability and its powerful prognostic prediction. In this study, the good prognostic significance of serum beta 2-microglobulin and albumin levels (with the best cut-off levels of 4.0 mg/l and 35.0 g/l) and a good correlation between both analysed markers were confirmed.

Adult↗

PubMed1990

Development of a methodology for malariogenic stratification as a tool for malaria control.

Modified plan of operation (MPO) for malaria control launched in 1977 failed to curb malaria incidence beyond about 2 million cases per annum and thus necessitated development of multipronged malaria control strategies based upon malariogenic stratification. A model for such stratification based upon six most sensitive, but quantifiable, epidemiological parameters for which records are easily available at PHC level, namely, topography, average annual rainfall, vector(s), average annual parasite incidence (API) for the last five years, epidemic potential and vulnerability was developed. This model has been successfully tried in the State of Karnataka and on that basis the whole State has been divided into five strata in order of increasing endemicity. Objectives of malaria control for each of the stratum so defined have been proposed.

Animals↗

PubMed1990

Risk stratification and management of patients with organic heart disease and nonsustained ventricular tachycardia: role of programmed stimulation, left ventricular ejection fraction, and the signal-averaged electrocardiogram.

PURPOSE: Programmed stimulation, left ventricular ejection fraction, and signal-averaged electrocardiography were performed in patients with organic heart disease and spontaneous nonsustained ventricular tachycardia (VT) to determine the role of these techniques in risk stratification and management. PATIENTS AND METHODS: The study consisted of 90 patients: 63 had coronary artery disease and 27 had idiopathic dilated cardiomyopathy. Radionuclide ventriculography, signal-averaged electrocardiography, and programmed electrical stimulation were performed in all patients within 48 hours of index ambulatory electrocardiography. RESULTS: Fifty-three patients (59%) had an ejection fraction less than 40%. Programmed stimulation induced sustained monomorphic VT in 22 patients (24%), ventricular fibrillation (VF) in 10 patients (11%), and no sustained VT/VF in 58 patients (64%). The signal-averaged electrocardiogram (ECG) showed late potentials in 23 patients (26%). Sustained monomorphic VT could be induced in 65% of patients with late potentials and in 10% of those without late potentials. There was no case of inducible sustained monomorphic VT in 33 patients with no late potentials and an ejection fraction of 40% or greater. All patients with induced sustained monomorphic VT received antiarrhythmic therapy guided by the results of programmed stimulation. All 58 patients with no induced sustained ventricular tachyarrhythmias and eight patients with induced VF were discharged without receiving antiarrhythmic drugs. During a follow-up of 30 +/- 10 months, the three-year sudden death rate was 19% in patients with induced sustained VT, 0% in those with induced VF, and 9% in those with no induced sustained VT/VF. The three-year sudden death rate was the same (7%) in patients with no induced sustained VT/VF, both in those with an ejection fraction of 40% or greater or less than 40%. On the other hand, the three-year total cardiac mortality was significantly higher (27%) in those patients with ejection fractions less than 40% compared to those with ejection fractions of 40% or greater (7%). CONCLUSION: It is concluded that the signal-averaged ECG, ejection fraction, and programmed stimulation could be used for the risk stratification and management of patients with organic heart disease and nonsustained VT as follows: (1) Patients with no late potentials and with an ejection fraction of 40% or greater do not require invasive evaluation or antiarrhythmic therapy, since the incidences of induced VT and sudden death are very low. (2) Patients with late potentials as well as patients without late potentials but with an ejection fraction of less than 40% may be advised to undergo electrophysiologic evaluation.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Arrhythmia Agents↗

PubMed1977

Racial stratification of organochlorine insecticide residues in human adipose tissue.

The racial stratification of residues of total DDT equivalent, heptachlor epoxide, oxychlordane, dieldrin, beta-benzene hexachloride and lindane in human adipose tissue was studied. Samples of human adipose tissue were obtained from locations selected in the contiguous United States according to a stratified, proportionate-random survey design and chemically analyzed for selected organochlorine pesticides. The most marked case of racial difference in residue level was total DDT equivalent. Samples from Negros contained almost twice as much of this chemical as did samples from Caucasians. Racial stratification also was found in the frequency of lindane. Lindane was detected about twice as often in samples from Negros than in samples from Caucasians. Little racial differences were noted for residues of beta-benzene hexachloride, heptachlor epoxide, dieldrin and oxychlordane.

Adipose Tissue↗

PubMed1983

Factors associated with prognosis in human breast cancer. II. Multivariate stratification analysis.

Prediction of the individual fate of breast cancer patient is one of the most important problems for establishment of therapeutic plans. We have analyzed the relationships of clinical factors to 3-year and 8-year survivals in a series of 400 patients treated for breast carcinoma. Multivariate stratification analysis for obtaining subgroups with different survivals was performed with the aid of Bintree, a computer program which produces binary splits of a population according to the criterion of maximal reduction of variance, and generates a binary stratification tree. Lymph node status was the major predictor for both short and long term prognosis but had no important role in the survival of patients who relapsed. Antecedent abortions were related to less relapses. Age, previous benign breast diseases, nulliparity and lactation conditioned better prognosis without association with relapse probability, indicating an association with the speed of evolution of the disseminated disease. In general clinical data were insufficient for establishment of good and bad prognosis polar groups of patients, especially in patients in which no clinical lymph node involvement was recorded.

Adult↗

PubMed1983

Post-stratification in the randomized clinical trial.

A topic of current biometric discussion is whether stratification should be used in randomized clinical trials and, if so, which kind. An approach based upon randomization theory is used to evaluate pre- versus post-stratification. The results obtained relate specifically to the effect of the size of the clinical trial on the bias and precision of estimated treatment contrasts.

Biometry↗

PubMed1995

[Current malaria stratification in China].

During the past 30 years since 1958 when malaria stratification was first made, a great change in malaria situation has occurred. The original stratification can not represent the current status of malaria distribution. Therefore, it needs to be redivided so as to provide basis for future malaria control work. Taking species of mosquito vector and malaria incidence as the main indices and making reference to the natural geographical division, the current malaria endemic area in China can be divided into four regions, i.e. (1) Western region: it is mostly a natural non-endemic area, except some limited areas with sporadic cases in Xinjiang Autonomous Region; (2) Northern region: the whole north-eastern and partial northern China belong to the areas where malaria has been basically eliminated; but sporadic occurrence still exist in most part of the northern China; (3) Central region: it is mostly a hypo-endemic area, only a small part has meso-endemicity; (4) Southern region: nearly 50% has meso-endemicity and the other 50% has hypo-endemicity. The demarcation line of natural non-endemic areas and the areas where malaria has been basically eliminated has been defined.

Animals↗

PubMed1994

Stratification in nonparametric ROC studies.

In many clinical experiments it is clear that external factors can affect the performance of diagnostic tests as these factors influence the distributions of separator variables. The authors investigate how stratification of cases and/or controls can be used in nonparametric received operating characteristic (ROC) studies, and develop statistical methods using stratification. The method can be used to simultaneously assess the ability of a diagnostic marker against several types of controls or cases. This allows a new method for the assessment of diagnostic tests.

Analysis of Variance↗

PubMed1993

[Risk stratification in non-Q-wave myocardial infarct].

There was been some controversy about non-Q wave myocardial infarction, its evolution and prognosis. The most recent studies showed that, in spite of the low immediate mortality in non-Q wave myocardial infarction, the long-term risk of ischaemia, reinfarction or sudden death is equal or even greater than in the Q-Wave myocardial infarction. In order to define an adequate ischaemic risk stratification strategy in the post non-Q wave myocardial infarction without complications, the authors studied 21 patients who were submitted to treadmill exercise test and coronary angiography within 30 days after the acute event. Of the 17 patients with positive stress testing, 14 showed significant relationship between ischaemic area detected in the stress testing and the anatomic localization and severity of the lesions in the coronary angiography (chi 2 = 14,875; p < 0.006). Revascularization therapy (PTCA or bypass surgery) was very high in this group of patients (47.6%). From the date obtained the authors conclude that it is not necessary to use invasive studies in every patient that has suffered from non-Q wave myocardial infarction without complications, since the stress testing showed high sensitivity (94.4%), specificity (75%) and high predictive value (100%) in the ischaemic risk stratification.

Chi-Square Distribution↗