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PubMed1999

Elite formation under occupation: the internal stratification of palestinian elites in the West Bank and Gaza Strip.

This paper examines the internal stratification of Palestinian elites in the West Bank and Gaza Strip under Israeli occupation. Our general aim is to clarify the extent to which social and political subordination to outside rule influences the development of indigenous elites in stateless societies. In contrast to nation-state societies, such elites may be horizontally stratified into a wider range of institutional settings, and vertically stratified by anti-occupation activism alongside the attainment of occupational prestige. In addition, context-specific determinants of their stratification patterns, such as refugee status, regionality, and country in which educational credentials were acquired, should be considered. A secondary content analysis of interviews conducted by the Palestinian Panorama centre with 249 elite members reveals, that the vertical stratification of Palestinian elites along occupational attainment and anti-occupation activism constitutes two quite independent status dimensions. A multinomial logit regression shows that, horizontally, elite groups are embedded in four distinct types of institutional activity, further demonstrating the multi-faceted formation of Palestinian elites. Contextual resources, such as refugee versus non-refugee status, regionality, and the acquiring of Western credentials, have differential effects on the vertical and horizontal stratification of Palestinian elites. The implications of these findings for further research on elite formation in the post-Oslo Palestinian society and in other stateless societies are discussed in conclusion.

Adult↗

PubMed1998

Stepwise strategy on the cost of risk stratification after acute myocardial infarction: a retrospective simulation study.

Stratification of postinfarction patients at high risk of mortality and/or other adverse events can be improved by combining several prognostic markers. As the clinical impact of risk stratification has only recently emerged in prospective trials, there are a lack of data regarding the cost-effectiveness of multimarker strategies. This study performed a comprehensive search of a postinfarction database and simulated different risk stratification strategies involving left ventricular ejection fraction, signal-averaged electrocardiography, Holter monitoring, and heart rate variability, The parameters were assessed before discharge in 417 survivors of acute myocardial infarction followed-up for 1 year. Cardiac mortality was used as the clinical endpoint. A statistical computer model of a stepwise strategy using every feasible sequence of the four tests was used and, based on prices derived from European and American centers, the cost estimates of all possible combinations were compared. During the 1 year after myocardial infarction there were 24 cardiac deaths (5.8%). In all the population, 6% had all four tests positive (cardiac mortality 20%); 25% had at least three tests positive (cardiac mortality 12.5%); 58% had at least two tests positive (cardiac mortality 8.3%); and 92% presented with at least one test positive (cardiac mortality 6.3%). The cost of performing all the tests ranged between $398 and $1,887 for each patient. However, by selecting patients according to a step wise strategy, the costs ranged from $96 (> or = 1 test positive) to $510 (for the least expensive sequences of four tests positive). For each of the centers considered, the costs resulting from the risk stratification protocol were determined by the number of variables combined and sequences of tests adopted. Thus, a step wise strategy using the combination of all four parameters, starting with analysis of Holter variables and finishing with signal-averaged electrocardiography, appears to be the most appropriate and the least expensive approach for selecting patients at high risk of cardiac death.

Computer Simulation↗

PubMed1976

The early posthospital phase of myocardial infarction. Prognostic stratification.

Prognostic stratification was carried out on 518 patients less than or equal to 65 years of age who were discharged from the hospital following a definite or probable acute myocardial infarction and followed for four months. The total population was made up of 272 patients hospitalzed in 1973 and 246 patients hospitalized in 1974; one hundred and forty-two variables were collected on each patient. The clinical characteristics of the 1973 and 1974 populations were remarkably similar, and both groups had a four-month posthospital cardiac mortality rate of 4%. Two prognostic stratification schemes were developed on the 1973 population which identified low and high risk groups with meaningfully different four-month cardiac death rates. Both stratification schemes were tested on the 1974 population, and one of the two schemes was validated as identifying a significantly increased cardiac mortality rate in the high as opposed to the low risk group. The four-month posthospital cardiac mortality rate was 3% in the low and 14% in the high risk group (Z = 2.70, P less than 0.003). The high risk group was characterized by two or more of the following characteristics: 1) history of angina at ordinary levels of activity or at rest; 2) CCU hypotension and/or congestive heart failure; 3) ventricular premature beat frequency greater than or equal to 20/hr on a six-hour electrocardiographic tape recording. The low risk group had none or only one of the above characteristcis. The prognostic power of this stratification scheme is such that sixteen percent of the posthospital population can be identified as high risk, and this subgroup contains forty-six percent of the patients who die of cardiac cause in the four-month posthospital interval.

Aged↗

PubMed1997

Cardiac risk stratification for high-risk vascular surgery.

BACKGROUND: The best strategy for cardiac risk assessment before high-risk vascular surgery remains controversial. A cardiac risk stratification protocol was evaluated in patients undergoing high-risk vascular surgery. Our investigation paralleled the elaboration of the American College of Cardiology/ American Heart Association (ACC/AHA) Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery and is highly comparable to the proposed guidelines. METHODS AND RESULTS: A cardiac risk stratification protocol was evaluated prospectively in 203 patients scheduled for aortic surgery. Key points of the study were cardiac mortality/morbidity and cost-effectiveness. Patients were stratified into low (n = 101), intermediate (n = 79), and high (n = 23) cardiac risk after clinical predictors. After stratification, the degree of estimated functional capacity assessed by treadmill exercise and daily living activities and expressed by metabolic equivalents (METs) was critical for further cardiac evaluation. In intermediate-risk patients with an estimated functional capacity < 5 METs and in all high-risk patients, noninvasive cardiac testing and/or subsequent medical care were performed. Noninvasive testing was considered necessary in 41 patients, coronary angiography in 7, and myocardial revascularization in 1. Overall hospital mortality was 3.5%. Cardiac mortality and morbidity were 1% and 12.4%, respectively. CONCLUSIONS: Cardiac risk stratification for high-risk vascular surgery patients, according to a protocol similar to the ACC/AHA Guidelines for Cardiovascular Evaluation for Noncardiac Surgery, demonstrated excellent clinical outcome. This approach appears to be a safe and economical strategy for preoperative cardiac evaluation.

Aorta↗

PubMedDate not supplied

Critical appraisal of cardiac risk stratification before elective vascular surgery.

This study was undertaken to evaluate the efficacy of the cardiac risk stratification protocol proposed by the American College of Cardiology/American Heart Association (ACC/AHA) in predicting cardiac morbidity and mortality associated with elective, major arterial surgery. Cardiac risk stratification using ACC/AHA guidelines was done on 425 consecutive patients before 481 elective cerebrovascular (n = 146), aortic/inflow (n = 166), or infrainguinal (n = 169) procedures at an academic Veterans Affairs Medical Center. Cardiac risk was stratified as low, intermediate, or high based on clinical risk factors, such as, Eagle criteria, history of cardiac intervention, patient functional status, results of noninvasive cardiac stress testing, and coronary angiography with coronary revascularization performed when appropriate. Outcomes (myocardial infarction, unstable angina, congestive heart failure, ventricular arrhythmia, cardiac death, and mortality) within 30 days of surgery were compared between the various risk stratification groups. Univariate and multivariate analyses were used to identify clinically useful prognostic variables from the preoperative cardiac evaluation algorithm. Overall mortality (1.7%), cardiac death (0.4%), and adverse cardiac event (4.8%) rates were low, but cardiac death and morbidity were increased (p < 0.05) in high-risk stratified patients (3.4%, 11.9%) compared to intermediate (0%, 2.8%) and low (0%, 4.0%) cardiac risk groups. The presence of 3-vessel angiographic coronary artery occlusive disease was an independent predictor of cardiac morbidity, while inducible ischemia by cardiac stress imaging was not. Previous coronary revascularization was associated with increased mortality as was the development of a non-cardiac complication. Cardiac risk assessment identified 78 (18%) patients with indications for coronary angiography. Angiographic findings resulted in coronary artery intervention (9-angioplasty; 4-bypass grafting) in 13 (3%) patients who experienced no adverse cardiac events after the planned vascular surgery (15 procedures). Cardiac risk stratification using ACC/AHA guidelines can predict adverse cardiac events associated with elective vascular surgery; however, protocol modification by increased reliance on Eagle criteria and less use of cardiac stress testing can improve identification of the "highest risk" patients who may benefit from prophylactic coronary intervention.

Adult↗

PubMed2005

Stratification, blinding and placebo effect in a randomized, double blind placebo-controlled clinical trial of gold bead implantation in dogs with hip dysplasia.

UNLABELLED: The purpose of this study was to investigate the need for and choice of stratification factors, and the effects of blinding and placebo in a clinical experiment. Eighty dogs with canine hip dysplasia (CHD) were included in a randomized, placebo-controlled and double blind clinical trial with stratified parallel group design, in which body weight and degree of CHD were used as stratification factors. Thirty-eight dogs were allocated to gold bead implantation and 42 to placebo. After six months, 33 of the 42 placebo-treated dogs received gold bead implantation in an open study lasting a further 18 months. The main outcome variable in the study was change in pain signs of CHD as assessed by the owner. No significant difference in the main outcome variable, regardless of the treatment given, could be detected in the two chosen stratification factors. The only factor to influence the main outcome variable significantly was age. The blinding procedure used in the study, in which 60% of the owners correctly guessed the treatment given, was found sufficient. Of those who guessed the treatment erroneously, 88% believed the treatment given was gold bead implantation. The treatment efficacy after six months in the blinded treatment group was found to be significantly larger compared to the efficacy obtained in the open study. A significant placebo effect was therefore detected. CONCLUSION AND CLINICAL RELEVANCE: The age of the dogs influenced the outcome of the CHD treatment, and is recommended as a stratification factor. A significant placebo effect has to be expected and an optimal blinding procedure is necessary in similar clinical studies.

Age Factors↗

PubMed1997

Risk stratification after myocardial infarction.

PURPOSE: To review the literature on risk stratification after acute myocardial infarction in the reperfusion era and to propose an algorithm for early and continual risk assessment. DATA SOURCES: A MEDLINE search of the English-language literature on humans was done using the terms myocardial infarction, prospective studies, and prognosis. This search was supplemented by narrowed searches for subheadings (such as cardiogenic shock, thrombolytic therapy, and stress testing) and surveys of references cited in review articles and book chapters. STUDY SELECTION: Literature on prognosis and myocardial infarction published from 1981 to 1996 was considered. From the literature on stress testing methods, studies that enrolled patients before 1980, enrolled patients for indications other than myocardial infarction, tested patients more than 6 weeks after infarction, were missing outcome data, or had inadequate follow-up were excluded. DATA EXTRACTION: Because too few randomized trials were available to allow the cross-comparison of risk-stratification methods, the available observational data were synthesized and supplemented with clinical judgments to produce recommendations. DATA SYNTHESIS: Risk stratification must begin when acute myocardial infarction is diagnosed. High-risk patients (such as those with cardiogenic shock) and candidates for reperfusion therapy must be identified quickly if ideal emergency care is to be given. At specific points during hospitalization, specialized tests may be useful if they add incremental information to the results of clinical evaluations. High-risk patients who have complications after infarction or significant left ventricular dysfunction probably benefit from early angiography; patients without these conditions are at low risk for recurrent events and should have noninvasive stress testing for further risk stratification. CONCLUSIONS: Physicians should continually reappraise risk throughout hospitalization to optimize both patient outcomes and cost containment.

Algorithms↗

PubMedDate not supplied

Comparison of dermatoscopic ABCD rule and risk stratification in the diagnosis of malignant melanoma.

For didactic and documentation purposes the dermatoscopic ABCD rule and the dermatoscopic risk stratification have been proposed. The aim of this investigation was to compare the ability of the 2 methods to separate patients with cutaneous malignant melanoma from individuals with other pigmented skin lesions. Three dermatologists, experienced users of dermatoscopy, assessed macroscopic clinical and dermatoscopic slides from 258 patients referred to the skin cancer outpatient clinic by the ABCD rule and risk stratification methods. Diagnostic performance of the 2 methods was compared by receiver operating characteristics curve analysis. When all pigmented skin lesions were compared, there was a trend for the observers to perform better using risk stratification. When only lesions with a well-defined pigment network were included, the diagnostic performance of the risk stratification method was superior to the dermatoscopic ABCD rule (areas under the receiver operating characteristics curve median 0.93 vs. 0.80, p<0.004) for all observers. The agreement between the 2 methods was moderate to substantial (kappa coefficient 0.53-0.62). More melanomas were identified when the rules were combined. The dermatoscopic ABCD rule has been accepted as a standard for identifying melanomas with the dermatoscope, but should be considered secondary to pigment network analysis.

Biopsy, Needle↗

PubMed1998

Risk stratification by treadmill testing in acute myocardial infarction following thrombolytic therapy.

Survivors of acute myocardial infarction (AMI) should have risk stratification for assessment of their future risk of cardiovascular events. One of the important means of risk stratification is by treadmill test (TMT). Most of the algorithms for assessment were done in the prethrombolytic era. But in the post-thrombolytic era, risk stratification by TMT should be properly evaluated. Fifty males with confirmed AMI with age ranging from 38-62 years (mean 48 years) were tested with a symptom limited (Modified Bruce Protocol) TMT. The patients were followed up for a minimum of 6 months (range 6-10 months). Out of 50 patients, 38 reported for follow up. Among them 22 (Group A) had cardiac events and 16 (Group B) had no events. Among the patients (Group A), 6 had unstable angina, 7 had reinfarction, 2 had sudden death, 4 had coronary artery bypass grafting (CABG) and 3 had angioplasty. Comparison between the two groups, A and B in TMT parameters like ST segment depression > 2.5 mm (12 vs 9), no. of leads where ST depression occurred (66 vs 48) during exercise, mean work capacity (8.1 vs 7.9 mets), mean systolic blood pressure response were all statistically insignificant. Though TMT was believed to be a good prognostic indicator to assess further cardiac events after AMI, its efficacy in risk stratification after thrombolysis is yet to be determined. This study does not show its worth in post MI risk assessment.

Adult↗

PubMed2002

[Roaming through methodology. XXXVII. Unintentional population stratification in genetic case-control studies].

In the field of genetic epidemiology, the appropriate selection of patients and controls within a case-control study is essential to obtain accurate results. Within the genetic case-control study design, unintentional population stratification can cause confounding of results. The probability of this type of confounding arising is determined by the selection of cases and controls from different populations and by the differences in their genetic background. In follow-up studies, confounding by population stratification may also occur. Recent developments in the fields of statistics and genetics now make it reasonably simple to test for population stratification in case-control studies, and to prevent confounding by this stratification.

Case-Control Studies↗

PubMed2004

[The stratification of moisture content and its dynamics in co-composting of sewage sludge and pig manure].

The experiment of co-composting of sewage sludge and pig manure was studied. The moisture contents were 50.82%-60.87% at the stage of temperature rising and 38.7%-52.17% at the stage of thermophilic fermentation, and the stratification of moisture content were not obvious for both stages because the door, the internal wall and the depth of the composting bay had little effect on the stratification. At the stage of cooling, the moisture content was 24.54%-49.39%, and the stratification of moisture content was remarkable as the door, the internal wall and the depth of the composting bay had great influence on it. At the stage of maturity, the moisture content was 19.18%-49.34%, and the stratification of moisture weakened, for which the door and the internal wall were mainly responsible. At the different composting stage, the degree of difference of moisture content on the profiles of the pile was of the order: maturity stage > cooling stage > thermophilic stage = temperature rising stage, and the moisture content in the pile was as follows: the lower > the middle > the upper. The relation between moisture content and composting time meeted with two-order kinetics equation.

Animals↗

PubMed1995

Risk stratification after myocardial infarction. Clinical evaluation before discharge.

Risk stratification after an acute myocardial infarction suffered a remarkable evolution in the last few years. These improvements were mainly related to the development of reperfusion strategies that changed radically the way we managed acute myocardial infarction. Risk stratification in the reperfusion era occurs in three according to time from admission: Phase I (first 24 hours), Phase II (days 2 to 5), and Phase III (predischarge). In the last years the development of new technologies permitted the study of areas not usually explored in risk stratification, as heart rate variability (autonomic system activation), and signal-averaged electrocardiogram (arrhythmia's substrate). However, risk stratification is an issue that is far from being closed, a lot of controversy still exists in some areas, and new frontiers are emerging in front of us.

Death, Sudden, Cardiac↗

PubMed1994

Normal human urothelial cells in vitro: proliferation and induction of stratification.

BACKGROUND: The purpose of the work was to establish urothelium as an in vitro model for the study of proliferation, stratification, and differentiation in "complex" epithelia. EXPERIMENTAL DESIGN: Normal human urothelial cells were cultured in a serum-free medium. The effects of epidermal growth factor (EGF), cholera toxin (CT), extracellular calcium and 13-cis-retinoic acid on cell growth, morphology, phenotype, and cytodifferentiation were studied using phase-contrast microscopy and indirect immunofluorescence. Stratification-related changes were additionally analyzed by transmission electron microscopy. RESULTS: Under optimized conditions, long-term cultures were successful in 44 (74.5%) out of 59 specimens. Bacterial infection was the most common cause of failure (9 cases). Primary urothelial cells required an initial plating density of > or = 10(4) cells/cm2 for survival; passaged cells survived much lower plating densities (> or = 2.5 x 10(2) cells/cm2). CT significantly improved cell attachment, but neither CT nor EGF were essential for growth. By contrast, cells failed to proliferate without bovine pituitary extract. In media containing bovine pituitary extract, CT, and EGF, cultures had a mean population doubling time of 14.7 +/- 1.8 hours, maintained a nonstratified phenotype, and expressed the cytokeratin (CK) profile of basal/intermediate urothelium: CK7, CK8, CK17, CK18 and CK19, with variable expression of CK13. CK20 was not expressed in vitro. CK14 and CK16 were also expressed, suggestive of squamous metaplasia in culture, which could be inhibited with 13-cis-retinoic acid. Increasing extracellular calcium from 0.09 to 0.9-4.0 mM slowed cell proliferation, induced stratification and desmosome formation, and increased expression of E-cadherin. High calcium, EGF, CT, and retinoic acid did not induce markers of late/terminal urothelial cytodifferentiation. CONCLUSIONS: We describe a simplified technique for the isolation and long-term culture of human urothelial cells. Urothelial cells in vitro are capable of rapid proliferation and can be induced to form integrated stratifying cell layers in high calcium medium. Stratification-related changes are not necessarily accompanied by urothelial cell maturation and differentiation.

Adolescent↗

PubMed2026

Identifying gene expression signatures for risk stratification of postoperative adjuvant chemotherapy in colorectal cancer.

Clinical risk stratification for postoperative recurrence in patients with pathological stage II (pStage II) colorectal cancer (CRC) is essential for guiding the use of postoperative adjuvant chemotherapy (ACT). In this study, we identified novel prognostic gene expression biomarkers in patients with pStage II CRC and developed a new risk stratification framework for ACT decision-making. First, genome-wide biomarker discovery was conducted to identify prognostic gene expression biomarkers associated with recurrence risk in pStage II CRC. This analysis identified 10 differentially expressed genes as potential biomarkers for recurrence. The efficacy of these biomarkers was then tested using 188 clinical surgical specimens obtained from patients with pStage II CRC. A predictive panel was developed using qRT-PCR and used to assess 93 clinical specimens with an area under the curve (AUC) of 0.82, and its performance was further validated in an independent cohort (n = 95). By incorporating key clinicopathological features, a Gene expression-based Prediction of Recurrence in pStage II CRC (GPRSC) signature was developed, which robustly predicted postoperative recurrence (AUC: 0.80). Finally, combining the GPRSC signature, microsatellite instability status, and conventional criteria, we developed a novel risk stratification system for postoperative ACT decision-making in pStage II CRC. Overall, we identified novel gene expression biomarkers and developed a prognostic signature that informs clinical decision-making regarding postoperative ACT in patients with pStage II CRC.

Humans↗

PubMed2000

Forest Canopy Stratification-Is It Useful?

It has long been recognized that the forest canopy has a complex structure that is significant for environmental interactions, regeneration, growth, and biotic habitat. Not only is the structure variously complex, but also there are many ways to conceptualize that complexity. Yet the persistent theme when considering the structure of canopies continues to be that of stratification: whether structural units are arranged in layers above the ground. We examined the use of the terms "stratification," "layering," and others in connection with canopy structure and found they had various meanings (often only implied) that were difficult to reconcile and to measure. We applied the definitions to the structure of a single, well-studied canopy located in Virginia, U.S.A., and found they failed to define consistently and clearly the presence, number, or location of strata. Additionally, we found the concept had limitations related to scale dependence, point of reference, and spatial averaging. Thus, asserting that a forest is stratified or naming the number of layers generally provided no guide to its structure. We propose alternative ways of conceptualizing and studying the forest canopy that avoid most of the problems associated with stratification. Among these are direct measurement and mapping of structural and environmental variables that have clear potential connections with canopy functions and viewing the distribution of structures or environmental conditions within the canopy as ecological gradients.

canopy↗

PubMed2026

The Sociogenomics of Social Stratification and General Theories of Inequality.

The field of the sociogenomics of inequalities would benefit from discussing what its findings and ambitions mean for core theories of social stratification and mobility. Do sociologists need to reconsider their critique to structural-functionalist theory of stratification, and its neo-classical economic allies, that emphasise efficient sorting of individuals to social positions? Or do their interpretations of genetic correlates of inequality need to include reference to constructivist processes that have defined the genetic mix that has come to be rewarded in a society? I argue that, with the current sociogenomics methods, it is hard to disentangle these theories, which are however fundamentally different regarding the nature and structure of social stratification. Using simulations that distinguish context-dependent from context-independent genetic variability, it is shown that the field always needs to make untestable assumptions about the nature of genetic differences.

Humans↗

PubMed2006

Immunohistochemical profiling based on Bcl-2, CD10 and MUM1 expression improves risk stratification in patients with primary nodal diffuse large B cell lymphoma.

Clinical outcome in patients with diffuse large B cell lymphomas (DLBCL) is poorly predictable. Expression of proteins related to germinal centre B (GCB) cell or activated B cells (ABC) and expression of apoptosis-regulating proteins Bcl-2 and XIAP have been found previously to be strongly associated with clinical outcome. In this study we aimed to develop an algorithm based on expression of GCB/ABC-related proteins CD10, Bcl-6 and MUM1 and apoptosis-inhibiting proteins Bcl-2, XIAP and cFLIP for optimal stratification of DLBCL patients into prognostically favourable and unfavourable groups. Expression of CD10 and cFLIP was associated with better overall survival (both p = 0.03), whereas expression of MUM1, Bcl-2 and XIAP was associated with poor clinical outcome (p = 0.01, p = 0.0007 and p = 0.03, respectively). Multivariate analysis revealed that Bcl-2 was the strongest prognostic marker followed by CD10 and MUM1. Stratification of patients according to a new algorithm based on expression of these three markers improved patient risk stratification into low and particularly high clinical risk groups (p = 0.04 and p < 0.0001, respectively). We conclude that, in our group of primary nodal DLBCLs, a new algorithm, based on expression of the apoptosis-inhibiting protein Bcl-2 and the GCB/ABC-related proteins CD10 and MUM1, strongly predicts outcome in International Prognostic Index (IPI)-low and -high patients. Its predictive power is stronger than previously published algorithms based on only GCB/ABC- or apoptosis-regulating proteins.

Adult↗

PubMed2002

Choice of stratification in Poisson process analysis of recurrent event data with environmental covariates.

The Poisson process approach for studying the association between environmental covariates and recurrent events depends on the stratification of study period into intervals within which the baseline intensities are assumed constant. In this work we investigate the problem of bias and variance due to misspecification of this stratification. We suggest a cross-validation approach to choosing a stratification model to balance the trade-off between bias and variance. We also establish a connection between the Poisson process approach and case cross-over studies.

Air Pollution↗