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Results for “prognostic stratification”

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PubMed1995

Molecular analysis of infant acute lymphoblastic leukemia: MLL gene rearrangement and reverse transcriptase-polymerase chain reaction for t(4; 11)(q21; q23).

Molecular techniques to detect MLL (11q23) and AF-4 (4q21) gene rearrangements are being evaluated for use in stratification of patients into prognostic groups. We studied 15 cases of infant acute lymphoblastic leukemia (ALL) with Southern blotting for MLL gene rearrangement and reverse transcriptase-polymerase chain reaction (RT-PCR) for t(4;11) fusion transcripts and compared the results to cytogenetic and clinical data. Our results indicate that classic t(4;11)(q21;q23) translocations are detected by RT-PCR; however, unusual 4;11 translocations still require additional investigation. We also extended and updated our original study of MLL gene rearrangement in infant ALL to 40 patients with longer follow-up and show that the group with germline configuration of the MLL gene continues to have an excellent outcome. The results of salvage therapy (bone marrow transplantation or chemotherapy) suggest that transplant may show advantage. Preliminary results of the use of RT-PCR to assess minimal disease are also reported.

Antineoplastic Combined Chemotherapy Protocols↗

PubMedDate not supplied

[Therapeutic trials in Alzheimer disease. Selection--recruitment and stratification].

Therapeutic trials conducted in Alzheimer's disease have benefited from the standardization of diagnostic criteria based on internationally recognized scales (DSM III-R, NINCDS-ADRDA) which ensure more valid inclusions. Well specified exclusion criteria are also of the utmost importance, in particular depression, vascular dementia and concomitant psychotropic drugs. Cognitive and/or functional scales allow an appreciation of the severity of the disease. Due to the heterogeneity of Alzheimer's disease stratification methods on identified prognostic factors i.e. aphasia, extrapyramidal symptoms should be performed. Selection of responders during an enrichment phase has still to be discussed. Multicentric studies become imperative because of the large number of patients required and the difficulties in selecting the adequate patients. These raise the issues of investigators' experience, coordination and between center variability.

Alzheimer Disease↗

PubMedDate not supplied

Predictors of prognosis in patients awaiting heart transplantation.

Patients enrolled in a clinical heart transplantation program were evaluated to identify the predictors of prognosis in patients with advanced heart disease and to optimize timing of heart transplantation. Three hundred eighty-eight subjects were consecutively evaluated from 1985 through 1989. One hundred eighty-four patients (47.5%) had dilated cardiomyopathy; 164 patients (42.2%) had ischemic heart disease; 34 patients (8.8%) had valvular heart disease, and six patients (1.5%) had miscellaneous disorders. In each patient, 45 different parameters were considered. During follow-up (mean, 8.4 months) 166 patients underwent heart transplantation; 99 patients died (heart failure, 66 patients; sudden death, 26 patients; thromboembolism, two patients; noncardiac causes, five patients). The actuarial survival was 83% at 3 months, 77% at 6 months, 73% at 9 months, 70% at 1 year, and 59% at 2 years. The median survival time was 28 months. Analysis by Cox proportional hazard regression model revealed seven independent and significant prognostic factors: etiology (p < 0.05), NYHA class (p < 0.05), third heart sound (p < 0.05), diastolic pulmonary artery pressure (p < 0.05), pulmonary wedge pressure (p < 0.01), mean systemic blood pressure (p < 0.05), and cardiac output (p < 0.05). Cox's analysis allows the computation of patient-specific curves for predictions of residual survival time at any moment during follow-up. Moreover it can be used to calculate a simple prognostic index, which enables stratification of the patient population into three risk classes: patients at high (n = 105), intermediate (n = 160) and low (n = 123) risk of early death. Pairwise comparisons of survival between the classes were significant at 1% level.

Adolescent↗

PubMed1997

[Molecular anomalies in malignant hemopathies].

Much of our understanding of the molecular anomalies involved in the process of oncogenesis has resulted from research into malignant hematologic diseases, facilitated by the accessibility of hematopoietic cells. For example, in lymphoid tumors, rearrangement of the genomic DNA can lead to the juxtaposition of proto-oncogenes and the highly active sequences regulating synthesis of immunoglobulins or T-cell receptors. The subsequent malignancy results from an uncontrolled overexpression of a normal protein. This type of "quantitative" anomaly occurs in follicular lymphomas where B-cells overexpress the normal BCL2 protein which inhibits apoptosis, contributing to immortalization of the B done. The same type of rearrangement process can approach gene fragments which fusion and lead to production of a highly oncogenic chimerical or truncated abnormal protein. Such "qualitative" anomalies occur in myeloid hemopathies. Both types of anomalies involve genes controlling the cell cycle, cell differentiation or cell death (apoptosis), in particular transcription factors (for example, E2A, RARA, MYC) and molecules involved in signal transduction (for example RAS, ABL, LCK). A molecular anomaly can be detected in approximately 30% of all cases of acute leukemia and in up to 75% of the non-Hodgkin lymphomas. Analysis of the junction fragments of the different heavy chains of the immunoglobulins produced in these cases provides a specific marker for detecting the B or T-cell clone in digestive or skin biopsies. For example, detection of a BCR-ABL transcript in a patient with primary thrombocythemia or an atypical myeloproliferative syndrome can be diagnostic and detection of the donal immunoglobulin or T-cell receptor rearrangement can confirm the malignant nature of the lymphoid proliferation. Molecular markers also have prognostic value allowing patient stratification and more adapted therapy. Molecular anomalies detected in malignant hematologic diseases are thus examples of nearly perfect "tumor-specific" markers.

Hematologic Neoplasms↗

PubMed1998

Molecular pathogenesis of childhood acute lymphoblastic leukemia.

This concise review focuses on the most recent advances in understanding molecular genetic abnormalities in childhood acute leukemia (ALL). An increasing number of chromosomal translocations associated to distinct molecular genetic abnormalities have been described. Recurrent motifs have been recognized behind the great heterogeneity of genes involved in chromosomal translocations occurring in childhood ALL. The expression or activation of specific genes encoding for transcription factors have been recognized to be the most frequent recurring mechanism. In addition to the identification of genes involved in translocations, the analysis of deleted or mutated genes has provided new insights into the molecular pathogenesis of childhood ALL. The understanding of the genetic heterogeneity has turned out to have great impact on routine diagnosis and treatment. Molecular analysis has revealed that the t(12;21) translocation, barely detectable when searched for by conventional cytogenetic techniques, is the most frequent genetic lesion occurring in childhood ALL. Accumulating evidence clearly indicates that molecular characterisation at diagnosis represents the most relevant prognostic information for risk stratification of the patients at diagnosis. Several target genes are now available for the study of minimal residual disease and to evaluate its potential impact for tailoring treatment. Finally, our progress in understanding the relationships between genetic lesions and environmental etiologic agents will further contribute to delineating the natural history of pediatric ALL.

Child↗

PubMed2001

Prognostic value of Doppler echocardiographic mitral inflow patterns: implications for risk stratification in patients with chronic congestive heart failure.

OBJECTIVES: This prospective study tested whether transmitral flow patterns add incremental value to peak oxygen consumption (VO2) in determining the prognosis of patients with chronic congestive heart failure (CHF) and systolic dysfunction. BACKGROUND: Peak VO2 is an objective marker of functional capacity and is routinely used as a criterion to identify heart transplant candidates. Diastolic dysfunction limits functional capacity, but its prognostic importance relative to that of peak VO2 is unknown. METHODS: Peak VO2 and mitral inflow velocities were prospectively measured in 311 consecutive patients (mean age 54 years, 84% male) with impaired left ventricular function (ejection fraction <40%; 88 patients with ischemic and 223 with dilated cardiomyopathy) who were evaluated for heart transplant candidacy. RESULTS: During a mean follow-up period of 512 +/- 314 days, 65 patients died and 43 patients underwent heart transplantation. Diastolic filling patterns, peak VO2 and left ventricular end-diastolic diameters were independent predictors of cardiac mortality. In patients with peak VO2 < or = 14 ml/min per kg body weight, the outcome was markedly poorer in the presence of restrictive filling patterns as compared with their absence (two-year survival rate 52% vs. 80%). Similarly, despite peak VO2 levels >14 ml/min per kg, the outcome was less favorable in the presence of restrictive filling patterns (two-year survival rate 80% vs. 94%). A risk-stratification model based on the identified independent noninvasive predictors separated groups into those with high (93%), intermediate (65%) and low (39%) two-year survival rates. CONCLUSIONS: Transmitral flow patterns add incremental value to peak VO2 in determining the prognosis of patients with CHF and impaired systolic function.

Blood Flow Velocity↗

PubMed1993

Prognostic factors in metastatic prostate cancer.

Androgen deprivation therapy is the initial treatment choice for metastatic disease. When enrolling patients into androgen deprivation trials, it is important to consider stratification of enrollees based on prognostic factors that have been identified as important in determining the likelihood of response. Prognostic factors are also helpful in identifying which patients are less likely to respond to treatment; this information also would help to counsel patients. Performance status is an important prognostic factor; however, its impact is minimal because the great majority of men who receive treatment for advanced disease have a normal performance status. Hemoglobin, alkaline phosphatase, and a semiquantitative grading scale for the number of metastatic foci on the bone scan are useful prognostic factors. The pretreatment serum testosterone level is a powerful prognostic factor. Patients with a low serum testosterone level have a shorter progression-free survival than men whose pretreatment serum testosterone level is above normal. The prognostic importance of pretreatment serum testosterone level has been evaluated in studies using treatment methods that lower this level to castrate levels. Recently, we found that serum testosterone level was not a prognostic factor for men taking the nonsteroidal antiandrogen, Casodex (Zeneca, Wilmington, DE), which does not alter the serum testosterone level. The pretreatment serum prostatic-specific antigen also is a prognostic factor. This antigen may be the best single method for monitoring patients in regard to response to or progression following therapy. The return of the prostatic-specific antigen level to normal (< 4 ng/ml), or the decline in the prostatic-specific antigen level of > 90% indicates a prolonged progression-free survival. In the future, it will be interesting to incorporate both the initial prognostic factors as well as monitor the prostatic-specific antigen into a multivariate analysis, which will be highly predictive of a man's response to treatment.

Acid Phosphatase↗

PubMed2006

Prognostic significance of plasma cell propidium iodide and annexin-V indices and their mutual ratio in multiple myeloma.

The aim of this study was a contemporaneous measurement of plasma cells proliferative and apoptotic activity in patients examined at the time of multiple myeloma (MM) diagnosis before initiation of chemotherapy, focussed on the following aspects: determination of prognostic significance of plasma cell propidium iodide (PC-PI) and annexin-V FITC (PC-AI) indices; optimal cut off of PC-PI and PC-AI with regard to overall survival; calculation of summary kinetic index of plasma cells (PC-PI/AI ratio) for evaluation of its prognostic importance; determination of an index (out of PC-PI, PC-AI and PC-PI/AI) showing the closest relation to prognosis of multiple myeloma. The analyzed 122 patients fulfilling SWOG multiple myeloma criteria were treated by conventional chemotherapy. Plasma cell proliferative activity was measured by means of PC-PI examined by flow cytometry using a DNA/CD138 double staining technique. For detection of plasma cells entering apoptosis (PC-AI), flow-cytometry method with annexin-V FITC and MoAb CD138 was used. The PC-PI median in 122 patients was 2.6(0.4-4.8)%. The sequence prognostic analysis showed that the optimal PC-PI cut off was 2.9% and displayed a significant relationship with overall survival (OS) (p=0.031). The group of 94 patients had PC-AI median of 5.0(1.4-24.5)%. The best statistical significance of the rate of apoptosis related to overall survival was found at cut off value of 4.4% (p=0.022). The median of overall kinetic index of plasma cells (PC-PI/AI) examined in 94 MM patients was 0.5(0.05-2.60) and the overall kinetic index was found to display a very good relationship to OS at the cut off value of 0.71 (p=0.032). All the three indices expressing various aspects of kinetics of plasma cells allow the stratification of patients into two prognostically different groups with statistically significantly different medians of overall survival: good risk - OS still undeterminable at the time of analysis; bad risk - M: OS was for PC-PI 17 months, for PC-AI 23 months and for PC-PI/AI 16 months. The ratio of both indices, i.e. PC- PI/AI, however did not bring any further contribution to overall survival/prognosis evaluation, when compared with single PC-PI and PC-AI. Results of present study indicates that the evaluation of both proliferation and apoptotic activities of plasma cells is important for prognosis thus extending possibilities of initial stratification of MMpatients into groups with different prognostic risk.

Adult↗

PubMed2001

Prediction of node-negative breast cancer outcome by histologic grading and S-phase analysis by flow cytometry: an Eastern Cooperative Oncology Group Study (2192).

Histologic evaluation and reporting of invasive breast cancer has effectively used Nottingham combined histologic grade (NCHG). This approach to predict outcome in invasive breast cancer has not been tested in multicenter cooperative trials. Histologic slides from selected breast cancer cases entered on node-negative Eastern Cooperative Oncology Group trials were assigned grades. Two pathologists evaluated cases for NCHG defined from differentiation, mitotic index, and nuclear grade. The study population consisted of separate samples from low- and high-risk strata, where low risk was estrogen receptor positive with a tumor size of less than 3 cm and high risk was estrogen receptor negative or tumor size greater than or equal to 3 cm. The rate of agreement was generally good, with 80% of cases classified the same for mitotic count and 76% of the cases classified the same for combined grade. There were no cases disagreeing from the lowest to the highest of the three categories. The median follow-up is 11.6 years, but for analysis of survival, this was truncated at 5 years. Mitotic index and combined grade as assessed by both pathologists showed significant associations with survival. High combined histologic grade was predictive for response to cyclophosphamide/methotrexate/5-fluorouracil (CMF) with survival differences at 5 years of 30% in the treated high-grade patients over the untreated patients. Overall, it is clear that pathologists can have close agreement in assignment of combined histologic grades, with highly significant prediction in univariate and borderline significance in multivariate analysis in prognostication of time to recurrence as well as survival. Thus, stratification used in these trials was highly prognostic as hoped, leaving a role for histologic grading in these relatively large tumors, more powerful than S-phase analysis in this series. In the subgroups of high-risk patients randomized between CMF and observation, there was a suggestion that the high-combined-grade group was predictive of treatment efficacy. We conclude that a combined histologic grade with defined criteria may be reliably assigned by practiced pathologists using readily available criteria, and that the measure may be of use in prognostication and prediction of therapeutic responsiveness when done in a technically ideal fashion.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2026

Development of a Computational Histology Artificial Intelligence-Powered Prognostic Biomarker in Colorectal Cancer in The Cancer Genome Atlas.

BACKGROUND: Risk stratification in colorectal cancer (CRC) plays an important role in treatment decision-making. As such, prognostic biomarkers that can augment risk stratification have clinical value. Quantitative histologic features from routine hematoxylin and eosin (H&E)-stained whole slide images (WSIs) provide a novel avenue for biomarker discovery. In this study, we explored the potential for a computational histology artificial intelligence (CHAI) platform to develop and validate a prognostic biomarker in CRC. METHODS: The Cancer Genome Atlas Colorectal Adenocarcinoma project was utilized for this study, with inclusion of all subjects (stage I-IV) with available digitized H&E specimens. The cohort was split into development and validation cohorts by a stratified random split. The previously developed CHAI platform was applied in the development cohort to construct a continuous risk score from histologic features associated with progression-free interval (PFI) that was dichotomized based on an optimized cutpoint for distinguishing PFI into a high risk CHAI (+) and lower risk CHAI (-). PFI was compared between CHAI (+) and CHAI (-) patients in the validation cohort in multivariable Cox proportional hazards models. Time-dependent area under the curve (tdAUC) and C-indices were also calculated for PFI. RESULTS: A total of 583 participants were included in the study, with 409 assigned to the validation cohort. The CHAI biomarker classified 229 participants (56%) as CHAI (+) and 180 (44%) as CHAI (-) in the validation set. CHAI (+) participants had worse PFI in a multivariable analysis adjusting for available clinicopathologic variables (hazard ratio (HR) = 2.65; 95% confidence interval (CI), 1.63-4.30). TdAUC for the CHAI biomarker was 0.60 (95% CI, 0.53-0.67) at 12 months, 0.62 (0.55-0.69) at 36 months, and 0.67 (0.55-0.79) at 60 months; the C-index was 0.62 (95% CI, 0.58-0.67). CONCLUSIONS: The CHAI platform was used to develop a prognostic digital pathology biomarker in CRC. This demonstrates the feasibility and potential to apply this artificial intelligence-based digital pathology biomarker platform for risk stratification in CRC and supports its further study.

Artificial intelligence↗

PubMedDate not supplied

Cytometric prognostic parameters in breast cancer.

Prognostic parameters were examined in a retrospective survey of 730 cases of overt distant metastasis-free invasive breast cancer. A multivariate combination of cytometric and clinical parameters allowed the stratification of patients into five prognostic categories. In the low-risk group the distant recurrence rate was only 3.3%, In the highest risk group 57%. We conclude that cytometric parameters can increase the precision of prognostic evaluation in invasive breast cancers, and thus aid in decisions.

Adult↗

PubMed2001

Proteins expressed in osteosarcoma and serum levels as prognostic factors.

Osteosarcoma is the most frequent highly malignant bone-tumor with a peak manifestation during the second and third decade of life. Although survival rate increased up to 60-70% within the last 20 years, the problem of non-response to chemotherapy remains. Initial tumor size and response to neoadjuvant chemotherapy are the most accepted prognostic factors used for postoperative stratification of chemotherapy. The identification of patients with a bad response to therapy at the time of diagnosis would facilitate already a preoperative stratification of chemotherapy or a more aggressive regime to increase survival. This review reflects on recently described molecular markers but not on clinical parameters in human osteosarcoma with respect to their prognostic potential. This includes p53, the p-glycoprotein, the multidrug resistance gene, the humen epidermal growth factor receptor and metallothionein expression. Heat shock proteins have recently become important in osteosarcoma because of their prognostic value and their role in drug resistance. A short overview of serological markers is also given. Further results on drug resistance and survival may be provided by ongoing studies, which investigate the role of proteins of the apoptotic and antiapoptotic families in human osteosarcoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

Prognostic factors for survival of patients with glioblastoma: recursive partitioning analysis.

Survival for patients with glioblastoma multiforme is short, and current treatments provide limited benefit. Therefore, there is interest in conducting phase 2 trials of experimental treatments in newly diagnosed patients. However, this requires historical data with which to compare the experimental therapies. Knowledge of prognostic markers would also allow stratification into risk groups for phase 3 randomized trials. In this retrospective study of 832 glioblastoma multiforme patients enrolled into prospective clinical trials at the time of initial diagnosis, we evaluated several potential prognostic markers for survival to establish risk groups. Analyses were done using both Cox proportional hazards modeling and recursive partitioning analyses. Initially, patients from 8 clinical trials, 6 of which included adjuvant chemotherapy, were included. Subsequent analyses excluded trials with interstitial brachytherapy, and finally included only nonbrachytherapy trials with planned adjuvant chemotherapy. The initial analysis defined 4 risk groups. The 2 lower risk groups included patients under the age of 40, the lowest risk group being young patients with tumor in the frontal lobe only. An intermediate-risk group included patients with Karnofsky performance status (KPS) >70, subtotal or total resection, and age between 40 and 65. The highest risk group included all patients over 65 and patients between 40 and 65 with either KPS<80 or biopsy only. Subgroup analyses indicated that inclusion of adjuvant chemotherapy provides an increase in survival, although that improvement tends to be minimal for patients over age 65, for patients over age 40 with KPS less than 80, and for those treated with brachytherapy.

Adult↗

PubMed2005

Tissue inhibitor of metalloproteinases-1 in breast cancer.

Whether patients diagnosed with primary breast cancer are offered adjuvant systemic therapy following surgical removal of the tumor is based on prognosis. Prognosis is estimated in every patient using established prognostic variables. Unfortunately, when using the currently available prognostic parameters a significant proportion of patients are over-treated. Thus, in order to improve stratification of breast cancer patients, additional prognostic factors need to be identified. Tissue inhibitor of metalloproteinases-1 (TIMP-1) is one of the promising candidates for new prognostic markers in breast cancer, as a number of studies have demonstrated an association between high tumor-tissue levels of TIMP-1 mRNA as well as TIMP-1 protein and a poor prognosis of breast cancer patients. TIMP-1 is a member of the TIMP family, currently comprising four members (TIMP-1-4), and its main function is inhibition of the activity of various matrix metalloproteinases (MMPs). The association between high levels of protease inhibitor and poor prognosis may be somewhat surprising, as proteolytic activity plays a pivotal role in cancer cell invasion and metastasis. However, the recent discovery of other biological functions of TIMP-1 such as growth-stimulating functions, as well as anti-apoptotic and pro-angiogenetic effects, may in part explain this paradox. The purpose of this review is to give an update on the current status of TIMP-1 in breast cancer, emphasizing the prognostic utility of the inhibitor. In addition, the suggested tumor-stimulatory roles of TIMP-1 will be outlined.

Biomarkers, Tumor↗

PubMedDate not supplied

Risk stratification in the elderly patient after coronary artery bypass grafting: the prognostic value of radionuclide cineangiography.

BACKGROUND: Recent data have shown that assessment of left ventricular function by radionuclide cineangiography (RNCA) predicts survival and cardiac events among non-age-selected patients who have previously undergone coronary artery bypass grafting (CABG). However, the prognostic value of this noninvasive approach is not known for elderly patients who now undergo CABG with progressively increasing frequency and who survive longer because of operation. Such easily applied prognostic indexes may be useful to determine whether survival benefits are likely to be maintained or additional therapy should be considered. METHODS AND RESULTS: To obtain information on factors related to long-term survival and cardiac events among elderly patients after CABG and, specifically, to determine the prognostic implications of left ventricular performance at rest and during exercise for predicting all causes of death, major nonsurgical cardiac events (death or myocardial infarction), and event-free or surgery-free survival, we evaluated the late postoperative course of 41 patients, aged 65 years and older, who had undergone RNCA 1 month or more (mean 2.3 +/- 2.4 years; range 0.1 to 9 years) after CABG. Average follow-up among patients with event-free survival was 8.8 years after index radionuclide assessment. During follow-up 13 patients died with no known intercurrent event, five patients had nonfatal myocardial infarctions, and five underwent late (> or = 3 months after RNCA) repeat CABG or percutaneous transluminal coronary angioplasty. Log-rank comparisons of Kaplan-Meier product limit estimate curves identified only left ventricular ejection fraction at rest as significantly predictive of survival (p < 0.04). Patients with left ventricular ejection fraction at rest of less than 45% had a 7.8% average annual mortality risk, which was more than three times that of patients with normal resting function. Statistical trends also were found between mortality rates and completeness of revascularization (p < 0.06), major nonsurgical cardiac events and extent of anatomic disease (p < 0.08), and event-free or surgery-free survival and our index of completeness of revascularization (p = 0.08) and age at index RNCA (p < 0.07). CONCLUSIONS: Assessment of left ventricular ejection fraction at rest is prognostically useful after CABG among elderly patients. The efficacy and timing of this approach should be confirmed in further investigations with larger and more varied patient subgroups.

Aged↗

PubMed1999

[Noninvasive risk stratification of patients with unstable angina in the acute phase. The prognostic value of exercise and stress after drug treatment].

Most of the prognostic information on patients with unstable angina is obtained from the initial clinical assessment and the patient's subsequent course over the first few days of management. In recently stabilized patients noninvasive stress testing with exercise or pharmacologic testing provide additional useful risk assessment. Noninvasive stress testing should be part of the outpatient evaluation of low-risk patients with unstable angina and should be done within 72 hours. Unless cardiac catheterization is indicated, noninvasive stress testing should be performed in low- or intermediate-risk patients hospitalized with unstable angina who have been free of symptoms for a minimum of 48 hours. Choice of stress testing modality should be based on an evaluation of the patient's resting ECG, his or her physical ability to perform exercise, and the local expertise and technologies available. The standard ECG treadmill test should be the standard test employed in most patients with no contraindications for doing so. Provocation of ischemia at a low workload (< 5 to 6 METs) signifies a high-risk patient (cardiac mortality > or = 4%/year) who should generally merit referral to cardiac catheterization. Attainment of a higher workload (> 5 to 6 METs) without ischemia is associated with a better prognosis (cardiac mortality < 1%/year), and many such patients can be managed conservatively. Those who tolerate only a low workload but have no evident ischemia or those who develop ischemia at a high workload, represent an intermediate-risk group (cardiac mortality 2 to 3%/year) for whom several reasonable strategies can be proposed.

Acute Disease↗

PubMed1992

[Risk stratification in patients recuperating from acute myocardial infarct. How useful is it?].

The author intended to discuss the individual prognostic value of some best known risk stratification variables after Acute Myocardial Infarction (AMI), whose tests have a low diagnostic accuracy due to high risk individual variations, emphasizing the statistic errors of using one single risk variable on post AMI risk stratification schemes. Some epidemiologic data about AMI survivors are reviewed and the author concludes by emphasizing the importance of using more AMI population characteristics on post AMI risk stratification schemes.

Arrhythmias, Cardiac↗

PubMed2000

The impact of covariate imbalance on the size of the logrank test in randomized clinical trials.

This paper examines the baseline imbalance incidental to stratified random sampling in clinical trials. We assume that patients are randomly sampled from a stratum-specific population and assigned to either treatment or control groups. Prognostic factors not used for the stratification cause within-stratum patient heterogeneity. The patient heterogeneity is investigated with an analysis of the prognostic index, or the log-relative-hazard. An index V, used to measure the degree of baseline imbalance between the groups, is defined using the prognostic index. The degree of baseline imbalance resulting from the stratified random sampling of a population of heterogeneous patients is examined. A method to estimate the exact size of the stratified logrank test is developed and applied to data obtained from a cancer clinical trial.

Adult↗