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PubMed1982

[Value of quantitative electroencephalography in psychiatry].

Computerized quantitative EEG processes the signal in four sequential steps: 1) EEG sampling with rejection of artefacts; 2) Fourier analysis (power spectrum according to frequency); 3) data reduction with computation of spectral parameters in five-minute recordings on at least four EEG channels (mean frequencies, mean amplitudes in microvolts and %, with standard deviations for delta, theta, alpha and beta frequency bands); 4) data base and multivariate statistical analyses. Five main results are obtained by computerized quantitative EEG analysis in psychiatry and clinical pharmacology: 1) longitudinal studies of patients before and after treatment; 2) transversal studies of homogeneous EEG groups (discrimination between tracings of residual-type or paranoid-type schizophrenic patients) comparatively with control groups (high and low alpha subjects); 3) study of psychotropic drugs: profiles, prediction of action, dose-effect curves, pharmacokinetic studies, biodisponibility, correlations with plasmatic levels and behavioural or clinical psychiatric rating scales; 4) typologic classification and discrimination by multivariate analysis, studies of functional activities: functional interhemispheric lateralisation of amplitudes and its variations during the course of psychotic processes; 5) new techniques: computerized topo-electroencephalography (CT-EEG, BEAM technique) based on 16 EEG recordings, comparison with other imaging techniques.

Computers↗
PubMed1990

Gas chromatographic characterization of the relationship between some Mycobacterium avium and Mycobacterium paratuberculosis strains.

Mycobacterium avium strain P-55 and M. avium strain DENT differ from M. avium strain 16909-338 on the basis of their fatty acid spectra (C14:0, C18:0 and tuberculostearic [TBS] acids) studied by multivariate statistical analyses. Strains P-55 and DENT are closer to M. paratuberculosis strain 5889 than to M. avium strain 16909-338, a finding which is in harmony with earlier immunological observations. The recently isolated M. paratuberculosis strain 385 has proved different from M. paratuberculosis strain 5889.

Animals↗
PubMed2001

To move or not to move: measurements of prostate motion by urethrography using MRI.

PURPOSE: Urethrography is commonly used to aid in definition of the prostate apex during CT simulation for prostate cancer. If the position of the prostate were altered by the urethrogram itself, then systematic error could be introduced into the patient's treatment. Sagittal MRI scans were acquired immediately before and after a localization urethrogram to determine the extent of displacement. METHODS AND MATERIALS: Thirteen patients underwent sagittal T2-weighted fast spin echo MRI scans. Patients were scanned supine in an alpha cradle cast in the treatment position. The prostate was contoured by 3 different observers to determine the apex location on the central sagittal MRI section and the center of mass relative to an immobile bony landmark. Statistical multivariate analysis was performed to establish if there was a net displacement of the prostate (systematic error), and to determine the margin required to cover the random prostate position within a 95% confidence interval. RESULTS: There was no significant systematic motion of either the prostate nor its apex in either the anterior-posterior or superior-inferior directions. The average motion of the prostate center of mass was 0.04 +/- 0.40 cm (1 SD) and 0.01 +/- 0.33 cm in the anterior-posterior and superior-inferior direction, respectively. The corresponding figures for location of the apex were 0.05 +/- 0.30 cm and 0.01 +/- 0.33 cm, respectively. The statistical analysis revealed that a margin of 2 mm is sufficient to cover any random motion of the prostate that could occur as a result of the urethrogram 95% of the time. CONCLUSION: Urethrography during CT simulation for prostate cancer does not cause significant prostate displacement or systematic error in planning and delivering external-beam radiation.

Adenocarcinoma↗
PubMed1985

Clinical relevance of lymphoblast biological features in children with acute lymphoblastic leukemia.

Improvements in therapy for childhood acute lymphoblastic leukemia (ALL) have led us to reevaluate the prognostic significance of lymphoblast characteristics at diagnosis. From application of univariate and multivariate statistical methods, we determined the relationship of five blast cell features to treatment outcome in 250 patients who were enrolled in two clinical trials at this center from May 1979 through April 1982. Karyotype ploidy, lymphoblast morphology, and immunophenotype were each significantly related to prognosis as measured by time to failure, while periodic acid-Schiff reactivity and glucocorticoid receptor number lacked prognostic implication for this patient population. In addition, clinical features of initial WBC count, age, and race were also significant independent variables in predicting treatment response. By multivariate analysis, both ploidy and morphology contributed prognostic information to a clinical model based on WBC count, age, and race. If the model was adjusted for impact of ploidy, however, French-American-British morphology no longer contributed additional prognostic information. Our findings suggest that many traditional biological features used to estimate prognosis in ALL can be discarded in favor of clinical features (leukocyte count, age, and race) and cytogenetics (ploidy) for planning of future clinical trials.

Adolescent↗
PubMed1997

Effect of infarct-related artery patency and late potentials on late mortality after acute myocardial infarction.

OBJECTIVE: To assess the effect of patency of the infarct-related artery and the presence of late potentials on late cardiac mortality after myocardial infarction. MATERIAL AND METHODS: We studied the influence of the infarct-related artery patency and the presence of late potentials during signal-averaged electrocardiography on late mortality in 124 survivors of acute myocardial infarction. In addition, we assessed predictive factors of cardiac mortality by univariate and multivariate statistical analysis. RESULTS: A study group of 98 men and 26 women (mean age, 59 years) who were survivors of acute myocardial infarction underwent follow-up for a mean of 3.6 +/- 1.0 years. Immediate reperfusion therapy (thrombolysis or direct angioplasty) was accomplished in 71 patients (57%). During follow-up, 13 cardiac-associated deaths occurred. Infarct-related artery patency was strongly associated with improved survival, but the presence of late potentials did not correlate with increased mortality, even among patients with impaired left ventricular function. Univariate and multivariate analyses identified occluded infarct-related arteries, prior myocardial infarction, reduced left ventricular ejection fraction, and advanced age, but not late potentials, as predictors of increased late cardiac mortality. CONCLUSION: These data suggest that coronary angiography may, but signal-averaged electrocardiography may not, identify patients with increased late risk of cardiac-related death after myocardial infarction. The low mortality among patients who have undergone successful reperfusion therapy may reduce the ability of noninvasive tests to distinguish between high- and low-risk patients.

Analysis of Variance↗
PubMed1991

The distribution of lung cancer mortality in Cape Town and related factors.

Lung cancer, a disease which primarily occurs in urban areas, caused 1,130 deaths during 1984-1986 in Cape Town. It is the most prevalent cause of cancer death in men and is second only to breast cancer in women. It was responsible for 22.9% of all cancer deaths in Cape Town during the 3-year period. The cartographic representation of standardised mortality ratios shows that the incidence of lung cancer mortality in Cape Town is appreciably higher in men than women, and in coloured people than in white people. Coloured men are the group most at risk. Despite the important role smoking habits play in the aetiology of lung cancer, the results of the ecological analyses show that environmental factors are partly responsible for the incidence of the disease. In the case of white people demographic as well as socioeconomic variables, such as age, home language, religious affiliation and level of education, were identified by the multivariate statistical techniques as associated variables. In the case of coloured people the factors that play a role are chiefly socio-economic ones, such as unemployment, home owner status and type of housing. Positive relationship with low socio-economic status pertains only to coloured people.

Black or African American↗
PubMed1993

Analysis of the biological and molecular properties of phencyclidine-like compounds by chemometrics.

The quantitative structure-activity relationships (QSAR's) of 3 series of arylcyclohexylamines have been investigated using computational chemistry and multivariate statistics. Principal component analysis of the aromatic ring data set demonstrated some clustering of activity categories. Biological activity of the cyclohexane ring data set was correlated with molar refractivity. These findings may be useful for predicting the activity of novel neuroprotective agents.

Cyclohexanes↗
PubMed2002

Risk stratification applied to CAST registry data: combining 9 predictors. Cardiac Arrhythmia Suppression Trial.

Over 200,000 people in the United States die of sudden cardiac death (SCD) every year. Although many of these deaths occur in asymptomatic individuals, the vast majority of deaths occur in people who are under care for existing coronary heart disease. Implantable cardioverter/defibrillators (ICDs) have been shown in several randomized trials to be effective in prolonging lives of those at high risk for sudden cardiac death, but the criteria used in these trials and the ACC/AHA consensus guidelines would cover only a minority of patients. Developing methods to assign risk to individual patients without prior SCD events could promote the use of this life-saving therapy in those with especially high risk. Given sufficient physiologically relevant measurements from electrocardiogram analysis, clinical assessment, and demographic status, multivariate statistical methods for predicting survival can be used to combine many predictors of risk and calculate the risk for an individual patient. A survival analysis using Cox regression on data from the Cardiac Arrhythmia Suppression Trial (CAST) illustrates this concept. Patient age, sex, ejection fraction, smoking history, and prior myocardial infarction history, along with the frequency of premature beats and the presence of runs of ventricular tachycardia on Holter monitoring and the time from the index myocardial infarction to the baseline Holter and to recruitment into CAST were combined in a multivariate predictor derived from the Cox regression; this predictor significantly outperforms the individual predictors. A proposed test based on this predictor would identify as positive 7% of the CAST registry, with an average risk of death among the positives of 47%; 20% of those dead at 2 years would be positive. With improved component measurements, this approach has the potential for significantly improving risk stratification for the prevention of SCD.

Age Factors↗
PubMed2004

Genes@Work: an efficient algorithm for pattern discovery and multivariate feature selection in gene expression data.

MOTIVATION: Despite the growing literature devoted to finding differentially expressed genes in assays probing different tissues types, little attention has been paid to the combinatorial nature of feature selection inherent to large, high-dimensional gene expression datasets. New flexible data analysis approaches capable of searching relevant subgroups of genes and experiments are needed to understand multivariate associations of gene expression patterns with observed phenotypes. RESULTS: We present in detail a deterministic algorithm to discover patterns of multivariate gene associations in gene expression data. The patterns discovered are differential with respect to a control dataset. The algorithm is exhaustive and efficient, reporting all existent patterns that fit a given input parameter set while avoiding enumeration of the entire pattern space. The value of the pattern discovery approach is demonstrated by finding a set of genes that differentiate between two types of lymphoma. Moreover, these genes are found to behave consistently in an independent dataset produced in a different laboratory using different arrays, thus validating the genes selected using our algorithm. We show that the genes deemed significant in terms of their multivariate statistics will be missed using other methods. AVAILABILITY: Our set of pattern discovery algorithms including a user interface is distributed as a package called Genes@Work. This package is freely available to non-commercial users and can be downloaded from our website (http://www.research.ibm.com/FunGen).

Algorithms↗
PubMed2000

Confocal laser scanning ophthalmoscope and spherical harmonics used as a possible aid to detect glaucoma.

We present a procedure whereby the confocal laser scanning ophthalmoscope can be used to extract information about the three-dimensional structure of the central excavated area or the cup of the optic nerve head of the eye. The data are analyzed in terms of spherical harmonics. It is hypothesized that the shape of the cup of the optic nerve head for a normal eye can be parameterized by a specific set of spherical harmonic coefficients and is different from the set of coefficients describing a glaucomatous eye. The sets of coefficients are analyzed by using multivariate statistics and can in turn be used to classify new observations. Preliminary results indicate that there are significant differences in the coefficients and that the procedure might have potential as a diagnostic aid for the detection or the screening of glaucoma.

Glaucoma↗
PubMed2003

Sequencing radiotherapy for soft tissue sarcoma when re-resection is planned.

PURPOSE: To evaluate whether disease outcome for localized soft-tissue sarcoma (STS) excised before referral to a specialist center and there re-resected was influenced by the timing of radiation therapy (XRT)-before or after re-resection. MATERIALS AND METHODS: Two hundred ninety-five consecutive patients with localized grossly excised STS were retrospectively evaluated for local control, freedom from metastasis, disease-free survival, and disease-specific survival, according to whether they had XRT before (121) or after (174) re-resection of their tumor bed. Univariate and multivariate statistical techniques were employed. RESULTS: At re-resection, residual STS was found in 159 patients (54%), including gross tumor in 73 (25%). The incidence of residual disease was lower in those receiving preoperative XRT (median dose 50 Gy) (36%) than in those having postoperative RT (median dose 60 Gy) (54%) (p = 0.024). With a median follow-up of 9.1 years, the local control rates for all patients at 5, 10, and 15 years were 86%, 84%, and 81%, respectively, and there were no differences between the two XRT sequences. In multivariate regression, there was no evidence that XRT sequence influenced local control, metastatic control, disease-free survival, or disease-specific survival. There was a trend toward fewer XRT-related late complications with preoperative XRT, but this was not significant, and the incidence of complications was low (5% at 15 years). CONCLUSIONS: Patients who present after total but oncologically inadequate excision of STS can receive approximately 50 Gy before re-resection or approximately 60 Gy after re-resection, with approximately equivalent, satisfactory local control and overall disease outcome. Decisions as to the most appropriate treatment sequence for any individual patient can be made regardless of considerations as to the effectiveness of one sequence compared with the other.

Adolescent↗
PubMed1990

The significance of erythrocyte sedimentation rate as a prognostic factor for patients with prostate cancer: Gunma Urological Oncology Study Group investigation.

The Gunma Urological Oncology Study Group has performed a multivariate statistical analysis of prognostic factors based on 353 patients with prostate cancer diagnosed between 1974 and 1984. This paper discusses the prognostic significance of erythrocyte sedimentation rate (ESR) in these patients with prostate cancer. Based on three ranges (less than 20, greater than 20- less than 50, greater than 50 mm/h) of ESR, a significant difference of survival rates among the patients was found by means of univariate analysis. ESR apparently includes components which represent anemia or infection. Hemoglobin, frequently used as a prognostic factor, was compared with ESR by means of multivariate analysis, and ESR was found to be a more useful prognostic factor than hemoglobin. Moreover ESR showed the highest partial coefficient value among the items studied (clinical stage, pathological differentiation, age, acid phosphatase, gait disturbance). It seems that ESR includes not only anemia and infection components but also provides a clue to the degree of bone metastasis or the degree of prostate cancer progression.

Acid Phosphatase↗
PubMed1986

Effects of neuroleptic drugs on the inhibition of exploratory behaviour induced by a low dose of apomorphine: implications for the identity of dopamine receptors.

Apomorphine in low doses inhibits spontaneous exploratory behaviour in rats. This effect is commonly referred to as an expression of selective stimulation of dopaminergic autoreceptors. The aim of the present study was to investigate the influence of neuroleptic drugs with different pharmacological profiles on this apomorphine induced inhibition of exploration using techniques for detailed recording of behaviour and multivariate statistical analysis of the results. By comparison with dose response analyses of apomorphine it was possible to determine whether a neuroleptic specifically antagonised the apomorphine effect or if the pattern of behaviour was qualitatively changed in some way. Apomorphine (0.05 mg/kg) was tested against cis-flupenthixol (0.01-0.5 mg/kg), haloperidol (0.01-0.1 mg/kg), metoclopramide (0.2-5 mg-kg), sulpiride (0.5-50 mg/kg) and SCH 23390 (0.005-0.05 mg/kg). Metoclopramide and haloperidol had weak antagonising effects against apomorphine while cis-flupenthixol and SCH 23390 was completely inefficient in this respect. The multivariate analysis indicated that the effects of haloperidol was restricted to only some aspects of the behavioural effects of apomorphine. Only sulpiride did selectively and dose-dependently antagonise the apomorphine induced behavioural suppression. The data provide evidence for a functional subdivision of dopamine receptors at the behavioural level.

Animals↗
PubMed2004

Economic benefit from clinical practice guideline compliance in stroke patient management.

BACKGROUND AND PURPOSE: In a previous study we showed that compliance with evidence-based guidelines improves the health outcome of stroke patients in terms of both survival and residual disability. In this analysis, we shall investigate the impact of such guidelines on healthcare costs during the acute/sub-acute hospitalisation phase. METHOD: we considered the direct costs from the hospital's point of view, where funding is provided by the National Healthcare System. We did not consider production loss or intangible costs related to the decreased quality of life. Data was collected on both costs and guideline compliance prospectively, and the relationship between them was studied through a multivariate statistical model. RESULTS: Patients treated according to guidelines result in lower costs; on average they have a shorter length of stay in hospital (10.8 versus 12.9 days), leading to a significant difference in the consumption of hospital resources. On a level of statistical analysis, guideline compliance is a significant independent indicator of cost, together with the patient's initial disability and neurological deficit.

Aged↗
PubMed2003

[Factors of importance for early and late admission of patients with stroke and transient cerebral ischemia].

INTRODUCTION: Early admission after stroke and TIA is important in modern stroke treatment. We studied the time delay to admission and explored predictive factors of early/late admission. MATERIAL AND METHODS: The study was prospective and community-based comprising all patients with stroke or TIA admitted to a Copenhagen hospital from 1 September 1999 to 30 April 2000. The catchment area is well defined with 283,000 inhabitants. All had a neurological examination and a structured interview within three days with registration of age, gender, premorbid Rankin, Scandinavian stroke scale score, time of onset, knowledge of the cause of symptoms, cohabitation, alone at onset, whether admitted by a general practitioner (GP) or by ambulance after calling emergency, and relevant stroke risk factors. Univariate and multivariate statistics were used. RESULTS: Altogether 494 patients with stroke and 63 with TIA were entered; 49% were admitted by a GP, 38% by ambulance after calling emergency, 13% via other routes. Time from onset to hospital admission could be assessed reliably in 374 patients (67%) and was a median of 2.6 hours; 37% arrived within 0-3 hours, 55% within 0-6 hours. Patients calling an ambulance over emergency arrived at a median of 1.0 hour after the stroke; those calling the GP a median of 6.0 hours after the stroke. In a multivariate analysis only admission by ambulance after calling emergency (OR 5.7), TIA (OR 5.6), or the patient's knowledge of the cause of the symptoms (OR 2.2) were predictors of early admission. DISCUSSION: Patients with stroke or TIA in a Danish metropolitan area arrive at hospital a median of 2.6 hours after the stroke. Admission by ambulance after calling emergency was associated with the shortest onset to admission time.

Aged↗
PubMed1976

"Prediction" of the one-minute Apgar score from fetal heart rate data.

The value of any fetal monitoring technic is in its ability to predict infant outcome. In the present study, the ability of fetal heart rate (FHR) monitoring data to "predict" a measure of short-term infant outcome, the 1-minute Apgar score, was evaluated using univariate and multivariate statistical analyses. Of 61 monitored high-risk infants, 46 had high (7 to 10) and 15 had low (1 to 6) 1-minute Apgar scores. Computer analysis of FHR/intrauterine pressure (IUP) data for these 61 infants revealed that the infants with low Apgar scores had more than the expected number of late decelerations (LD). Using a threshold of ten LD and univariate analysis, 74% of the infants could be properly classified for high or low Apgar scores, but 60% of the infants with low Apgar scores were not identified. Using discriminant function (multivariate) analysis for the numbers of LD and uterine contractions, 47% of the depressed infants were appropriately identified and simple risk scoring equations were devised. Using additional observation vectors, including the number of accelerations and early decelerations, 67% of the depressed infants could be identified. The results of this study suggest that using multiple observation vectors improves the predictive capacity and, thus, the value of fetal monitoring data. Clinical experience suggests that the value of monitoring data can be further enhanced by simultaneous evaluation of other observation vectors from additional perinatal data sets using the technics of this study.

Analysis of Variance↗
PubMed1983

Multiple observers, humidity, and choice of precision statistics: factors influencing craniometric data quality.

This study investigates three topics: (1) interobserver measurement error in craniometry, (2) the effects of humidity on craniometric measurements, and (3) the current status of estimators of measurement precision in craniometry and anthropometry. The results of the three-observer error analysis based on 24 linear measurements taken on 47 crania indicate that minor idiosyncratic variations in measurement technique can lead to high levels of statistical discrimination among the data produced by the different observers. The results of the humidity experiment substantiate the contention that increasing levels of relative humidity are associated with cranial expansion. The results of the comparison of 11 univariate precision estimators suggest that the combination of percentage agreement, the mean absolute difference, and Fisher's nonparametric sign test can give an instructive picture of the frequency, magnitude, and directionality of measurement imprecision. Information on the comparability of technique and measurement precision can then be used in the variable selection process prior to the application of multivariate statistical procedures to strengthen the substantive interpretation of craniometric data.

Analysis of Variance↗
PubMed2005

Identification of neutrophil gelatinase-associated lipocalin (NGAL) as a discriminatory marker of the hepatocyte-secreted protein response to IL-1beta: a proteomic analysis.

The liver is the major source of proteins used throughout the body for various functions. Upon injury or infection, an acute phase response (APR) is initiated in the liver that is primarily mediated by inflammatory cytokines such as interleukin-1beta (IL-1beta) and interleukin-6. Among others, the APR is characterized by an altered protein synthetic profile. We used two-dimensional gel electrophoresis to study the dynamics of changes in protein synthesis in hepatocytes exposed to these inflammatory cytokines. Protein profiles were quantified using image analysis and further analyzed using multivariate statistical methods. Our results indicate that IL-1beta and IL-6 each induces secreted protein responses with distinct dynamics and dose-dependence. Parallel stimulation by IL-1beta and IL-6 results in a protein pattern indistinguishable from the IL-1beta pattern, indicating a dominant effect of IL-1beta over IL-6 at the doses tested. Multidimensional scaling (MDS) of correlation distances between protein secretion levels revealed two protein pairs that are robustly co-secreted across the various cytokine stimulation conditions, suggesting shared regulatory pathways. Finally, we also used multivariate alternating conditional expectation (MACE) to identify transformation functions that discriminated the cytokine-stimulated and untreated hepatocyte-secreted protein profiles. Our analysis indicates that the expression of neutrophil gelatinase-associated lipocalin (NGAL) was sufficient to discriminate between IL-1beta and IL-6 stimulation. The combination of proteomics and multivariate analysis is expected to provide new information on the cellular regulatory networks involved in generating specific cellular responses.

Acute-Phase Proteins↗