SEARCH · PubMed Health

Results for “multivariate analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 847 records · Page 47Linked to original sources

PubMed1984

Multivariate analysis of prognostic factors for operable rectal cancer.

Previous reports have established that several variables are of prognostic importance in rectal cancer. The information from a Medical Research Council trial in seventeen centres in the United Kingdom was used to assess the simultaneous contribution of several of these factors in a multivariate analysis. In the preoperative assessment mobility of the tumour and the number of quadrants involved were predictive of the likelihood of a curative resection being possible. Among patients who had curative resections, prognosis was influenced by Dukes' classification, height of tumour, histological grade, and venous invasion. A scoring system based on these criteria was constructed and applied to this group of patients. It successfully defined five prognostic groups with 5-year survival rates ranging from 80% to 19%.

Adult↗

PubMed1978

Prognostic factors in cutaneous malignant melanoma in stage I. A clinical, morphological and multivariate analysis.

In a retrospective study of 324 cutaneous malignant melanomas in stage I, treated during the years 1959-74, the influence of different morphological and clinical factors on the prognosis was investigated. 223 patients with melanoma in levels II-V, observed for more than five years, were subjected to a multivariate analysis. 180/223 were in levels III-V. The age of the patient, the location of the tumour, its diameter, thickness, infiltration level, presence of ulceration and mitotic activity were shown to be of significant importance for the five-year survival of the 223 patients. Analysis limited to levels III-V disclosed that the diameter and the thickness of the tumour but not the infiltration level significantly influenced the prognosis. However, the sex of the patient, the histogenetic type of the tumour, the cross-sectional profile, vascular invasion and degree of lymphocytic infiltration did not correlate with survival.

Adult↗

PubMed1983

Enhanced evaluation of treadmill tests by means of scoring based on multivariate analysis and its clinical application: a study of 608 patients.

Six hundred eight patients being evaluated for chest pain who did not have valvular disease, cardiomyopathy, left ventricular hypertrophy or bundle branch block, and were not receiving digitalis, had treadmill tests and coronary angiograms. In 351, various exercise variables were correlated by multivariate analysis to coronary artery disease (CAD). In men, significant variables were: (1) maximal heart rate achieved less than 80% of maximal predicted heart rate (Mx PHR), (2) ST-T change greater than or equal to 1 mm, (3) age greater than or equal to 55 years and (4) treadmill time (TT) less than 8 minutes. These variables rated diagnostic scores of 9, 6, 5, and 3, respectively. A score of greater than or equal to 7 was considered diagnostic of CAD. In a test group of 192 men in which ST-T change was compared with treadmill score, sensitivity was 65 versus 85%, specificity 79 versus 74% and accuracy 69 versus 83%. In women, maximal heart rate less than 90% of Mx PHR and TT of less than 6 minutes were significant, with an accuracy of 75%. Moreover, 89% of incomplete tests and 70% of tests in patients with previous myocardial infarction were also correctly diagnosed. This method allows convenient use of significant exercise variables for clinical purposes with improved results.

Adult↗

PubMed1999

Sediments as monitors of heavy metal contamination in the Ave river basin (Portugal): multivariate analysis of data.

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) were determined in river sediments collected at the Ave river basin (Portugal) to obtain a general classification scenery of the pollution in this highly polluted region. Multivariate data analysis techniques of clustering, principal components and eigenvector projections were used in this classification. Five general areas with different polluting characteristics were detected and several individual heavy metal concentration abnormalities were detected in restricted areas. A good correlation between the overall metal contamination determined by multivariate analysis and metal pollution indexes for all sampling stations was obtained. Some preliminary experiments showed that the metal concentrations normalised to the volatile matter content in the sediment fraction with grain size <63 microm seems to be an adequate method for assessing metal pollution.

Journal Article↗

PubMed2005

Multivariate analysis of TOF-SIMS spectra of monolayers on scribed silicon.

Static time-of-flight secondary ion mass spectrometry (TOF-SIMS) was performed on monolayers on scribed silicon (Si(scr)) derived from 1-alkenes, 1-alkynes, 1-holoalkanes, aldehydes, and acid chlorides. To rapidly determine the variation in the data without introducing user bias, a multivariate analysis was performed. First, principal components analysis (PCA) was done on data obtained from silicon scribed with homologous series of aldehydes and acid chlorides. For this study, the positive ion spectra, the negative ion spectra, and the concatentated (linked) positive and negative ion spectra were preprocessed by normalization, mean centering, and autoscaling. The mean centered data consistently showed the best correlations between the scores on PC1 and the number of carbon atoms in the adsorbate. These correlations were not as strong for the normalized and autoscaled data. After reviewing these methods, it was concluded that mean centering is the best preprocessing method for TOF-SIMS spectra of monolayers on Si(scr). A PCA analysis of all of the positive ion spectra revealed a good correlation between the number of carbon atoms in all of the adsorbates and the scores on PC1. PCA of all of the negative ion spectra and the concatenated positive and negative ion spectra showed a correlation based on the number of carbon atoms in the adsorbate and the class of the adsorbate. These results imply that the positive ion spectra are most sensitive to monolayer thickness, while the negative ion spectra are sensitive to the nature of the substrate-monolayer interface and the monolayer thickness. Loadings show an inverse relationship between (inorganic) fragments that are expected from the substrate and (organic) fragments expected from the monolayer. Multivariate peak intensity ratios were derived. It is also suggested that PCA can be used to detect outlier surfaces. Partial least squares showed a strong correlation between the number of carbon atoms in the adsorbate and the number it predicted.

Journal Article↗

PubMed1980

Multivariate analysis of risk factors for stroke. Eight-year follow-up study of farming villages in Akita, Japan.

Akita Prefecture has an especially high mortality rate from stroke, and its age-adjusted death rate from stroke is the highest in Japan. We have carried out an epidemiological survey of cardio- and cerebrovascular diseases (CVD) in farming villages in this prefecture since 1963, with a response rate of 84%. During our 8-year follow-up, 94 new stroke cases were observed among 1,814 subjects. Multiple logistic function analysis was carried out on nonstroke and stroke cases from subjects aged 40 to 69 years at time of initial examination, in order to clarify the risk factors for stroke. The analysis used eight variables: age, sex, systolic blood pressure, obesity index, urinary sugar, urinary protein, serum total cholesterol, and total protein. The results showed that hypertension was the most important risk factor for stroke. However, regarding cholesterol, multivariate analysis showed that among men and women aged 40 to 69 years at entry, subjects with low serum total cholesterol levels were more prone to cerebral hemorrhage, but that serum cholesterol level had no weight as a risk factor for cerebral infarction. These results correspond well with the observed fact that stroke incidence or death rate in Japan is higher in populations with high prevalence of hypertension and low concentration of cholesterol, and also with the fact that death rate from hemorrhage declines with the increment of serum total cholesterol and the westernization of diet.

Adult↗

PubMed2002

Multivariate analysis of risk factors for hospital mortality in valvular reoperations for prosthetic valve dysfunction.

OBJECTIVES: The purpose of the study was to analyze risk factors for hospital mortality in patients undergoing valvular reoperations for prosthetic valve dysfunction. METHODS: We performed a prospective analysis of 146 patients who underwent valvular reoperations for prosthetic valve dysfunction between July 1995 and June 1999 at the Heart Institute of the University of São Paulo Medical School. Multivariate statistical analysis with logistic regression was used to analyze preoperative and intraoperative variables to determine risk factors for hospital mortality. RESULTS: The overall hospital mortality was 10.9% (16 patients). Univariate analysis showed that the following variables were associated with higher mortality rates: advanced New York Heart Association (NYHA) functional class, increased creatinine level, prolonged extracorporeal circulation time and treatment of annular abscess. Logistic multivariate analysis identified advanced NYHA functional class and a creatinine level higher than 1.5 mg/dl as independent predictors of hospital mortality. CONCLUSIONS: Advanced NYHA functional class and higher creatinine levels were independent predictors of hospital mortality in patients submitted for valvular reoperations for prosthetic valve dysfunction.

Adolescent↗

PubMed1986

[Multivariate analysis of factors affecting the prognosis of renal cell carcinoma].

During the last 10 years, we histologically or clinically diagnosed 36 cases of renal cell carcinoma in our department. Concerning the factors affecting the prognosis of renal cell carcinoma, we analyzed 18 data items by mean of quantification II, one of the methods of multivariate analysis. The results were as follow: 1. Operation, stage, age, ESR and tumor weight were found to be significant factors in evaluating the prognosis. 2. The prognosis group and good prognosis group were clearly divided by this analysis.

Adult↗

PubMed1998

Risk factors associated with preterm (<37+0 weeks) and early preterm birth (<32+0 weeks): univariate and multivariate analysis of 106 345 singleton births from the 1994 statewide perinatal survey of Bavaria.

OBJECTIVE: The study was conducted to identify medical, obstetrical and social risk factors associated with early preterm births (<32+0 gestational weeks). STUDY DESIGN: The Statewide Perinatal Survey of Bavaria is a collection of perinatal data from all Bavarian maternity units using a uniform numbered questionnaire. Data on 106345 singleton births from the 1994 Survey were analysed using univariate and multivariate logistic regression analysis. RESULTS: In the multivariate analysis, early preterm birth was associated with premature rupture of the membranes (odds ratio (OR) 1.6, 95% confidence interval (CI) 1.37-1.86), treatment for infertility (OR 1.7, 95% CI 1.19-2.34), previous induced abortion (OR 1.8, 95% CI 1.57-2.13), maternal age >35 years (OR 1.8, 95% CI 1.47-2.16), premature cervical dilatation (OR 2.3, 95% CI 1.86-2.94), a history of stillbirth (OR 3.2, 95% CI 2.13-4.83), a history of preterm birth (OR 3.3, 95% CI 2.45-4.48), maternal age <18 years (OR 3.4, 95% CI 2.03-5.61), malpresentation (OR 3.9, 95% CI 3.10-4.93), preeclampsia (OR 4.0, 95% CI 3.20-4.94), uterine bleeding (OR 5.0, 95% CI 4.08-6.02), preterm labour (OR 7.0, 95% CI 5.94-8.22), and chorioamnionitis (OR 22.3, 95% CI 17.40-28.66). CONCLUSION: These data identify a subgroup of women at an increased risk for early preterm birth and may benefit from an intensified prenatal care. Risk factors related to the obstetrical history, genital infections, preeclampsia and maternal age are the most relevant for early preterm birth.

Abortion, Induced↗

PubMed1987

Refractoriness to random donor platelet transfusions in patients with aplastic anaemia: a multivariate analysis of data from 264 cases.

Frequent platelet support is an essential part of the management of patients with severe aplastic anaemia and platelet transfusions from random donors are usually given as initial therapy. To evaluate those parameters that might correlate with the development of refractoriness to platelets from random donors, we performed a retrospective multivariate analysis in 264 patients with severe aplastic anaemia who presented for allogeneic bone marrow transplantation. Two hundred and ten (79.5%) of these patients had received multiple platelet and red cell transfusions, and 71 (34%) were refractory to random donor platelets. The strongest factor correlating with refractoriness was the presence of lymphocytotoxic antibodies, followed by the number of platelet units previously transfused. However, the latter variable attained significance only when the number of platelet units transfused exceeded 40. When given HLA-compatible platelet transfusions, only five (7%) of the refractory patients did not show a reasonable post-transfusion platelet increment. Measures which would delay or prevent platelet alloimmunization might include a policy of therapeutic rather than prophylactic platelet transfusions, and referring patients early in the course of their disease for marrow grafting if a suitable donor is available.

Adolescent↗

PubMed1988

Restenosis after balloon dilatation of coronary stenosis, multivariate analysis of potential risk factors.

This study was undertaken to analyze change in stenosis caliber up to six months after PTCA with respect to regression or progression as well as to detect factors which possibly influencing the restenosis rate. A computer assisted system with high accuracy was used for two-dimensional quantitation of stenosis. A linear multivariate analysis was applied to quantitative and qualitative angiographic data as well as to clinical findings obtained before, immediately after and six months post-PTCA in 95 consecutive patients in whom 101 stenoses were dilatated. All patients were on a standard medical regimen of aspirin or coumadin and nifedipine. After six months, 56 patients showed a change in minimal stenosis area (mSA) of less than 1 mm2 (no progression), 33 patients showed a decrease in mSA of greater than 1 mm2 which rendered the stenosis with greater than 70% luminal reduction, and 12 patients showed a decrease in mSA of greater than 1 mm2 which did not, however, result in high-grade luminal narrowing. With regard to factors capable of affecting restenosis rate, there was no relationship between extent of dilatation achieved, local dissection, stenosis configuration or localization, calcification, patient age, sex, duration of symptoms, overweight, cholesterol, triglycerides, HDL, LDL, smoking, hypertension or diabetes. However, a relationship was found between the discontinuation of aspirin or coumadin as a result of GI side effects or bleeding (2% no progression; 20% progression). Thus, antiplatelet therapy appears to be important with respect to long-term results after PTCA.

Angina Pectoris↗

PubMed1989

Adenocarcinoma of the stomach: a multivariate analysis of clinical, pathologic and treatment factors.

We performed a retrospective prognostic study of 246 patients treated for adenocarcinoma of the stomach with curative intent over the period 1960-1984. Lesions of the cardia and gastro-esophageal junction were excluded. The study examined the prognostic influence of nine clinicopathologic and six treatment variables by univariate and multivariate analysis. Five-year survival rates (Kaplan-Meier) for TNM stages, IA, IB, II, IIIA, and IIIB were 88%, 80%, 55%, 30% and 9%, respectively. The Cox models of proportional hazards identified five independent variables predictive of death from gastric cancer: high TNM stage, metastatic involvement of four or more regional lymph nodes, poor differentiation of tumor, splenectomy and insufficient scope of regional lymph-adenectomy relative to the nodal stage (R minus N less than 1.5).

Adenocarcinoma↗

PubMed1998

[Extent and mode of metastatic spread to lymph nodes in patients with adenocarcinoma of the gastric cardia: a multivariate analysis using COX proportion hazard model].

OBJECTIVE: To investigate lymph node metastases (LNM) and assess LNM level accurately after standard resection. METHODS: An analysis was done in 736 patients with resected gastric cardia cancer whose postoperative survival time was longer than three months, through comparison of prognosis, frequency of LNM and ratio of the number of invaded to removed lymph nodes (I/R), using COX multivariate analysis model. RESULTS: (1) The most important prognostic variables were I/R, left gastric artery LNM, lesser curvature LNM, and paracardia LNM. (2) The patients without LNM had better survival (P < 0.001). (3) There were a relatively regular way of LNM and significant difference between LNM of single site and that of multiple sites on the frequency of LNM and I/R, respectively (P < 0.05). (4) There was significantly different I/R among group 1 (single paracardia LNM and single lesser curvature LNM), group 2 (single left gastric artery LNM and paracardia plus lesser curvature LNM) and group 3 (multiple sites in association with left gastric artery LNM) (P < 0.05). CONCLUSION: The dissemination of LNM seems to be as follows: from paracardia lymph nodes to distant lymph nodes, and from a single lymph node of one site to multiple sites with many lymph notes involved. It is suggested that group 1 LNM belongs to station 1, group 2 LNM to station 2 and group 3 LNM to station 3 according to their I/R.

Adenocarcinoma↗

PubMed1987

Survival in systemic lupus erythematosus. A multivariate analysis of demographic factors.

We analyzed survival rate and important clinical outcomes in 411 patients with systemic lupus erythematosus who were seen at our center between 1969 and 1984. All eligible subjects met 4 of the revised American Rheumatism Association criteria for systemic lupus erythematosus and all were seen within 2 years of diagnosis. Mean followup was 75.6 months. Multivariate analysis suggested significant independent effects of race (P = 0.0139) and socioeconomic status (P = 0.0326) on survival. No evidence of diminished lupus-related mortality with age was documented. Previously reported findings of improved survival rate with age may have been confounded by differences in race distribution between the younger- and older-onset groups.

Adult↗

PubMed2004

[Prognostic significance of clinical and pathomorphological factors in colorectal cancer: a uni- and multivariate analysis].

The aim of this study was to estimate the prognostic value of clinical and pathomorphological factors in cancer of the colon and rectum. We studied seventy-seven patients subjected to a radical surgery with a five-year follow-up. Survival was calculated using the Kaplan-Meier method and compared by log-rank test. Multivariate analysis was performed using Cox's regression model. Overall 5-year survival was 68%. Primary tumour spread beyond the bowel wall and regional lymph node involvement appeared to be independent prognostic factors, significantly influencing the survival of patients. Other variables including patient's age and sex, tumour location, symptom duration before treatment onset, grade of differentiation and mucinous histology had no significant impact on prognosis. Tumour spread beyond the bowel wall and metastases to regional lymph nodes are the most useful prognostic factors in patients with colorectal carcinoma. In routine practice the clinical stage of cancer should remain a reference against which other clinical and pathomorphological variables are assessed.

Colorectal Neoplasms↗

PubMed1987

[Recovery in aphasia (Part 3)--Study by multivariate analysis].

In order to elucidate the factors which have influence on the prognosis of aphasia, correlation between recovery rate of aphasia and the five factors, i.e. initial evaluation of speech test, age, educational level, time between onset and institution of therapy and size of abnormal findings in CT (computed tomography), was studied in 76 right-handed aphasic patients, using multivariate analysis. Cluster analysis and factor analysis were used for analysis of five factors and multiple regression analysis was used for estimation of recovery rate of aphasia. The method of calculation of recovery rate of aphasia is the same to our previous report. The results obtained were as follows: As to analysis of factors, first similarity group among initial evaluation of speech test, recovery rate of aphasia and educational level and second similarity group among time between onset and institution of therapy, size of abnormal findings in CT and age were observed. As to the estimation of recovery rate of aphasia, multiple correlation coefficient of regression analysis using five factors were 0.758, 0.444, 0.627, 0.620, 0.810 and 0.375 respectively in total score, hearing, speaking, reading, writing and calculation on standard language test of aphasia. As to the weight or partial correlation coefficient of regression analysis to the five factors, initial evaluation of speech test, time between onset and institution of therapy and educational level were 129.46, -49.93 and 45.65 respectively and the one of the size of abnormal findings in CT was not high. Stepwise multiple regression analysis of five factors were made.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed2005

Multivariate analysis of infrared spectra for monitoring and understanding the kinetics and mechanisms of adsorption processes.

Water adsorption onto thin zeolite 3A wafers has been investigated as a function of time, water vapor concentration, and zeolite sample mass using mid-infrared spectroscopy coupled with multivariate data analysis. Principal component analysis (PCA) of the spectral region of the water combination band was used for quantitative characterization of water adsorption onto the zeolite. The kinetics of the adsorption of water are found to be very reproducible and nearly linear with time. The kinetics of water adsorption based on data from different masses of zeolite are consistent with a diffusion/immobilization model for which the interparticle diffusion rate is comparable to the rate of adsorption. The infrared zeolite bands (1340-1550 cm(-1)) change during the adsorption process and yield more detail about the adsorption sites of the material. PCA applied to the zeolite bands was not directly interpretable. However, multivariate curve resolution applied to the spectral region containing the zeolite bands readily demonstrates that zeolite 3A has three water adsorption sites or environments that are sequentially occupied. Potential explanations for the observations of the multivariate curve resolution (MCR) analysis of these infrared (IR) kinetic adsorption experiments are presented. The explanation most consistent with our data suggests that water adsorbs sequentially on the zeolite to form single, double, and triple water adsorption on single zeolite adsorption sites. The combination of infrared spectroscopy and multivariate analysis is therefore demonstrated to be a powerful method to study detailed adsorption kinetics and mechanisms of the adsorption of molecules onto surfaces.

Adsorption↗

PubMedDate not supplied

[Multivariate analysis as a means of access to optimal pharmacochemical specificity and to molecular archetypes].

For complex works as studies relationships structure-activity, in heterogeneous therapeutic families we have selected mathematical methods founded upon systemic approach rather analytic one, appealing to bibliographical data, taking into consideration a plurality of biological targets and envisaging structural extrapolations rather than interpolations. Compared with classical QSAR, multivariate analysis (factorial analysis and multidimentional data reduction) intend from structuration of whole complex items to definite spheres of correlations between structural parameters and biological ones to issue then on a symetric typology of this two groups of parameters. These approaches have not only a descriptive character but lead to operational conclusions through an interactive dialogue with data bank; for example: --to explore acting potentiality of others molecular families or/and particular sub-structures --to find chemical sequences of molecules synthesized for other aims but not again experimented for this property. The case of antiparasitic agents is here developed.

Analysis of Variance↗