Misuse of multivariate analysis.
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Age Factors↗
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Results for “multivariate analysis”
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Can multivariate analysis rule out causality?
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Causality↗
[The multivariate analysis of clinico-laboratory data in stomatology].
The authors demonstrate the potentialities of multidimensional analysis methods: component, cluster, and discriminant as exemplified by clinico-laboratory examinations of 26 patients with medium-severe periodontitis and concomitant diseases. A two-stage modification of multidimensional grouping of biomedical objects is suggested. The first stage implies detection of the principal components and their estimation for each examinee. The second stage consists in realization of multidimensional grouping method according to G. S. Kil'dishev and Iu. I. Abolentsev in relation to individual component values. Different typologically homogeneous groups of patients with a specific microbiologic and biochemical status evidently requiring a differentiated approach to treatment may be singled out within the frames of a current classification of periodontal diseases basing on clinical and laboratory data.
Adolescent↗
Univariate and multivariate analysis of prognostic factors in the surgical treatment of hepatocellular carcinoma in cirrhotic patients.
BACKGROUND/AIMS: Evaluation of the short- and long-term outcome of liver resections for HCC in cirrhotic patients. METHODOLOGY: A retrospective analysis was performed on 106 consecutive cirrhotic patients with HCC resected between June 1974 and September 2002. Univariate and multivariate analyses were performed on several clinicopathological variables to analyze factors affecting the long-term outcome and intrahepatic recurrence. RESULTS: Overall mortality and morbidity were 10.7% and 26% respectively. These rates significantly decreased in the last years: from 1997 to 2002 no hospital mortality has been recorded. After a median follow-up of 19 months (interquartile range: 10-36), tumor recurrence appeared in 25 patients (23.5%). The 1-, 3-, and 5-year overall survival rates were 86.6%, 70.3%, and 60.6%, respectively. The 1-, 3-, and 5-year disease-free survival rates were 86.3%, 58.1%, and 40.7%. Univariate analysis showed that viral etiology of cirrhosis (p=0.03), presence of multiple nodules (p=0.02) and vascular invasion (p=0.05) are related to a worse long-term survival. Multivariate analysis showed that only the viral etiology of cirrhosis and the presence of multiple nodules were significant independent prognostic factors. CONCLUSIONS: Results after hepatic resection for HCC in cirrhotic patients can be improved by using a limited surgical approach. The viral etiology of cirrhosis, the presence of multiple nodules and vascular invasion negatively affected recurrence rate and long-term survival.
Aged↗
Risk factors in mass screening for breast cancer, multivariate analysis of data from the Cuban diagnosis pilot study.
The evolution of mammography has provided possibilities for mass screening programs. Early diagnosis is considered the most important factor in reducing the breast cancer mortality but the mass screening is very expensive if we include all female population. In this paper we show the results of an early diagnosis pilot study with a multivariate data analysis. Data concerning risk factors (age, age at menarche, menopause, parity, age at first childbirth, lactation, abortions and previous benign breast disease) were recorded in 438 patients with breast carcinoma and 1750 patients with benign breast diseases diagnosed in the Early Diagnosis Pilot Program at the National Institute of Oncology and Radiobiology in Cuba. A group of 449 healthy women living in Havana City was also studied. Age and age at first childbirth were the major factor considered. Multivariate data analysis allowed to build stratification trees identifying subgroups with different breast cancer incidence. The usefulness of these stratifications for screening with optimal coverage, sufficiency and efficacy, is discussed.
Adult↗
Multivariate analysis of prognostic factors in chronic myelogenous leukemia.
The prognostic importance of patient pretreatment clinical and laboratory features were investigated in a group of 50 patients with Philadelphia chromosome-positive benign phase chronic myelogenous leukemia. The overall median survival time was 30 months. The patient characteristic associated with shortened survival was the male sex. Anemia, thrombocytosis or thrombocytopenia tened to have adverse effect on survival. A multivariate regression analysis demonstrated only sex difference to be of prognostic importance. Evaluation of the effect of therapy showed that intensive chemotherapy was not superior to single agent chemotherapy.
Adult↗
Prostatic carcinoma: a multivariate analysis of prognostic factors.
Tissue specimens from 150 patients with localised prostatic carcinomas and 116 patients with prostatic carcinomas with distant metastases were analysed for histological grade (WHO and Gleason) and immunoreactivity for prostate acid phosphatase (PAP), prostate-specific antigen (PSA), neurone-specific enolase (NSE), p53 protein, c-erbB-2 protein, cytokeratins (AE1/AE3) and vimentin. After stratification for the presence or absence of distant metastases, multivariate regression analysis revealed that WHO grading was the most powerful independent prognosticator, followed by age and prostate acid phosphatase expression. There was a trend towards reduced survival with decreasing prostate-specific antigen reactivity. The Gleason system showed poor prognostic ability. The analysis predicted reduced survival in the presence of extensive neurone-specific enolase reactivity, mostly because of one case of small-cell carcinoma.
Acid Phosphatase↗
Multivariate analysis of the risk for pulmonary complication after gastrointestinal surgery.
AIM: To identify the risk factors for postoperative pulmonary complications (PPC) after gastrointestinal surgery. METHODS: A total of 1 002 patients undergoing gastrointestinal surgery in the Second Affiliated Hospital, Sun Yat-Sen University, during December 1999 and December 2003, were retrospectively studied. RESULTS: The overall incidence of PPC was 22.8% (228/1,002). Multivariate logistic analysis identified nine risk factors associated with PPC, including age odds ratio (OR = 1.040) history of respiratory diseases (OR = 2.976), serum albumin (OR = 0.954), chemotherapy 2 wk before operation (OR = 3.214), volume of preoperative erythrocyte transfusion (OR = 1.002), length of preoperative antibiotic therapy (OR=1.072), intraoperative intratracheal intubation (OR = 1.002), nasogastric intubation (OR = 1.050) and postoperative mechanical ventilation (OR = 1.878). Logistic regression equation for predicting the risk of PPC was P(1) = 1/[1+e(-(-3.488+0.039 x Y+1.090 x Rd+0.001 x Rbc-0.047 x Alb+0.002 x Lii+0.049 x Lni+0.630 x Lmv+0.070 x Dat+1.168 x Ct))]. CONCLUSION: Old patients are easier to develop PPC.
Adolescent↗
Multivariate analysis of single unit cells in electron crystallography.
High-resolution electron cryomicroscopy of two-dimensional protein crystals is associated with extremely noisy raw data in which even the crystal lattice often cannot be discerned. Correlation averaging procedures, aimed at calculating the total average of all unit cells of crystals in order to reduce noise, are now used routinely in electron crystallography. Multivariate statistical analysis (MSA) may be used for finding not only the average structure but also for quantifying the systematic departures from that average within the population of individual unit cells. We show that the MSA approach is applicable to single unit-cell images in the low-dose (< 10 electrons/A2), high-resolution (< 5 A) realm using 400 keV electron spot-scan images of ice-embedded gp32*I protein crystals. Our feasibility study opens a pathway toward exploiting these naturally occurring variations on the unit-cell theme in order to achieve higher-resolution three-dimensional reconstruction results, or to better understand the dynamic behaviour of molecules within two-dimensional crystals. We explain how single unit-cell images can be processed and classified into homogeneous groups, and we review how the results of such discriminate averaging may subsequently be exploited within the context of conventional "h, k"-space electron crystallographic approaches. Variations among the individual unit cells may thus be one of the most significant resolution-limiting factors currently experienced in electron crystallography. The quantitative assessment and exploitation of such variations may lead to an increased performance of electron crystallographic procedures.
Bacteriophage T4↗
Near infrared spectroscopy, cluster and multivariate analysis hyphenated to thin layer chromatography for the analysis of amino acids.
A method based on near-infrared spectroscopy (NIRS) was developed for the rapid and non-destructive determination and quantification of solid and dissolved amino acids. The statistical results obtained after optimisation of measurement conditions were evaluated on the basis of statistical parameters, Q-value (quality of calibrations), R(2), standard error of estimation (SEE), standard error of prediction (SEP), BIAS applying cluster and different multivariate analytical procedures. Experimental optimisation comprised the selection of the highest suitable optical thin-layer (0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm), sample temperature (10-30 degrees C), measurement option (light fibre, 0.5 mm optical thin-layer; boiling point tube; different types of cuvettes) and sample concentration in the range between 100 and 500 ppm. Applying the optimised conditions and a 115-QS Suprasil cuvette (V = 400 microl), the established qualitative model enabled to distinguish between different dissolved amino acids with a Q-value of 0.9555. Solid amino acids were investigated in the transflectance mode, allowing to differentiate them with a Q-value of 0.9155. For the qualitative and quantitative analysis of amino acids in complex matrices NIRS was established as a detection system directly onto the plate after prior separation on cellulose based thin-layer chromatography (TLC) sheets employing n-butanol, acetic acid and distilled water at a ratio of 8:4:2 (v/v/v) as an optimised mobile phase. Due to the prior separation step, the established calibration curve was found to be more stable than the one calculated from the dissolved amino acids. The found lower limit of detection was 0.01 mg/ml. Finally, this optimised TLC-NIRS method was successfully applied for the qualitative and quantitative analysis of L-lysine in apple juice. NIRS is shown not only to offer a fast, non-destructive detection tool but also to provide an easy-to-use alternative to more complicated detection methods such as mass spectrometry (MS) for qualitative and quantitative TLC analysis of amino acids in crude samples.
Amino Acids↗
Bleeding complications to oral anticoagulant therapy: multivariate analysis of 1010 treatment years in 551 outpatients.
One thousand and ten patient years of oral anticoagulant therapy with vitamin-K-antagonists were reviewed with regard to major bleeding complications. The incidence of bleeding that necessitated hospital admission was 2.7% per year (95% confidence limits, 1.7-3.7%). The major source of bleeding was the alimentary tract, whereas no cases of intracranial bleeding were found. Various factors with potential effects on the bleeding risk were evaluated by multivariate statistical analysis, and the following independent risk factors were identified: age greater than 75 years and hypertension increased the bleeding risk by 10.5% and 4.5%, respectively. Each recorded prothrombin value significantly below the therapeutic range increased the bleeding risk by 3.9%, and each year of treatment increased the risk by 2.0%. These figures may be used to estimate the risk of major bleeding in an individual patient. Current treatment with thiazide diuretics was found to increase the bleeding risk by 5.2%. However, this observation requires further documentation and analysis. Although no lethal episodes of bleeding occurred, the developing field of indications for oral anticoagulant therapy should be considered on the basis of a continuous substantial risk of major bleeding.
Adolescent↗
Prospective predictors of urinary continence after anatomical radical retropubic prostatectomy: a multivariate analysis.
The aim of this work was to evaluate variables that predict time to pad-free urinary continence after anatomical radical prostatectomy (ARP). Sixty consecutive prostate cancer patients who underwent ARP by one surgeon were studied. Pad-free urinary continence was prospectively determined by patient interviews and confirmed on physical examination and by the urinary domain of the Extended Prostate Inventory Composite (EPIC) Health Related Quality of Life questionnaire. A time-dependent Cox multivariate regression analysis was performed to determine which variables significantly correlated with time to pad-free urinary continence. Increasing prostate size (cc), increasing prostate urethral length (cm) and surgical technique (wide excision of the neuro-vascular bundle) correlated with a significantly (P<0.05) prolonged time to achieve pad-free urinary continence. In conclusion, prostate size and surgical technique were the most useful variables in predicting time to pad-free urinary continence after ARP.
Humans↗
The Belgrade childhood diabetes study: a multivariate analysis of risk determinants for diabetes.
BACKGROUND: The aim of this study was to evaluate some hypotheses about factors related to the development of type 1 diabetes mellitus. METHODS: A case-control study was conducted in Belgrade during the period 1994-1997. A total of 105 recently onset diabetic and 210 control children, individually matched by age (+/-1 year), sex and place of residence, were included in the study. RESULTS: According to multivariate regression analysis, the following factors were related to type 1 diabetes: stressful events and symptoms of psychological dysfunction during the 12 months preceding the onset of the disease [odds ratio (OR) 3.48, 95% confidence interval (CI) 2.15-5.65; and OR 2.15, 95% CI 1.33-3.48], irregular vaccination (OR 16.98, 95% CI 1.38-208.92), infection during 6 months preceding the onset of the disease (OR 4.23, 95% CI 1.95-9.17), higher education of father (OR 1.50, 95% CI 1.05-2.14), mother's consumption of nitrosoamines-rich food during pregnancy (OR 4.33, 95% CI 1.95-9.61), alcohol consumption by father (OR 3.80, 95% CI 1.64-8.78), insulin-dependent and non-insulin-dependent diabetes mellitus in three generations of children's relatives (OR 20.04, 95% CI 4.73-84.81; and OR 5.52, 95% CI 2.45-12.46), and use of ultrasound diagnostic techniques during pregnancy (OR 0.42, 95% CI 0.17-1.00). CONCLUSIONS: Among non-genetic factors, those affecting the child during pregnancy are especially important because of their preventability.
Adolescent↗
Regarding "Surgical transluminal femoropopliteal angioplasty: multivariate analysis outcome".
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Angioplasty, Balloon↗
Multivariate analysis and expert systems.
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Chemistry, Clinical↗
Refractory anemia with excess of blasts: a multivariate analysis of prognostic factors in 91 patients and a simplified scoring system for predicting survival.
Prognosis in myelodysplastic syndromes is extremely variable. The prognostic value of the FAB classification has been demonstrated in many studies. However, within the same FAB subtype, some patients may experience prolonged survival, whereas others die in a few weeks. This prognostic heterogeneity makes the therapy decision difficult. In an attempt to identify significant prognostic factors for survival in refractory anemia with excess of blasts (RAEB), clinical and hematological characteristics were analyzed in 91 patients. Multivariate regression analysis showed that bone marrow total blast cells percentages, sex and hemoglobin level were the characteristics significantly associated with survival. A scoring index based upon these three characteristics may be proposed and had a great prognostic value (p < 0.00001). It allows us to separate patients into three groups with low, intermediate and high score with a median survival of 239, 133 and 45 days for each group respectively. This scoring index may be useful in the design of therapy and analysis of future clinical trials. However, its predictive value needs to be confirmed in other series.
Adult↗
[Multivariate analysis of local response to preoperative treatment in patients with infiltrating carcinoma of the bladder].
The article presents a multivariate study carried out by means of a logistic regression of local responses (reduction to stage p0, p1 or p 'in situ') in 82 patients with transitional infiltrant carcinoma of the bladder, undergoing 3 different types of radical therapy: 25 patients treated with TUR and radical cystectomy; 33 patients treated with TUR, pre-operative radiotherapy (45-60 Gy) and radical cystectomy; and 24 patients treated with TUR, intra-operative radiotherapy (15 Gy), external radiotherapy (46 Gy), neo-adjuvant chemotherapy and radical cystectomy. Local response increased with the intensity of pre-operative therapy, there being a better relationship with this approach than with the initial clinical stage of the tumour. The factors which better explain the prospect of an objective local response are the use of radiotherapy associated to chemotherapy and the absence of metastatic lymphatic nodes. These 2 variables can adequately predict the local response in 87% of patients.
Adult↗
Multivariate analysis of data from two-dimensional electrophoretic separation of macromolecules.
Recent work on two-dimensional electrophoretic separation of molecules has concentrated on technical aspects of molecule identification, leaving little in the way of time and resources to explore new, effective methods for analyzing the data thus produced. We present a method for coding electrophorograms that is capable of capturing sufficient information in order that subsequent analysis might be revealing. Along with this coding method, we describe a flexible approach to the analysis of electrophoretic data employing multivariate methods for summarization and comparison. In this we have found an effective vehicle for revealing some unexpected properties of the electrophorograms.
Electrophoresis↗