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Results for “Discriminant Analysis”

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PubMed2001

[Risk factors for Crohn's disease relapse after treatment of intestinal stenosis].

BACKGROUND: Postoperative recurrences of Crohn's disease (CD) has been widely investigated in previous studies. Nevertheless, the risk factors for CD recurrence in patients presenting with intestinal stenosis are not clearly identified. PATIENTS AND METHOD: Thirty consecutive patients out of a cohort of 134 patients with CD presented with an intestinal stenosis diagnosed between 1995 and 1999. Epidemiological, clinical, and therapeutic data were carefully recorded. A univariate analysis followed by stepwise descending discriminant analysis was performed. RESULTS: Sixteen patients (53%) underwent surgery, six received steroid therapy, eight were given antibiotics, and seven took immunosuppressive drugs. The mean follow-up after medical or surgical management was 2.8 years. Thirteen patients (43%) had CD relapse during the follow-up. Considering the univariate analysis, the existence of a previous appendectomy and the persistence of tobacco consumption were significantly associated with the risk of CD relapse during the follow-up. The stepwise descending discriminant analysis identified three independant factors: tobacco consumption (p = 0.007), previous appendicectomy (p = 0.04) and duration of the follow-up (p = 0.02). CONCLUSION: The CD relapse after the management of small bowel stenosis occurred in 43% of the patients within a mean follow-up of 2.8 years. The significant factors associated with the risk of CD relapse were tobacco consumption, previous appendectomy and duration of the follow-up.

Adult↗

PubMedDate not supplied

Optimal approach for classification of acute leukemia subtypes based on gene expression data.

The classification of cancer subtypes, which is critical for successful treatment, has been studied extensively with the use of gene expression profiles from oligonucleotide chips or cDNA microarrays. Various pattern recognition methods have been successfully applied to gene expression data. However, these methods are not optimal, rather they are high-performance classifiers that emphasize only classification accuracy. In this paper, we propose an approach for the construction of the optimal linear classifier using gene expression data. Two linear classification methods, linear discriminant analysis (LDA) and discriminant partial least-squares (DPLS), are applied to distinguish acute leukemia subtypes. These methods are shown to give satisfactory accuracy. Moreover, we determined optimally the number of genes participating in the classification (a remarkably small number compared to previous results) on the basis of the statistical significance test. Thus, the proposed method constructs the optimal classifier that is composed of a small size predictor and provides high accuracy.

Algorithms↗

PubMed2004

Prevalence and significance of minor anomalies in children with impaired development.

AIM: To compare the prevalence of Waldrop's minor physical anomalies in children with developmental disorders (mental retardation, hearing and visual impairment) and healthy schoolchildren. METHODS: The study was carried out on a sample of 469 children (223 children with developmental disorders and 246 healthy schoolchildren). RESULTS: Significant differences were found between the children with developmental disorders and the healthy children with regard to the number of minor anomalies and their weighted scores according to Waldrop. Multivariate discriminant analysis with two discriminative functions explained as much as 96.51% of the total variability and significantly distinguished the healthy children from the children with developmental disorders. However, no clear distinction was found between the mentally retarded children and those with visual impairment. Interrelation of the number and sum of the weighted scores of minor anomalies showed similar minor anomalies in the mentally retarded children (mean per person 3.65 and 3.82, respectively), the children with visual impairment (3.24 and 3.50), the children with hearing impairment (3.84 and 3.67) and the control group (1.70 and 1.46), although at different levels. CONCLUSIONS: The high prevalence of multiple minor anomalies in children with developmental disorders suggests that during early development, factors which cause the specific developmental disorder and the occurrence of a minor anomaly have a joint effect.

Adolescent↗

PubMed2001

Multivariate discriminant function based on six biochemical markers in blood can predict the cirrhotic evolution of chronic hepatitis.

BACKGROUND: Serologic markers have been proposed for monitoring hepatic fibrosis in chronic active liver disease. Because none of these markers, when used singly, is totally satisfactory, we developed and evaluated a multivariate approach. METHODS: We studied two cohorts of chronic hepatitis (54 patients) and cirrhosis patients (49 patients) to identify a panel of biochemical markers that discriminates between the two diseases. Using multivariate discriminant analysis, we selected a function, based on the concentrations of six biochemical markers (fibronectin, prothrombin, pseudocholinesterase, alanine aminotransferase, manganese superoxide dismutase, and N-acetyl-beta-glucosaminidase). We then prospectively validated this function on a second temporal cohort of patients. RESULTS: Multivariate discriminant analysis correctly classified 93.7% of patients (94.3% of chronic hepatitis and 92.9% of cirrhosis patients) in the first cohort and 85% of patients (89.5% of chronic hepatitis patients and 81% of cirrhosis patients) in the second cohort. CONCLUSIONS: Discriminant analysis of results of six inexpensive biochemical markers provides a high predictive value for differentiation between liver cirrhosis and chronic hepatitis. Consequently, these biochemical markers condensed into a multivariate discriminant analysis value for each patient provide information that can be contributory for subsequent options during the evolution of the natural history of chronic hepatitis.

Biomarkers↗

PubMed2003

Sex determination from the talus of South african whites by discriminant function analysis.

The field of forensic anthropology involves the building of an antemortem profile of an individual from skeletal remains. This includes sex and race determination and age and stature estimation. Since most bones that are conventionally used for sex determination are often recovered either in a fragmented or incomplete state, it has become necessary to use denser bones that are often recovered intact, eg, the patella, calcaneus, and talus. Thus the aim of this study is to assess the sex-determining ability of each of the measurements of the talus and derive discriminant function equations for sex determination in the South African white population. Sixty male and 60 female tali of South African whites obtained from the Raymond A. Dart Collection of Human Skeletons were used. Nine measurements were taken on each talus. Descriptive statistics and discriminant function analysis were performed on the acquired data. The basic statistics showed that all measurements were sexually dimorphic. Univariate, stepwise, and direct discriminant function equations were generated for use in sex determination. The level of average accuracy of sex classification was 80% to 82% for the univariate method, 85% to 88% for the stepwise method, and 81% to 86% for the direct method. It is concluded that the talus of South African whites is useful for sex determination.

Adolescent↗

PubMed2002

Relationship between acute organophosphorus pesticide poisoning and damages induced by free radicals.

OBJECTIVE: To study the relationship between abnormal reactions of free radicals in bodies of patients with acute organophosphorus pesticide poisoning (AOPP) and damages induced by free radicals. METHODS: 58 AOPP patients and 58 healthy adult volunteers (HAV) were enrolled in an independent samples control design, in which spectrophotometric methods were used to determine the concentrations of nitric oxide (NO) and lipoperoxides (LPO) in plasma, and LPO in erythrocytes, vitamin C (VC), vitamin E (VE) and beta-carotene (beta-CAR) in plasma as well as activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and acetylcholinesterase (AChE) in erythrocytes. RESULTS: Compared with the average values of every biochemical parameter in the HAV group, the average values of LPO in plasma and in erythrocytes, and NO in plasma in the AOPP group were significantly increased (P = 0.000001), while the average values of VC, VE, beta-CAR in plasma as well as SOD, CAT, GSH-Px and AChE in erythrocytes in the AOPP group were significantly decreased (P = 0.000001). The findings of Pearson product-moment correlation analysis between the value of AChE in erythrocytes and the values of above biochemical parameters for 58 AOPP patients showed that there was a significant linear negative correlation between AChE in erythrocytes and LPO, NO in plasma, and LPO in erythrocytes (P = 0.000001-0.001319), while there was a significant linear positive correlation between AChE in erythrocytes and VC, VE, beta-CAR in plasma as well as SOD, CAT, GSH-Px in erythrocytes (P = 0.000013-0.000824). The results of discriminant analysis of above chemical parameters for 58 AOPP patients and 58 HAV suggested that the correct rates of discriminant analysis were increased to 100% when the values of AChE and LPO in plasma and in erythrocytes, or AChE and others, were jointly used for the discriminant analysis. CONCLUSION: The findings of the present study suggest that a series of free radical reactions in AOPP patients' bodies are pathologically aggravated, and the discriminant analysis used the above biochemical parameters could markedly increase its correct rates for AOPP patients.

Acute Disease↗

PubMed2002

Improving the prediction of outcome in severe acute closed head injury by using discriminant function analysis of normal auditory brainstem response latencies and amplitudes.

OBJECT: The auditory brainstem response (ABR) is a useful addition to standard medical measures for predicting outcome in patients with severe acute closed head injury (ACHI). Limiting this success, however, is the poor predictive value of a so-called "normal" ABR. In this study the authors used discriminant function analysis (DFA) of ABR Wave I, III, and V latencies and amplitudes to improve the predictive accuracy of the normal ABR, both as a single measure and in combination with other standard medical measures. METHODS: The DFAs were conducted using the ABR and medical results in 68 patients with severe ACHI (30 who died [ACHI-died], and 38 who survived [ACHI-lived]) who presented with normal ABR responses in the neurosurgical intensive care unit of the authors' hospital in Johannesburg. All patients had undergone surgery to remove an intracranial hematoma. Correct predictions of outcome by ABR DFA measures were 83% for the ACHI-died group (48% at > or = 90% confidence level) and 87% for the ACHI-lived group (71% at > or = 90% confidence level); by medical DFA measures the correct predictions were 83% for the ACHI-died group (96% at >; or = 90% confidence level) and 95% for the ACHI-lived group (94% at > or = 90% confidence level); and by combined ABR and medical DFA measures correct predictions were 100% for the ACHI-died group (100% at > or = 90% confidence level) and 97% for the ACHI-lived group (100% at > or = 90% confidence level). CONCLUSIONS: The DFA of ABR Wave I, III, and V latencies and amplitudes improved the predictive ability of normal ABR results to rates similar to those obtained using DFA for the medical measures, although at lower confidence levels. The DFA of the combined ABR and medical measures improved correct predictions to rates significantly higher than for either of the measures on its own.

Acute Disease↗

PubMedDate not supplied

Analysis of the antibody repertoire in tears of dry-eye patients.

PURPOSE: It has recently been suggested that dry-eye disease has an underlying autoimmune mechanism. This hypothesis is further supported by the successful treatment of the disease with immunomodulatory drugs such as cyclosporin A. Although it is known that tears contain antibodies, very little is known about the antibody repertoires in tears. It was the aim of this study to analyze the IgA antibody repertoire against ocular antigens in the tears of patients suffering from dry-eye disease and compare it to those of healthy volunteers. METHODS: Two groups were examined: 20 healthy volunteers (controls) and 28 patients suffering from dry-eye disease. The patients were grouped according to the results of the basic secretory test. Patients with values < or =10 and subjective symptoms were classified as dry-eye patients. All tears were tested against Western blots of ocular antigens. For each Western blot, a densitograph was built by digital image analysis, and subsequently a multivariate discriminate analysis was performed. RESULTS: A complex staining pattern was found in the tears of both dry-eye patients and healthy controls. However, the number of peaks was statistically significantly increased (p < 0.05) in the tears of dry-eye patients. The discriminant analysis found a statistically significant difference between the antibody repertoires of both groups (Wilks' lambda = 0.11; p < 0.001). CONCLUSIONS: In this study, it could be shown that the complex antibody repertoires in the tears of patients suffering from dry-eye disease are different from those found in the tears of healthy volunteers. Thus, our findings support the hypothesis that the dry eye disease has an autoimmune mechanism.

Autoantibodies↗

PubMed2001

Quantification of regional contractile function after infarction: strain analysis superior to wall thickening analysis in discriminating infarct from remote myocardium.

OBJECTIVES: Using two-dimensional wall thickening (WT) (expressed as percentage) and strain analysis, regional contractile myocardial function was quantified and compared in 13 control subjects and 13 patients with a first myocardial infarction (MI). The findings in the patient group were related to global ventricular function and infarct size. BACKGROUND: In patients with coronary artery disease, regions with dysfunctional myocardium cannot be differentiated easily from regions with normal function by planar WT analysis. Physiologic factors, in combination with limitations of conventional imaging techniques, affect the calculation of WT. Quantitative assessment of contractile function by magnetic resonance (MR) tissue tagging and strain analysis may be less affected by these factors. METHODS: Two-dimensional regional WT and strain were calculated in three short-axis MR cine and tagged images, respectively. Left ventricular volumes and ejection fraction (EF) were obtained from a series of contiguous short-axis cine images. RESULTS: In patients with infarct-related ventricles, WT and strain analysis both revealed reduced myocardial function, as compared with control subjects (p < 0.005 and p < 0.001, respectively). However, WT analysis yielded no significant regional differences in function between infarct-related and remote myocardium (p = 0.064), whereas strain analysis did (p < 0.005). For detecting dysfunctional myocardium of electrocardiographically and angiographically defined infarct areas, WT analysis had a sensitivity of 69% and a specificity of 92%, whereas strain analysis demonstrated a sensitivity of 92% and a specificity of 99%. The EF correlated with WT (r = 0.76, p < 0.005) and strain (r = 0.89, p < 0.001). CONCLUSIONS: Two-dimensional strain analysis is more accurate than planar WT analysis in discriminating dysfunctional from functional myocardium, and it provides a strong correlation between regional myocardial and global ventricular function.

Aged↗

PubMed1989

Relation between primary tumor shape and biological behavior in breast cancer.

The aim of this study was to investigate the biological significance of tumor shape in breast cancer by considering the shape not as a casual event but as an expression of the behavior and natural history of the tumor. The shape was studied by an analytical morphometry procedure and was related to axillary metastases, which up to now are the most meaningful prognostic factors in this disease. Fifty cases of infiltrating breast carcinoma (25 N+ and 25 N-) were investigated. The shape, studied on subgross sections of the tumor, was considered as the result of two components: the subtle contour irregularities and the main distortions of the figure. The procedures used allowed us to distinguish and to parametrize these two components in order to submit them to univariate analysis (Student's t test), a principal components analysis and, finally, a multivariate discriminant analysis (Hotelling test). The utilized analytical procedures by work-station S.A.M. (S.A.M. work station is a product of "Metamorphosis") consisted of three steps: 1) Extraction of tumor function curve obtained by Kth order polynominals which gives a smoothing effect to the original curve; 2) Evaluation of contour irregularities by Fourier harmonic analysis; 3) Evaluation of shape asymmetry by SAE (shape asymmetry evaluator). We considered also the roundness factors of the original and function curves and finally the maximum tumor diameter. Three parameters relating to contour irregularities (sum and mean value of Fourier harmonic amplitude and percentage of superimposed points) and parameters relating to main distortions of the figure (mean value of SAE) were highly significant (p less than 0.001). The roundness factor of the original curve was more significant (p less than 0.001) than that of the function curve (p less than 0.01) whereas maximum tumor diameter was not significant when tested by Student's t test. Multivariate discriminant analysis allowed 20% of error to be reached by using 3 parameters relating to the shape analysis and the two roundness factors. By using 8 parameters, including maximum tumor diameter, the percentage error was 16%. The results obtained, while they stress the usefulness of the employed procedure, reveal that shape of the tumor, together with its dimensions, is an important expression of the biological behavior relating to metastatic spread.

Analysis of Variance↗

PubMed1992

[Study of quantitative diagnosis of cerebral arteriosclerosis].

On the basis of clinical diagnostic criterion of cerebral arteriosclerosis, we selected, 72 patients with cerebral arteriosclerosis, 72 patients with suspected cerebral arteriosclerosis and 70 healthy individuals and screened 42 variables obtained from clinical and accessory examination with a stepwise discriminant analysis and a stepwise regression analysis. Finally we performed a logistic discriminant analysis of 15 selected variables in order to establish diagnostic discriminant formulas, Ya and Yc. It was found that a diagnostic coincidence rate for rediscriminant analysis of 212 individuals with the formulas was 100%. Very high sensitivity (96.7%), specificity (100%), positive predicted value (100%), negative predicted value (83.3%) and accuracy (97.1%) were noted in a prospective double-blind test on 34 subjects. The authors suggest that the discriminant formulas Ya and Yc established for diagnosis of cerebral arteriosclerosis be widely applicated.

Aged↗

PubMed1994

[Focus on a quick reading of nailfold capillaroscopy].

The diagnostic value of nailfold capillaroscopy was assessed through blind analysis of a continuous series of 307 examinations and a method for quick reading of nailfold capillaroscopy was elaborated with discriminant analysis. The best criteria for predicting the existence of a systemic disease were: major dystrophies (megacapillary, neocapillary and regressive capillary), minor dystrophies and capillary bed abnormalities, especially in patients presenting with vascular disorders of the upper extremities. Capillaroscopic stages and existence of systemic disease were significantly correlated. Discriminant analysis could globally predict the existence of a systemic disease with age and 4 criteria. In subjects with vascular disorders of the upper extremities it needed only age and 3 criterias (abnormal coloration, major dystrophy presence and percentile of minor dystrophies greater than 15%) but without higher diagnostic value (94.2% of patients with systemic disease and 65.6% of patients without systemic disease were correctly classified). Discriminant analysis allows quick reading of nailfold capilloroscopy in the first examination of patients with vascular disorders of the upper extremities.

Adult↗

PubMed2006

Authentication of the botanical and geographical origin of honey by mid-infrared spectroscopy.

The potential of Fourier transform mid-infrared spectroscopy (FT-MIR) using an attenuated total reflectance (ATR) cell was evaluated for the authentication of 11 unifloral (acacia, alpine rose, chestnut, dandelion, heather, lime, rape, fir honeydew, metcalfa honeydew, oak honeydew) and polyfloral honey types (n = 411 samples) previously classified with traditional methods such as chemical, pollen, and sensory analysis. Chemometric evaluation of the spectra was carried out by applying principal component analysis and linear discriminant analysis, the error rates of the discriminant models being calculated by using Bayes' theorem. The error rates ranged from <0.1% (polyfloral and heather honeys as well as honeydew honeys from metcalfa, oak, and fir) to 8.3% (alpine rose honey) in both jackknife classification and validation, depending on the honey type considered. This study indicates that ATR-MIR spectroscopy is a valuable tool for the authentication of the botanical origin and quality control and may also be useful for the determination of the geographical origin of honey.

Analysis of Variance↗

PubMed1988

[The possibility of modern segregation analysis to discriminate monogenic and multifactorial types of the inheritance of traits. The reliability of models and the power of the analysis].

Using computer simulation of family data sets within segregation analysis limits the comparative research of the autosomal major locus model (MLM) and the multifactorial model (MFM) which described the basic types of inheritance of the alternative traits (affected--nonaffected) has been conducted. Robustness of models (statistical aspect) and the power of the analysis (its possibility to discriminate MLM and MFM) are tested. It is shown that permissible level of relative errors for estimated population's frequency is increased, when the values of parameters of models are increased (with decrease of sporadic cases' portion). The power of the analysis is the greatest in the field of greatest robustness of models: the higher the parameters of models, the portion of sporadic cases being low, the stronger the power of the analysis. MFM satisfactorily describes family distribution given by additive MLM. On the contrary, if the MLM corresponds to the multifactorial traits, this model is additive. It is shown that the possibility of the analysis to reject alternative model is decreased when determination of model grows down.

Genes↗

PubMed2000

Sex determination by discriminant function analysis of the right tibia in the prehispanic population of the Canary Islands.

This study has been performed in order to define standards usable to determine the sex of prehispanic individuals from the Canary Islands from their skeletal remains. Osteometric information at the right tibia was obtained from 59 complete skeletons from Gran Canaria, housed in the Museo Canario (Las Palmas), 45 males and 14 females (this constitutes the totality of complete prehispanic skeletons known from Gran Canaria). The parameters measured were: tibial length, proximal and distal epiphyseal breadth, transverse and anteroposterior diameter, perimeter at the nutrition foramen levels and minimum shaft perimeter. These parameters were subjected to different SPSS discriminant function analysis, combining all of them, or only the proximal or distal ones, without tibial length, etc., in order to obtain functions usable even if only bone fragments are available. Transverse diameter, proximal epiphyseal breadth and minimum shaft perimeter showed the highest discriminant power. The functions obtained showed high average accuracies, ranging from 94.9 to 98.3%, with female accuracies of 100%. The functions obtained were further applied to a test prehispanic population (ten males and ten females) from El Hierro. Overall accuracies of the functions when applied to this population ranged from 65 to 94.7%, with female accuracies ranging 80% to 100%.

Atlantic Islands↗

PubMed1994

Persistent topographic quantitative EEG sequelae of chronic marihuana use: a replication study and initial discriminant function analysis.

In a previous pilot study using psychiatric patients we reported that daily marihuana users had significant elevations of (1) Absolute Alpha Power, (2) Relative Alpha Power, and (3) Interhemispheric Alpha Coherence over both frontal and frontal-central areas when contrasted with subjects who did not use marihuana. We referred to this phenomenon as Hyperfrontality of Alpha. The study presented here is a successful replication of our previous findings using new samples of subjects and identical methods. Post hoc analyses based on the combined sample from both studies suggest that variables of psychiatric diagnoses and medication did not bias our results. In addition, a discriminant function analysis using quantitative EEG variables as candidate predictors generated a 95% correct THC user versus nonuser classification accuracy which received a successful jackknife replication.

Adult↗

PubMed1982

Value of plasma calcium, phosphate, and alkaline phosphatase measurements in the diagnosis of histological osteomalacia.

Plasma calcium and phosphate concentrations and alkaline phosphatase activities were examined retrospectively in 50 patients with histologically proven osteomalacia and 50 age- and sex-matched control subjects with normal bone histology. An abnormal plasma alkaline phosphatase activity was more useful than an abnormal plasma calcium or phosphate concentration in distinguishing between normal and osteomalacic subjects, producing a false-negative rate of 14% and a false-positive rate of 8%. False-negative and false-positive rates of 10% and 8% respectively were obtained when the presence of an abnormality in any one of the three biochemical measurements was used as a predictor of histological osteomalacia. When discriminant analysis was applied to plasma calcium, phosphate and alkaline phosphatase together a false-negative rate of 12% and a false-positive rate of 0% was obtained.Sixty-two patients in whom a diagnosis of osteomalacia was suspected were investigated prospectively, using both single biochemical abnormalities and the classification functions derived from the discriminant analysis of all three biochemical measurements to predict the presence or absence of histological osteomalacia. Plasma alkaline phosphatase activity gave false-negative and false-positive rates of 10% and 32% respectively but was a more reliable predictor of abnormal bone histology than were plasma calcium or plasma phosphate concentrations or the presence of an abnormality in any one of the three measurements. Discriminant analysis using plasma calcium, phosphate and alkaline phosphatase together produced a false-negative rate of 16% and a false-positive rate of 10%. We conclude that plasma alkaline phosphatase activity is the best single routine biochemical screening test for osteomalacia, although a high false-positive rate may occur. Direct discriminant analysis of plasma calcium, phosphate and alkaline phosphatase together provides a more sensitive method of detecting histological osteomalacia which should be useful in determining the prevalence of osteomalacia within high-risk populations.

Adolescent↗

PubMed1993

In vitro characterization of lung cancers by the use of 1H nuclear magnetic resonance spectroscopy of tissue extracts and discriminant factor analysis.

Using proton magnetic resonance spectroscopy (1H MRS) spectra were obtained in vitro from extracts of four types of lung cancer (squamous cell, adenocarcinoma, large cell, small cell) and normal lung. The hydrophilic phase of the chloroform/methanol-water extracts yielded several distinct peaks. Among them the peak areas for cholines, creatines, glycine, and alanine, and their ratios were calculated and used as parameters to characterize different lung tissues. The ratios, cholines/alanine and glycine/alanine, were significantly (P < 0.001 to P < 0.05) higher for the normal lung than lung cancers. Creatines/glycine and creatines/cholines generally provided good discrimination (P < 0.001 to P < 0.05) between any two types of lung cancer. When data were further analyzed by discriminant factor analysis, there was 81.5 to 90.7% accuracy in predicting between normal lung and each cancer type, or among the four types of lung cancer. These results suggested that 1H MRS might be useful as an adjunct modality in the differential diagnosis of lung cancers.

Adenocarcinoma↗