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PubMed1998

Morphometric multivariate analysis of field samples of adult Anopheles arabiensis and An. gambiae s.s. (Diptera: Culicidae).

The Afrotropical complex of sibling species Anopheles gambiae Giles includes the most efficient vectors of human malaria south of the Sahara. Anopheles arabiensis Patton and An. gambiae s.s. Giles are the members of the complex more adapted to the human environment. They are sympatric and synchronic over most of their distribution range; however, they show a different involvement in malaria transmission, with An. gambiae being more anthropophilic and endophilic than An. arabiensis. Discriminating between them is essential for a correct assessment of epidemiological parameters. The identification is currently achieved through recognition of species-specific chromosomal inversions or by molecular biology techniques. Both methods require considerable technical resources, not always available in the field. We carried out a morphometric analysis of field and laboratory samples of An. arabiensis and An. gambiae s.s. from sites in Madagascar, Burkina Faso, Mali, and Liberia to evaluate the degree of morphological differentiation. We examined 17 morphometric characters in samples representing each of the geographic sites. All of the measures were significantly larger for An. arabiensis (regardless of the collection site), demonstrating an intrinsic greater body size of this species. To assess the reliability associated with the multivariate statistic, we applied the discriminant function analysis, which provided a method for predicting to which group a new case will most likely be assigned. In a blind experiment, the morphometric method correctly identified approximately 85% of field-collected An. arabiensis and An. gambiae s.s., which provided a relatively simple method to approximate the relative frequencies of the 2 species in areas in which their concurrent presence was already known. The influence of laboratory conditions on the morphometrics of the 2 species was also analyzed.

Animals↗
PubMed1982

Multivariate analysis of smoking and other risk factors for obstructive lung diseases and related symptoms.

Multivariate analyses of the relationship of risk factors and respiratory symptomatology in a longitudinal epidemiologic study of airways obstructive disease in a white community population has yielded some consistent findings. Diagnosed airway obstructive diseases and functional impairment appear to be related to a set of risk factors which include age, smoking, a history of acute respiratory illness, chronic cough and phlegm, and to some extent, social status, occupational exposures, and alcohol consumption. Smoking definitely appears to be related to productive cough. It also appears to be related, though not necessarily directly, to AOD and lung function impairment. The complexity of the relationships were clarified by the analysis using multivariate techniques.

Adolescent↗
PubMed2000

Role of clinical, radiological, and neurophysiological changes in predicting the outcome of tuberculous meningitis: a multivariable analysis.

OBJECTIVES: The role of EEG and evoked potentials has not been evaluated in predicting the prognosis of tuberculous (TB) meningitis. The present study was aimed at evaluating the prognostic significance of clinical, radiological, and neurophysiological variables using multi-variable analysis. METHODS: Patients with TB meningitis diagnosed on the basis of clinical, radiological, and CSF criteria have been prospectively evaluated. All the patients were subjected to a detailed neurological evaluation. The outcome was defined 6 months after starting treatment on the basis of the Barthel index (BI) score into poor (BI <12) and good recovery (BI> or =12). Death was included in the poor recovery group for statistical analysis. Thirteen clinical (age, sex, seizure, focal weakness, stage of meningitis, Glasgow coma scale score, methyl prednisolone therapy), CT (infarction, hydrocephalus, tuberculoma) and neurophysiological (EEG, motor and somatosensory evoked potentials) variables were evaluated employing single variable logistic regression followed by multivariable logistic regression analysis. The best set of predictors were obtained by stepdown logistic regression analysis. RESULTS: Fifty four patients were included in the present study. Their age ranged between 5 and 62 years, 11 were children younger than 12 years and 14 were female. Nine patients were in stage I meningitis, 12 in stage II, and 33 in stage III. On single variable logistic regression analysis the significant predictors of 6 months outcome of TB meningitis included focal weakness, Glasgow coma scale (GCS), motor evoked potential (MEP) and somatosensory evoked potential (SEP). On multivariable analysis the best set of predictors comprised focal weakness, GCS, and SEP. CONCLUSIONS: In patients with TB meningitis focal weakness, GCS, and SEP are the best predictors of 6 month outcome.

Adolescent↗
PubMed2004

Multivariate analysis of the selectivity for a pentachlorophenol-imprinted polymer.

A pentachlorophenol (PCP)-imprinted polymer (MIP) was obtained by thermal polymerization of a mixture of template, 4-vinylpyridine and ethylene glycol dimethacrylate with molar ratio 1 +3 + 27, using as porogenic solvent methanol-water ( 3 + 1(v/v)). The polymer was packed in an HPLC column and selectivity towards 52 PCP-related phenols (22-chloro-, 21-alkyl-, 4-aryl-, 3-methoxy- and 6-polyphenols) was measured using acetonitrile-acetic acid (99 + 1(v/v)) as mobile phase. The same was made for a reference polymer obtained without pentachlorophenol (NIP). The molecular recognition properties of the imprinted polymer were expressed in terms of selectivity index (SI), calculated for each phenol as k(NIP)/k(MIP). Sixteen molecular descriptors were calculated for each molecule: qO, the partial charge of the phenolic oxygen atom; qH, the partial charge of the phenolic hydrogen atom; Deltaq, the absolute value of the difference qO - qH; HOMO, the highest occupied molecular orbital; LUMO, the lowest unoccupied molecular orbital; Deltaorb, absolute value of the difference HOMO - LUMO; micro(2), the square of total dipole moment; MW, the molecular weight; SAS, the solvent-accessible molecular surface area; hSAS, the hydrophobic solvent-accessible molecular surface area; Svdw, the van der Waals molecular surface area; hSvdw, the hydrophobic part of Svdw; MOv, the molecular ovality; RG, the radius of gyration; logP, the logarithm of n-octanol-water partition coefficient; pK, the phenolic dissociation constant. Correlations between selectivity index and these descriptors were searched utilizing multivariate principal component analysis (PCA). The multivariate model obtained by regression on the principal components correlate collectively several of the calculated descriptors with the polymer selectivity. The magnitude of the model's parameters shows that selectivity is strongly influenced by molecular descriptors having structural character, such as MW, hSvdw and logP, while the effect of molecular descriptors having electronic character, such as qO and pK, is much less marked.

Multivariate Analysis↗
PubMed2000

Multivariate analysis and quantitation of (17)O-nuclear magnetic resonance in primary alcohol mixtures.

Multivariate techniques were used to address the quantification of (17)O-nuclear magnetic resonance (NMR) spectra for a series of primary alcohol mixtures. Due to highly overlapping resonances, quantitative spectral evaluation using standard integration and deconvolution techniques proved difficult. Multivariate evaluation of the (17)O-NMR spectral data obtained for 26 mixtures of five primary alcohols demonstrated that obtaining information about spectral overlap and interferences allowed the development of more accurate models. Initial partial least squares (PLS) models developed for the (17)O-NMR data collected from the primary alcohol mixtures resulted in very poor precision, with signal overlap between the different chemical species suspected of being the primary contributor to the error. To directly evaluate the question of spectral overlap in these alcohol mixtures, net analyte signal (NAS) analyses were performed. The NAS results indicate that alcohols with similar chain lengths produced severely overlapping (17)O-NMR resonances. Grouping the alcohols based on chain length allowed more accurate and robust calibration models to be developed.

1-Butanol↗
PubMed1999

Multivariate analysis of superficial scald susceptibility on Granny Smith apples dipped with different postharvest treatments.

Multivariate methods were used to present the results of different postharvest treatments applied to control superficial scald disorder in Granny Smith apples. In a two-season study, the treatments applied by dips were diphenylamine (DPA), Semperfresh (a sucrose ester coating) formulated alone or with either ascorbyl palmitate or n-propyl gallate, and CaCl(2). DPA correlated negatively with scald, whereas the rest of the treatments showed no clear relationship with the disorder. By means of partial least squares, the incidence of superficial scald after cold storage was shown to correlate with quality parameters (firmness and acidity), measured at the end of storage. In contrast, ethylene production did not appear as a relevant factor in the incidence of scald.

Cold Temperature↗
PubMed2004

Is survival following post-operative radiotherapy in pN1-non-small cell lung cancer reduced? Results of a multivariate analysis.

Prognostic factors and the role of post-operative radiotherapy (PORT) in patients with pN1 nodal stage following surgery for NSCLC were identified. The clinical course of 211 patients with pN1 nodal involvement following thoracic surgery were reviewed, 97 of them received PORT. Multi-variate survival analysis with respect to prognostic factors (including treatment) was performed. The most frequent site of recurrence was the ipsilateral bronchus-stump or hilus (63% of recurrences). The 5-year rate of intercurrent deaths for PORT was 1% vs 6% in the group without PORT. The 5-year rate of locoregional recurrence was similar (24% vs 19%) for PORT vs no PORT (p=0.97). PORT patients had a higher rate of distant metastases (p=0.04). The 5-year rate of overall survival was 45% without PORT and 25% with PORT (p=0.003). Multivariate survival analysis identified 4 prognostic factors associated with decreased survival rate: age, extended pneumectomy, number of involved nodes and PORT dose. A PORT dose of 50 Gy corresponds to an increase in relative risk of death in the range of 1.5. Patients with PORT do not have an increased rate of intercurrent deaths. However in this cohort, PORT in pN1 patients was associated with a decreased survival rate due to distant metastases. Even after correction with respect to accepted prognostic factors in multivariate survival analysis, PORT was not able to improve or equalize prognosis of these negatively selected patients. The main site of recurrence is the bronchial stump and hilus. If PORT is applied in pN1 patients, a reduction of the target volume should be discussed since local control in high-risk patients may be of relevance.

Age Factors↗
PubMed1994

Varying grades of epithelial atypia in the pancreatic ducts of humans. Classification based on morphometry and multivariate analysis and correlated with positive reactions of carcinoembryonic antigen.

To establish an adequate statistical classification of epithelial atypia in the pancreatic duct, a total of 78 areas of duct epithelia with varying grades of atypia were subjected to nine-parameter morphometry and nine-dimensional multivariate cluster analysis. The material was derived from 53 pancreases resected for various epithelial tumors or acute or chronic pancreatitis. The result was correlated with immunohistochemical findings in which the pattern of intraepithelial distribution of carcinoembryonic antigen changed with the degree of ductal atypia. Finally, atypical cells classified by cluster analysis and immunohistochemistry were subjected to computer-aided three-dimensional mapping to visualize their distribution in the ductal tree. Cluster analysis demonstrated that the various epithelial forms were classifiable into Clusters 1, 2, and 3, representing ordinary epithelia and mild and severe dysplasias, respectively. The last category was created so as to include not only in situ and invasive carcinoma but the so-called borderline atypical lesions. The reproducibility of this classification was proved by two sorts of discriminant analyses. Also, the grades of atypia shown by the clustering proved to correlate with the reaction patterns for carcinoembryonic antigen. In the computer-aided three-dimensional mapping, severely dysplastic areas were shown surrounded by zones of mild dysplasia, justifying the assumption of a stepwise carcinogenesis in the pancreatic ducts.

Carcinoembryonic Antigen↗
PubMed1999

Preoperative assessment of mortality risk in hepatic resection by clinical variables: a multivariate analysis.

Hepatic resection is a chance for cure for primary and secondary liver tumors and a variety of benign diseases. Despite advances in surgical technique and patient care, preoperative and postoperative morbidity in patients undergoing liver resection remains high. Because a high morbidity represents a risk factor contributing to a fatal outcome of the surgical procedure, our study aimed to investigate the contribution of different risk factors to a fatal outcome and if mortality can be predicted by the presence of certain risk factors. Two hundred fifty-seven patients undergoing hepatic resection (curative and palliative) were analyzed preoperatively, immediately after surgery, and 10 days after surgery for 60 potential risk factors. Survivors (n = 238) and nonsurvivors (n = 19) were compared univariately. The analysis identified 14 variables to differentiate between groups. These variables were processed by multivariate logistic regression analysis. Three models to estimate 30-day mortality were identified, tested for statistical accuracy, and assessed for their receiver-operated characteristics (ROCs). The variables in the multivariate models were as follows: preoperatively, age, number of comorbid factors, and presence of cirrhosis; immediately after surgery, age, number of comorbid factors, and percentage of resected liver; and 10 days after surgery, age, hours of ventilation, and number of adverse events. Goodness of fit was 0. 863, 0.912, and 0.966, respectively. Areas under the ROC curves were 83.6%, 85.7%, and 98.0%. The specificity (probability to identify survivors correctly) was greater than 90% for all models, although sensitivity (probability to identify nonsurvivors correctly) was greater than 90% only for 10 days after surgery. We conclude that logistic regression is appropriate to assess the importance of risk factors in the course of hepatic resection and to identify patient groups at high risk.

Female↗
PubMed1985

Results of treatment in patients with end-stage renal disease: a multivariate analysis of risk factors and survival in 341 successive patients.

Factors that affect survival in patients with end-stage renal disease (ESRD) are still only partially understood. We report an analysis on a cohort of 341 successive patients who started ESRD treatment in one institution. Survival was calculated from the start of ESRD treatment, whether initial treatment was by dialysis (335 patients) or transplantation (6 patients). Analysis of factors affecting survival was done using the Cox multivariate hazard analysis. Relative risks were calculated for several demographic factors, the primary renal disease, the presence or absence of various high-risk co-morbid factors, and for a first transplant from a living-related or cadaver donor. Older patients, patients with no prior health insurance, those with diabetic nephropathy, and those with small kidneys of unknown cause had statistically significantly higher risks of dying. The risk of dying decreased by year of start of ESRD treatment. Living related donor transplantation was associated with a decreased hazard to age 45 years and older; whereas cadaver donor transplantation was associated with a hazard that increased with age and was significantly increased by age 45.

Actuarial Analysis↗
PubMed1998

Caring in nursing: a multivariate analysis.

The dimensions underlying the perceptions of caring among nurses were investigated using the Edinburgh Caring Dimensions Inventory (CDI). Exploratory and confirmatory factor analysis techniques were used. While there was a general caring factor on which the majority of the items in the CDI loaded, there were two separable major dimensions to caring, namely 'psychosocial aspects' and 'professional and technical aspects'. In addition, two smaller dimensions were identified that were both related to self-giving, and it is postulated that these refer, respectively, to appropriate and inappropriate self-giving in nursing.

Adult↗
PubMed2001

Identification of Enterococcus, Streptococcus, and Staphylococcus by multivariate analysis of proton magnetic resonance spectroscopic data from plate cultures.

A new fingerprinting technique with the potential for rapid identification of bacteria was developed by combining proton magnetic resonance spectroscopy ((1)H MRS) with multivariate statistical analysis. This resulted in an objective identification strategy for common clinical isolates belonging to the bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, and the Streptococcus milleri group. Duplicate cultures of 104 different isolates were examined one or more times using (1)H MRS. A total of 312 cultures were examined. An optimized classifier was developed using a bootstrapping process and a seven-group linear discriminant analysis to provide objective classification of the spectra. Identification of isolates was based on consistent high-probability classification of spectra from duplicate cultures and achieved 92% agreement with conventional methods of identification. Fewer than 1% of isolates were identified incorrectly. Identification of the remaining 7% of isolates was defined as indeterminate.

Culture Media↗
PubMed1992

Fused eyelids in the extremely premature infant: multivariate analysis of survival and outcome.

The presence of fused eyelids at birth in the extremely low birthweight infant (less than 1000 gm) is often regarded by physicians as an indication of nonviability. This is especially true for the pediatrician who does not have routine exposure to extremely premature infants and may use the presence of fused eyelids to influence the level of resuscitation afforded the infant in the first crucial minutes following birth. Unfortunately, there are scant data in the literature to guide general pediatricians with regard to this issue. The purpose of this study was to examine, with the aid of multivariate statistical analysis, the survival and combined outcome score in extremely premature infants with and without fused eyelids. The combined outcome was a composite of several outcome variables (intraventricular hemorrhage, bronchopulmonary dysplesia, and retinopathy of prematurity); survival was defined employing the standard definition of neonatal survival, that is, alive at 28 days post natal age. Combined outcome and survival were analyzed with regard to several independent variables (birthweight, gestational age, and 5-minute Apgar scores, mode of delivery, race, sex, and maternal age). A regression analysis was performed to determine the effect of the independent variables on the combined outcome. A separate multivariate logistic regression analysis was employed to determine the effect of the same independent variables on neonatal survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1999

Outcome of Budd-Chiari syndrome: a multivariate analysis of factors related to survival including surgical portosystemic shunting.

The aim of this study was to assess the factors, including surgical portosystemic shunts, which affect survival in adults with Budd-Chiari syndrome. Multivariate retrospective analysis was performed using characteristics recorded at the time of diagnosis in 120 patients admitted from 1970 to 1992, of whom 82 were treated with surgical portosystemic shunts and 38 received only medical therapy. The 1-, 5-, and 10-year survival rates were 77 +/- 4%, 64 +/- 5%, and 57 +/- 6%, respectively. Survival was significantly better in the subgroup of patients diagnosed after versus before 1985. In both subgroups, and in patients with, as well as in patients without surgical shunts, 4 factors were found to be inversely and independently related to survival: age, response of ascites to diuretics, Pugh score, and serum creatinine. In patients diagnosed since 1985, an index combining these 4 factors allowed to differentiate patients with a good outcome (5-year survival 95%) from those with a poor outcome (5-year survival 62%; P <.05). There was no statistically significant and independent influence of surgical portosystemic shunts on survival. In conclusion, age, severity of liver failure, and presence of refractory ascites are the main prognostic factors in Budd-Chiari syndrome. Increased survival in recent years is consistent with improved management of hypercoagulable states as well as improved general care. It is uncertain whether surgical portosystemic shunting favorably modifies survival. Therefore, we recommend that surgical shunting should be restricted to management of refractory ascites or variceal bleeding in patients with otherwise good prognostic factors.

Adolescent↗
PubMed1999

Low-grade stage III-IV follicular lymphoma: multivariate analysis of prognostic factors in 484 patients--a study of the groupe d'Etude des lymphomes de l'Adulte.

PURPOSE: To identify the prognostic factors that influence overall survival (OS) in patients with stage III-IV follicular lymphomas and evaluate the clinical usefulness and the prognostic value of the International Prognostic Index (IPI). PATIENTS AND METHODS: Four hundred eighty-four patients with Ann Arbor stage III-IV follicular lymphomas treated in two phase III trials from 1986 to 1995 were screened for this study. All histologic slides were reviewed by two hematopathologists. The influence of the initial parameters on survival was defined by univariate (log-rank test) and multivariate (Cox model) analyses. RESULTS: The poor prognostic factors for OS (age > 60 years, "B" symptom(s), > or = two extranodal sites, stage IV disease, tumor bulk > 7 cm, at least three nodal sites > 3 cm, liver involvement, serous effusion-compression or orbital/epidural involvement, and erythrocyte sedimentation rate > 30 mm/h) that were significant in univariate analysis were subjected to multivariate analysis. Three factors remained significant: B symptom(s) (risk ratio = 1.80), age greater than 60 years (risk ratio = 1.60), and at least three nodal sites greater than 3 cm (risk ratio = 1.71). When the IPI was applied to these patients, the score was 1, 2, 3, and 4-5 in 49%, 39%, 11%, and 2%, respectively, and it was significant for progression-free survival (P =.002) and OS (P =.0001). CONCLUSION: Three prognostic factors for poor OS were identified: B symptoms, age greater than 60 years, and at least three nodal sites greater than 3 cm. The IPI was prognostic for OS, but in this population, a very low number of patients belonged to the high-risk groups.

Adult↗
PubMed1990

Surgery for soft tissue sarcoma in the extremities. A multivariate analysis of the 6-26-year prognosis in 137 patients.

In 137 patients with soft tissue sarcomas in the extremities, the influence of patient and tumor characteristics and surgical procedures on prognosis was studied using a multivariate statistical analysis. The minimum follow-up time was 6 years, and no patient was lost to follow-up. Eighty-nine patients were referred with the tumor intact (primary series), while 48 were referred after biopsy or with local recurrence after previous surgery (secondary series). The frequency of amputation was 15 percent in the primary series and 48 percent in the secondary series. A local, function-preserving operation with a wide margin was performed in 37 patients without biopsy (clinical diagnosis alone). Local control of the disease was obtained in all but one of these patients without any adjunctive treatment. Independent, unfavorable factors concerning local recurrence were advancing age, open biopsy, and marginal surgery. Independent, unfavorable factors concerning survival were advancing age, increasing histologic malignancy grade, and ablative surgery. A tumor-related death was observed in 0, 29, 47, and 67 percent of the patients with tumors of malignancy grades I, II, III, and IV, respectively.

Adolescent↗
PubMed1990

Value of serum acute-phase reactant proteins and carcinoembryonic antigen in the preoperative staging of colorectal cancer. A multivariate analysis.

In 55 patients with benign or malignant neoplasias of the large bowel, serum carcinoembryonic antigen (CEA), C-reactive protein (CRP), alpha 1-antitrypsin (AAT), alpha 1-acid glycoprotein (AAG) levels, and the percentage of serum protein electrophoretic components were measured. Statistical analysis showed significant correlations between serum CEA, CRP, AAG, and AAT levels and the percentage of serum beta-globulins with the stage of the disease. Multivariate discriminant analysis gave a final prognostic model that included serum CEA, CRP, and AAT levels and the percentage of the serum beta-globulins with a significance of P less than 0.000001. The authors conclude that the serum acute-phase protein levels, in combination with serum CEA concentrations, have a definite role in the preoperative staging of large bowel cancer.

Acute-Phase Proteins↗