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PubMed1988

Diabetic autonomic neuropathy--Part I. Autonomic nervous system data analysis by a computerized central unit in a multicenter trial.

To determine the feasibility of utilizing a central, computerized unit to analyze autonomic nervous system function tests for a 10-year, multicenter, clinical trial, the Autonomic Nervous System Reading Center was established. The Reading Center selected and standardized testing methods, designed the testing protocol, developed testing equipment, computerized data analysis, and instituted measures to monitor data quality. Three cardiovascular testing methods, RR-variation, Valsalva maneuver, and postural testing, were selected because each is a simple, non-invasive, quantitative, sensitive, and reproducible test. Furthermore, a hierarchy of sensitivity has been established with these cardiovascular autonomic nervous system measurements: RR-variation, Valsalva maneuver, and finally postural testing. Confounding variables were minimized by prescribing eligibility criteria. Testing equipment, designed to record time between RR intervals in a form easily read into a computer, has been in 21 clinics for three years and a total of 54 technicians have been trained. Over 85 percent of the autonomic nervous system tests performed have been usable at initial testing. A central reading center is an efficient and necessary means of collecting and analyzing data for a multicenter clinical trial.

Autonomic Nervous System Diseases↗

PubMed1989

The effects of overhead transparency design on retention, recall, and application of data analysis content.

This experimental study tested the effects of overhead transparency design in conjunction with live lecture on retention, recall, and application of data analysis content over three occasions using a Solomon Four-Group, pretest-posttest design. Pretested subjects showed significant (p less than .001) gains in test scores from pre to posttest. No significant differences were found in pretest scores between control and experimental treatment groups or among the posttest scores of either the experimental or control groups.

Audiovisual Aids↗

PubMedDate not supplied

Multivariate data analysis in empirical research. A look on the bright side.

The interpretive benefits of employing multivariate analysis methods on experimental data with more than one dependent variable are described heuristically and illustrated on a set of data from a simply designed experiment in physiological psychology. Multivariate analysis of variance (MANOVA) is performed on the 9 dependent variables contained in the sample data and on the four composites derived from a principal components analysis (PCA) of the variability of the nine. A linear discriminant analysis (LDA) is conducted following both MANOVA results, and 5 methods of determining the "important" dependent variables in the experimental-control group difference are presented and discussed in terms of the data at hand.

Analysis of Variance↗

PubMed1979

HLA-D typing with lymphoblastoid cell lines. VII. A computer program for data analysis.

When lymphoblastoid cell lines (LCL) are substituted for peripheral blood lymphocytes from human typing cell donors in HLA-D typing experiments, a data analysis program must be designed to distinguish the effect of allo-reactivity from those peculiar to LCL, mainly the "autologous-stimulation" effect. The computer program described in this report was created specifically for such an analysis. The rationale for the design of this program is presented in the preceding report (see this issue).

Cell Line↗

PubMed1978

[Planning and data analysis in prospective controlled clinical trials (author's transl)].

Planning of prospective controlled clinical trials in surgery requires the use of test and control groups, sufficiently frequent repetition of experiments, random allocation of patients to the groups (example), and balancing. The descriptive data analysis should be performed in a stepwise manner (list of new data, rank list, range, median, quartiles, histogram, mean value standard deviation). The advantages of the median-quartile-system and the prerequisites for application of various significance tests are pointed out. In the conduct of controlled clinical trials, the consultative role of experimental surgeons is proposed.

Clinical Trials as Topic↗

PubMed1989

Histopathological classification of dementias by multivariate data analysis.

Autopsied brains from 55 demented patients, clinically classified according to DSM-III criteria into AD/SDAT and MID and 19 nondemented individuals were available for this study. Using general clinical, gross neuroanatomical and histopathological data three separate dementia classes, namely AD/SDAT, MID and AD-MID, were visualized in two-dimensional space by multivariate data analysis. This analysis revealed that the pathology in AD-MID patients were not merely a linear combination of the pathology in AD/SDAT and MID, indicating that AD-MID might represent a dementia type of its own.

Aged↗

PubMed1992

Clinical assessment of the knowledge base of an expert system for data analysis in laboratory medicine.

Despite the apparent demand for a consultation system, only a few expert systems have been developed for laboratory medicine. Some studies on the diagnostic precision of such systems have been reported, but the efficiency of their knowledge bases has not yet been investigated. An expert system, named BLOOD, for data analysis in a hematology laboratory, which is written in C-Prolog and runs on VAX-station, has already been reported to have excellent diagnostic reliability and ability to cope with the fuzziness involved in clinical diagnostic procedures. A quantitative examination of the knowledge base of BLOOD using real laboratory data from 58 patients diagnosed as having iron deficiency anemia clearly revealed the verbosity of the knowledge base, and proved that it was effective for obtaining a group of essential diagnostic rules.

Anemia, Hypochromic↗

PubMed1988

Precision in calculated rho, T1 and T2 images as a function of data analysis method.

In NMR imaging rho, T1 and T2 images are usually calculated from a set of partial saturation, saturation recovery or inversion recovery experiments with multiple echoes and multiple repetition times. Several methods can be envisaged to extract parameter images from such a set of source images. These methods to a greater or lesser extent take advantage of the fact that a multiple echo/multiple repetition time experiment provides a set of largely independent T1 and T2 measurements. In this study several data analysis methods, including weighted and non-weighted averaging of results of independent T1 and T2 measurements, weighted and non-weighted averaging of source images prior to data reduction and simultaneous three-parameter fitting, were compared against another in terms of precision, computational efficiency and robustness. The predicted performance of the examined methods was verified by stochastic simulation experiments.

Humans↗

PubMed2026

Novelty seeking and rapid symptom improvement across active and sham accelerated iTBS conditions: A pooled individual-patient data analysis.

INTRODUCTION: Major depressive disorder (MDD) is highly prevalent and often treatment-resistant. Accelerated intermittent theta burst stimulation (aiTBS) is a promising intervention for treatment-resistant depression (TRD), though outcomes vary. Personality traits have been examined in relation to rTMS outcomes, yet their role in aiTBS remains underexplored. This pooled individual-patient-data analysis of two randomized, sham-controlled trials examined associations between baseline Temperament and Character Inventory (TCI) traits and one-week symptom change, and whether they differed by condition. METHODS: The left dorsolateral prefrontal cortex was targeted for 20 sessions over 4 days. Personality was assessed with the TCI, depression severity with the 17-item Hamilton Depression Rating Scale (HDRS-17). TCI-symptom-change associations were examined with a robust linear mixed-effects model, adjusting for age, gender, repeated measurements, and study membership. RESULTS: 104 participants were included (M/F 45/59; mean age 40.9 ± 12.7; active/sham 50/54). The model yielded a Time × Novelty Seeking interaction (β = -1.70, p = 0.021): higher baseline Novelty Seeking was associated with faster symptom reduction, without a between-arm difference. However, the interaction did not survive Holm correction across 14 trait-interaction tests (adjusted p = 0.294) and is therefore exploratory. No other interaction reached the uncorrected threshold. CONCLUSIONS: Higher baseline Novelty Seeking showed a nominal association with faster symptom reduction, without a difference between active and sham conditions. Because it did not survive multiplicity correction and was not reproduced in within-arm analyses, it is preliminary and may reflect contextual or nonspecific processes. Independent replication is required before temperament assessment can be clinically informative.

Humans↗

PubMed1991

A regularity statistic for medical data analysis.

A new statistic has been developed to quantify the amount of regularity in data. This statistic, ApEn (approximate entropy), appears to have potential application throughout medicine, notably in electrocardiogram and related heart rate data analyses and in the analysis of endocrine hormone release pulsatility. The focus of this article is ApEn. We commence with a simple example of what we are trying to discern. We then discuss exact regularity statistics and practical difficulties of using them in data analysis. The mathematic formula development for ApEn concludes the Solution section. We next discuss the two key input requirements, followed by an account of a pilot study successfully applying ApEn to neonatal heart rate analysis. We conclude with the important topic of ApEn as a relative (not absolute) measure, potential applications, and some caveats about appropriate usage of ApEn. Appendix A provides example ApEn and entropy computations to develop intuition about these measures. Appendix B contains a Fortran program for computing ApEn. This article can be read from at least three viewpoints. The practitioner who wishes to use a "black box" to measure regularity should concentrate on the exact formula, choices for the two input variables, potential applications, and caveats about appropriate usage. The physician who wishes to apply ApEn to heart rate analysis should particularly note the pilot study discussion. The more mathematically inclined reader will benefit from discussions of the relative (comparative) property of ApEn and from Appendix A.

Algorithms↗

PubMed1987

Signal peptide amino acid sequences in Escherichia coli contain information related to final protein localization. A multivariate data analysis.

With few exceptions, the signal peptides from proteins inserted into, or translocated through, the membranes of gram-negative bacteria or the endoplasmic reticulum of eukaryotes have no sequence homologies. Therefore these signal peptides have not been considered to contain information related to the different final localizations of the proteins. In this study, 43 signal peptide amino acid sequences from proteins with different final localizations in Escherichia coli have been subjected to a multivariate data analysis. Each amino acid residue was characterized by 20 physico-chemical properties, yielding a multivariate property profile for each peptide. The similarities/dissimilarities in the property profiles for the signal peptides from different classes were compared with each other by generating few-dimensional partial least squares (PLS) discriminant plots. With this approach, signal peptides from proteins localized to the periplasmic space (PS), the outer membrane (OM), and the extracellular surroundings (excreted proteins), were separated into distinct groups. Signal peptides from pili proteins were not separated from the OM signal peptides and only partly from the PS signal peptides, but were clearly different from the signal peptides of the excreted proteins. Signal peptides from inner membrane proteins were similar to those of the PS peptides. The size and the hydrophobicity of different peptide segments were responsible for the separation of the signal peptide classes. For example, the hydrophobicity of the N-terminal segment of the signal peptides increased with an increased distance from the cytoplasm of the final localization for the corresponding proteins. Thus, many signal peptides from proteins with different final localizations in E. coli have different discernible physico-chemical profiles.

Amino Acid Sequence↗

PubMed1977

[Improvement of resolution of positron annihilation radiation energy spectrum measurement by data analysis (author's transl)].

Recently much attention is being paid to positron annihilation radiation energy spectrum measurement as a simple method that gives information about the momentum distribution of an annihilating pair. However, this method has a disadvantage that it is sensitive to drifts of the measuring system and the resolution is still insufficient. We have succeeded to reduce the influence of the drifts to a negligibly small degree by using, in addition to the necessary procedure for a temperature control and stabilizing of AC power lines, a compensation technique in data analysis. We have further attempted to improve the resolution by deconvolution processing. By these procedures, we have been able to separate a narrow component which has not otherwise been resolved directly from the spectrum. The resolution attained by this way is 0.43 keV (FWHM), and is two- or three-fold superior to those ever reported.

Models, Theoretical↗

PubMed1989

Some practical issues of experimental design and data analysis in radiological ROC studies.

Receiver operating characteristic (ROC) analysis has been used in a broad variety of medical imaging studies during the past 15 years, and its advantages over more traditional measures of diagnostic performance are now clearly established. But despite the essential simplicity of the approach, workers in the field often find--sometimes only after an ROC study is under way--that a number of subtle issues related to experimental design and data analysis must be confronted in practice. Many of these issues have not been discussed in the literature in detail, and most are not well known. The purposes of this paper are to make users of ROC methodology in medical imaging aware of potential problems that should be confronted before an ROC study is begun and to indicate, at least broadly, how those problems may be dealt with, given the present state of the art. Some of the issues raised here can be addressed adequately by easily prescribed techniques, whereas others remain difficult and will be resolved fully only by new methodologic developments.

ROC Curve↗

PubMed1987

Prevalence survey of infection in a Hong Kong hospital using a standard protocol and microcomputer data analysis.

A 1-day prevalence survey of hospital infection was performed in June 1985 at a new general teaching hospital in Hong Kong. The 1980 British national survey protocol was used, and the results were analysed by microcomputer. The major part of the survey was carried out by nine people over a period of 3 days and was completed within 6 weeks. The rate of hospital-acquired infection was 8.9% and of community-acquired infection was 16.5%. Antibiotics were mainly used in infected patients. The British protocol is suitable for Hong Kong hospitals, and with microcomputer data analysis such surveys can be completed quickly and accurately even with limited resources.

Adolescent↗

PubMed1977

Physiological consequences of experimental cerebral missile injury and use of data analysis to predict survival.

The authors describe cerebrovascular and cerebral metabolic changes in monkeys, subjected to cerebral missile injury. After injury with BB pellet at 90 m/sec, there is a rapid rise in intracranial pressure (ICP), which reaches a peak 2 to 5 minutes posttrauma, and then falls to about 20 to 30 mm Hg. This, with a fall in mean blood pressure (MBP), results in a 50% reduction in cerebral perfusion pressure (CPP), Cerebral blood flow (CBF) is also reduced, although acutely there is no close relationship with (CPP). Cerebrovascular resistance falls initially and then at 30 minutes rises to very high values. Cerebral metabolic rates (CMR's) for oxygen fall after injury and remain low for the rest of the animal's life; CMR's for lactate rise immediately after injury and persists for 5 hours, then fall. After injury with a faster missile (180 m/sec), the ICP rises higher and faster, and the peak is shorter. The CCP is reduced in this injury to approximately 30 mm Hg, and only one animal survived more than 1 hour. With the conventional forms of data analysis, the length of survival after injury correlates well with MBP, ICP, and CBF, but separately they were completely unsatisfactory for prediction of an individuals prognosis. With the technique of multiple linear regression analysis, the survival of individual animals could be predicted with great accuracy. This is possible also when two postinjury parameters,CBF and MBP, are used.

Animals↗

PubMed1986

An improved data analysis method for interleukin 2 microassay.

Development of the interleukin 2(IL 2) microassay, coupled with the use of highly purified or recombinant factors has allowed a detailed examination of the mechanism of action of this important biological response modifier. However, probit analysis of the microassay data does not allow inherent error of the system to be approximated nor can units of activity be assessed for significance. A computer program was developed to analyze the validity of each regression line and to generate 95% confidence intervals around each line. This program employs analysis of variance, linear regression analysis and the parallel line assay to fix confidence intervals for each IL 2 unit value. The use of recombinant IL 2 as an immunomodulator in clinical settings warrants a more precise statistical method to evaluate normal fluctuations of this factor than currently in use. The development of such a method is presented here.

Biological Assay↗

PubMed1987

On multiparameter data analysis in flow cytometry.

Increasing numbers of parameters that are accessible to simultaneous measurement in flow cytometric instruments, combined with the extremely large sample sizes common in flow cytometry, make it necessary to examine methods of multivariate statistics for their applicability to problems of visualization and quantitative analysis of flow cytometric data. This article describes some approaches to dimensionality reduction that appear well suited for data sets obtained by flow cytometry.

Flow Cytometry↗

PubMed2026

Vancomycin Effectiveness in Reducing Surgical Site Infection in Posterior Spinal Fusion Surgery: A Retrospective Data Analysis of the STRIVE Trial.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: To re-evaluate vancomycin as a preventive measure for surgical site infection (SSI). SUMMARY OF BACKGROUND DATA: Intrawound vancomycin powder is used to prevent SSIs in spinal surgery. Prior studies, often limited to single institutions or small samples, have shown mixed efficacy and potential increases in non- S. aureus and Gram-negative infections. We hypothesized that SSIs rates would be similar with and without intrawound vancomycin in posterior spinal fusion (PSF) surgery. METHODS: Prospectively collected data from the 3595 patients in the STaphylococcus aureus suRgical Inpatient Vaccine Efficacy (STRIVE) trial were stratified by intrawound antibiotic usage. Multivariate logistic regression assessed the effect of vancomycin use on SSI, adjusting for patient demographics and SSI-associated risk factors. Secondary outcomes included critical care stay, reoperation, sepsis, and hospital readmission. RESULTS: Of 3311 patients who underwent surgery, 847 (26%) received only intrawound vancomycin and 1534 (46%) received no intrawound antibiotics. Sixty (8%) patients developed postoperative SSI, of whom 20 (33%) had received intrawound vancomycin. Receiving intrawound vancomycin was not associated with SSI incidence versus no intrawound antibiotics [odds ratio (OR): 0.77; 95% CI: 0.42-1.42], critical care stay (OR: 0.94; 95% CI: 0.78-1.12), or sepsis (OR: 2.04; 95% CI: 0.62-6.73). However, intrawound vancomycin was associated with increased odds of hospital readmission (OR: 1.82; 95% CI: 1.28-2.6; P < 0.001) and reoperation (OR: 1.75; 95% CI: 1.18-2.6; P = 0.005). Factors significantly associated with intrawound vancomycin use included intraoperative antibiotic readministration (OR: 2.97; 95% CI: 1.36-6.5; P =0.006) and hospital location, lower odds in Europe (OR: 0.13; 95% CI: 0.06-0.29; P < 0.001) or Asia (OR: 0.02; 95% CI: 0-0.08; P < 0.001) versus North America. CONCLUSIONS: Intraoperative vancomycin use was not associated with reduced SSI incidence compared with no intrawound antibiotics after PSF surgery. LEVEL OF EVIDENCE: Level II.

Humans↗