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At least 577 records · Page 32Linked to original sources
PubMed2000

A comparison of diagnostic interviews for depression in the Stirling County study: challenges for psychiatric epidemiology.

BACKGROUND: High prevalence rates in psychiatric epidemiologic studies raise questions about whether data-gathering procedures identify transient responses rather than clinical disorders. This issue is explored relevant to depression using data from the Stirling County Study. METHODS: The study's customary method, the DPAX (DP for depression and AX for anxiety) was compared with the Diagnostic Interview Schedule (DIS), both of which were administered to a sample of 1396 subjects selected in 1992. Reasons for discordance were analyzed, and demographic correlates of responses to questions about dysphoria were examined. These lay-administered interviews were then compared with clinician-administered interviews that used the Structured Clinical Interview for DSM-III-R (SCID) with 139 subjects. The kappa statistic and logistic regression were used for statistical assessment. RESULTS: For the level of agreement between the DPAX and the DIS for current and lifetime depression, kappa = 0.40 and kappa = 0.33, respectively. Subjects diagnosed only by the DPAX tended to have less education than those diagnosed only by the DIS. Some idioms for dysphoria seemed to work better than others. Using SCID interviews as a clinical standard, the DPAX had 15% sensitivity and 96% specificity and the DIS had 25% sensitivity and 98% specificity. CONCLUSIONS: Comprehension of an interview can be improved by using multiple questions for dysphoria and a simpler mode of inquiry. Clinician-administered interviews tend to corroborate disorders identified in lay-administered interviews but suggest that survey methods underestimate prevalence. Further research is needed to evaluate the validity of both types of interviews, but evidence from a 16-year follow-up evaluation indicates that depression diagnosed by the DPAX is a serious disorder in terms of morbidity and mortality.

Adult↗
PubMed2006

Development and validation of handy rheumatoid activity score with 38 joints (HRAS38) in rheumatoid arthritis patients receiving infliximab.

The parameters involved in the Disease Activity Score of 28 joints (DAS28) are not mutually independent, and the evaluation excludes ankle and foot joints. We developed a new quantitative and comprehensive assessment of the activity of rheumatoid arthritis (RA), called the handy rheumatoid activity score, with 38 joints (HRAS38), to overcome these disadvantages of DAS28. Forty-six RA patients who recently completed a 1-year infliximab therapy were evaluated for DAS28 (C-reactive protein; CRP) and HRAS38 at 0, 2, 6, 14, 22, 30, 38, 46, and 54 weeks. The 38-joint evaluation in HRAS38 includes 28 joints of DAS28 except for the shoulder joints, with the addition of ankle and metatarsophalangeal joints. The extent of joint swelling was rated on a scale of 0-3. The HRAS38 score is the cumulative sum of three parameters including: (1) a global assessment of disease activity [visual analog scale (VAS) 0-100 mm] by the patient, (2) swollen joint score based on a 38-joint assessment by a physician (0-114), and (3) serum concentration of CRP (mg/l). Scatter plots of HRAS38 and DAS28(CRP), and subsequent linear regression analysis demonstrated a statistically significant correlation between methodologies (r = 0.846, P < 0.0001). Infliximab treatment resulted in a statistically significant (P < 0.001) decrease in the mean HRAS38 score from 130.5 to 56.5 within 2 weeks of treatment and at 52 weeks of therapy scores were still reduced at 52.5. The mean DAS28(CRP) was also significantly (P < 0.001) reduced from a baseline value of 5.8 to 3.7 after 2 weeks treatment with a final value of 3.2 after 52 weeks of therapy. Infliximab reduced the progression of joint destruction by 85%, for terms before infliximab as determined by radiographic analyses. The degree of progression appeared to be associated with the mean HRAS38, although this observation was not shown to be statistically significant by regression analysis (r = 0.307). The HRAS38 score comprises minimal and independently acquired parameters and is an effective and comprehensive measure of disease activity in RA patients.

Antibodies, Monoclonal↗
PubMed2002

Support vector regression applied to the determination of the developmental age of a Drosophila embryo from its segmentation gene expression patterns.

MOTIVATION: In this paper we address the problem of the determination of developmental age of an embryo from its segmentation gene expression patterns in Drosophila. RESULTS: By applying support vector regression we have developed a fast method for automated staging of an embryo on the basis of its gene expression pattern. Support vector regression is a statistical method for creating regression functions of arbitrary type from a set of training data. The training set is composed of embryos for which the precise developmental age was determined by measuring the degree of membrane invagination. Testing the quality of regression on the training set showed good prediction accuracy. The optimal regression function was then used for the prediction of the gene expression based age of embryos in which the precise age has not been measured by membrane morphology. Moreover, we show that the same accuracy of prediction can be achieved when the dimensionality of the feature vector was reduced by applying factor analysis. The data reduction allowed us to avoid over-fitting and to increase the efficiency of the algorithm.

Aging↗
PubMed1998

Experimental hypoxemic hypoxia: effects of variation in hematocrit on magnetic resonance T2*-weighted brain images.

T2*-weighted gradient echo magnetic resonance images of rat brain were obtained dynamically during acute hypoxemic hypoxia to investigate the relations between changes in cerebral blood oxygen saturation (deltaYb), blood hematocrit (Hct), and R2* (deltaR2*). Images from hypoxemic rats with normal Hct (42.8%+/-2.33%; n=12) were compared with those from hypoxemic rats with mild (33.4%+/-1.88%; n=8) or moderate (27.14%+/-2.7%; n=10) reduction of Hct. A linear relation between deltaYb and deltaR2* was obtained for all three groups. However, the slopes of the linear regressions were statistically different from one another (P < 0.001), with the slopes of the regression lines increasing inversely with Hct; that is, the slope for normal Hct is less than the slope for mildly reduced Hct, which is less than the slope for moderately reduced Hct. These data suggest that for any given reduction in the oxygen saturation of cerebral blood, the deltaR2* will be of a lesser magnitude when the hemoglobin concentration is reduced; the data are consistent with existing theoretical models of deoxyhemoglobin content-dependent effects in T2*-weighted magnetic resonance imaging.

Animals↗
PubMed1984

Comparison of two screening tests for Streptococcus mutans and evaluation of their suitability for mass screenings and private practice.

Two simple microbiological tests for quantitating salivary Streptococcus mutans levels were compared with each other and evaluated for suitability for mass screenings and private practice. Both tests use mitis salivarius medium with bacitracin (MSB) and are selective for S. mutans. One test estimates colonies grown on agar (MSBA) and the other estimates colonies grown in broth that adhere to glass (MSBB). Both are scored from 1 (lowest) to 5 (highest). Children (293) in grades 5 and 6 in Tallahassee, Florida (nonfluoridated) were tested for S. mutans levels. Scores of children by both tests were significantly similar (chi 2, regression and Kappa statistical analysis). Correlation coefficients (regression) between scores and DMFS increments of the previous 4 yr were 0.35 (MSBA) and 0.26 (MSBB). Both tests were very good in identifying children with low caries increments, but positive scores did not correlate well with high caries increments. Sampling and interpreting took 2 min (MSBA) and 1 min (MSBB). Cost of MSBA/child was $1.15, and MSBB/child $1.25. These tests are economical and suitable for mass screenings to identify low risk populations who do not require preventive treatment.

Bacteriological Techniques↗
PubMed2003

Array rank order regression analysis for the detection of gene copy-number changes in human cancer.

cDNA microarray technology has been applied to the detection of DNA copy-number changes in malignant tumors. Test and control genomic DNA samples are differentially labeled and cohybridized to a spotted cDNA microarray. The ratio of test to control fluorescence intensities for each spot reflects relative gene copy number. The low signal-to-noise ratios of this assay and the variable levels of gene amplification and deletion among tumors hamper the detection of deviations from the diploid complement. We describe a regression-based statistical method to test for altered copy number on each gene and apply the technique to copy-number profiles in 10 thyroid tumors. We show that a novel transformation of fluorescence ratios into array rank order efficiently normalizes the heterogeneity among copy-number profiles and improves the reproducibility of the results. Array rank order regression analysis enhances the detection of consistent changes in gene copy number in solid tumors by cDNA microarray-based comparative genome hybridization.

Fluorescence↗
PubMed2000

The one-sample problem from eradication studies of chronic viral infections.

In studies of chronic viral infections, the objective is to estimate probabilities of developing viral eradication and resistance. Complications arise as the laboratory methods used to assess eradication status result in unusual types of censored observations. This paper proposes nonparametric methods for the one-sample analysis of viral eradication/resistance data. We show that the unconstrained nonparametric maximum likelihood estimator of the subdistributions of eradication and resistance are obtainable in closed form. In small samples, these estimators may be inadmissible; thus, we also present an algorithm for obtaining the constrained MLEs based on an isotonic regression of the unconstrained MLEs. Estimators of several functionals of the eradication and resistance subdistributions are also developed and discussed. The methods are illustrated with results from recent hepatitis C clinical trials.

Biometry↗
PubMed1991

Rao's polynomial growth curve model for unequal-time intervals: a menu-driven GAUSS program.

For lack of alternatives, longitudinal data are often analyzed with cross-sectional statistical methods, for instance, t-tests, ANOVA and ordinary least-squares regression. Appropriate statistical software has been generally unavailable to investigators using serial records to study growth and development or treatment effects. In an earlier paper (Schneiderman and Kowalski, Am. J. Phys. Anthropol., 67 (1985) 323-333.) we described a suitable method, Rao's polynomial growth curve model (Rao, Biometrika, 46 (1959) 49-58), and provided an SAS computer program for the analysis of a single sample of complete longitudinal data. This method included the computation of an average polynomial growth curve, its 95% confidence band, its coefficients and corresponding confidence intervals. The present paper extends this method to accommodate a sample with observations made at unequal time-intervals. Significant improvements in the accessibility, operation and user-friendliness of the program have been made, facilitated by recent advances in microcomputer technology. This stand-alone GAUSS program (no compiler necessary) runs on PC-compatibles and is available at a nominal cost. In this report we provide an overview of the statistical model, the general structure of the program, and give an example in which a developmental variable (human upper incisor angulation) is analyzed. Ease of installation and use, speed of execution and color graphic displays of growth curves and confidence bands, and most importantly, suitability to longitudinal data, make this method/program a potentially valuable tool for those interested in growth, development, and treatment effects in humans and other species. Some areas in which this method will have immediate applications are orthodontics, maxillofacial surgery and pediatrics.

Adolescent↗
PubMed1976

Relationships between clinical competence ratings and examination performance.

Relationships between faculty ratings and performance on components of the National Board of Medical Examiners Certifying Examination for Primary Care Physician's Assistants were investigated. A factor analysis of the clinical competence rating form yielded three discrete factors. Results of tests of simple relationships between each rating factor and examination component indicated that four of the six examination components correlated significantly though modestly with at least one of the rating scale factors. The results of multiple regression analyses indicated complex relationships between each of two examination components and the set of rating factors. One implication is that faculty members are able to make discrete judgments about students on more than one dimension.

Certification↗
PubMed2002

Estimation of genetic networks and functional structures between genes by using Bayesian networks and nonparametric regression.

We propose a new method for constructing genetic network from gene expression data by using Bayesian networks. We use nonparametric regression for capturing nonlinear relationships between genes and derive a new criterion for choosing the network in general situations. In a theoretical sense, our proposed theory and methodology include previous methods based on Bayes approach. We applied the proposed method to the S. cerevisiae cell cycle data and showed the effectiveness of our method by comparing with previous methods.

Bayes Theorem↗
PubMed1988

Sociological explanations of economic growth.

Even if questions of how resources are distributed within and between societies are the main concern, it is necessary to continue to grapple with the issue of the causes of economic growth since economic growth and level of development continue to be among the most important causes of inequality, poverty, unemployment, and the quality of life. This paper's dependent variable is the economic growth rate of 55 less developed countries (LDCs) over 2 time periods. 1970-78 and 1965-84. The causal model consists of control variables--level of development and domestic investment in 1965--and a variety of independent variables drawn from major sociological theories of economic growth published during the last 3 decades. Multiple regression analysis shows that, net of the effects of the 2 control variables, the variables which have the strongest effect on economic growth are: 1) direct foreign investment, which has a negative effect, 2) the proportion of the population in military service, and 3) the primary school enrollment ratio, both of which have positive effects on economic growth. On the other hand, variables drawn from some theories receive no empirical support. The mass media of communications, ethnolinguistic heterogeneity, democracy and human rights, income inequality, and state-centric theory's key variable, state strength, all fail to show any significant impact on economic growth rates when the control variables and the significant independent variables are held constant. The theoretical implications of these findings are discussed.

Africa↗
PubMed1989

The costs of Medicare patients in nursing homes in the United States: multiple output analysis.

The reluctance of nursing homes to admit Medicare beneficiaries is well recognised. A possible explanation is that under the current Medicare reimbursement policy, nursing homes do not have adequate incentives to increase admissions. This paper examines that hypothesis. Using a national sample of nursing homes, Medicare-specific marginal costs were estimated from a flexible form of the cost function. In most cases, Medicare-specific marginal costs were well above Medicare reimbursement rates. From an investigation of economies of scale and economies of scope, it appears that reimbursements may be sufficient only in nursing homes that specialize in Medicare beneficiaries. Unless Medicare reimbursements are brought in line with costs, access of Medicare beneficiaries to the nursing homes will remain limited.

Costs and Cost Analysis↗