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Multiple Variables (multiple + variable)
Selected AbstractsValproate-induced thrombocytopenia: a prospective monotherapy studyEPILEPSIA, Issue 3 2008Wassim Nasreddine Summary Purpose: The frequency of valproate (VPA)-induced thrombocytopenia varied widely in previous studies, due to methodological differences. Our objective was to evaluate the relationship between trough VPA plasma levels and platelet counts and assess risk factors for the development of thrombocytopenia. Methods: Patients with refractory partial epilepsy were enrolled in this double-blind, multicenter, concentration,response trial that evaluated the efficacy and safety of high versus low trough plasma VPA concentrations following administration of divalproex sodium as monotherapy. Trough VPA concentrations and concomitant platelet counts were drawn at baseline and intermittently throughout the 24-week trial. Bivariate correlations and multivariate stepwise regression analysis were performed between platelet counts and multiple variables. A logistic regression analysis was done to determine the probability of developing thrombocytopenia at various VPA levels. Results: A total of 851 VPA levels and concomitant platelet counts were analyzed in 265 patients. Of these, 17.7% of patients experienced at least one episode of thrombocytopenia (platelet count , 100,000/,l) after exposure to divalproex sodium. A significant negative correlation was found between VPA levels and platelet counts. Women were significantly more likely to develop thrombocytopenia. The probability of developing thrombocytopenia substantially increased at trough VPA levels above 100 ,g/ml in women and above 130 ,g/ml in men. Discussion: Our data strongly support a causal relationship between rising plasma VPA levels and reduced platelet counts, with additional risk factors including female gender and lower baseline platelet counts. [source] Linking climate change modelling to impacts studies: recent advances in downscaling techniques for hydrological modellingINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2007H. J. Fowler Abstract There is now a large published literature on the strengths and weaknesses of downscaling methods for different climatic variables, in different regions and seasons. However, little attention is given to the choice of downscaling method when examining the impacts of climate change on hydrological systems. This review paper assesses the current downscaling literature, examining new developments in the downscaling field specifically for hydrological impacts. Sections focus on the downscaling concept; new methods; comparative methodological studies; the modelling of extremes; and the application to hydrological impacts. Consideration is then given to new developments in climate scenario construction which may offer the most potential for advancement within the ,downscaling for hydrological impacts' community, such as probabilistic modelling, pattern scaling and downscaling of multiple variables and suggests ways that they can be merged with downscaling techniques in a probabilistic climate change scenario framework to assess the uncertainties associated with future projections. Within hydrological impact studies there is still little consideration given to applied research; how the results can be best used to enable stakeholders and managers to make informed, robust decisions on adaptation and mitigation strategies in the face of many uncertainties about the future. It is suggested that there is a need for a move away from comparison studies into the provision of decision-making tools for planning and management that are robust to future uncertainties; with examination and understanding of uncertainties within the modelling system. Copyright © 2007 Royal Meteorological Society [source] Stage 2 Pressure Ulcer Healing in Nursing HomesJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2008Nancy Bergstrom PhD OBJECTIVES: To identify resident and wound characteristics associated with Stage 2 pressure ulcer (PrU) healing time in nursing home residents. DESIGN: Retrospective cohort study with convenience sampling. SETTING: One hundred two nursing homes participating in the National Pressure Ulcer Long-Term Care Study (NPULS) in the United States. PARTICIPANTS: Seven hundred seventy-four residents aged 21 and older with length of stay of 14 days or longer who had at least one initial Stage 2 (hereafter Stage 2) PrU. MEASUREMENTS: Data collected for each resident over a 12-week period included resident characteristics and PrU characteristics, including area when first reached Stage 2. Data were obtained from medical records and logbooks. RESULTS: There were 1,241 initial Stage 2 PrUs on 774 residents; 563 (45.4%) healed. Median time to heal was 46 days. Initial area was significantly associated with days to heal. Using Kaplan-Meier survival analyses, median days to heal was 33 for small (,1 cm2), 53 days for medium (>1 to ,4 cm2), and 73 days for large (>4 cm2) ulcers. Using Cox proportional hazard regression models to examine effects of multiple variables simultaneously, small and medium ulcers and ulcers on residents with agitation and those who had oral eating problem healed more quickly, whereas ulcers on residents who required extensive assistance with seven to eight activities of daily living (ADLs), who temporarily left the facility for the emergency department (ED) or hospital, or whose PrU was on an extremity healed more slowly. CONCLUSION: PrUs on residents with agitation or with oral eating problems were associated with faster healing time. PrUs located on extremities, on residents who went temporarily to the ED or hospital, and on residents with high ADL disabilities were associated with slower healing time. Interaction between PrU size and place of onset was also associated with healing time. For PrU onset before or after admission to the facility, smaller size was associated with faster healing time. [source] The Likelihood as Statistical Evidence in Multiple Comparisons in Clinical Trials: No Free LunchBIOMETRICAL JOURNAL, Issue 3 2006Edward L. Korn Abstract The likelihood ratio summarizes the strength of statistical evidence for one simple pre-determined hypothesis versus another. However, it does not directly address the multiple comparisons problem. In this paper we discuss some concerns related to the application of likelihood ratio methods to several multiple comparisons issues in clinical trials, in particular, subgroup analysis, multiple variables, interim monitoring, and data driven choice of hypotheses. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Calibration of Multivariate Scatter plots for Exploratory Analysis of Relations Within and Between Sets of Variables in Genomic ResearchBIOMETRICAL JOURNAL, Issue 6 2005Jan Graffelman Abstract The scatter plot is a well known and easily applicable graphical tool to explore relationships between two quantitative variables. For the exploration of relations between multiple variables, generalisations of the scatter plot are useful. We present an overview of multivariate scatter plots focussing on the following situations. Firstly, we look at a scatter plot for portraying relations between quantitative variables within one data matrix. Secondly, we discuss a similar plot for the case of qualitative variables. Thirdly, we describe scatter plots for the relationships between two sets of variables where we focus on correlations. Finally, we treat plots of the relationships between multiple response and predictor variables, focussing on the matrix of regression coefficients. We will present both known and new results, where an important original contribution concerns a procedure for the inclusion of scales for the variables in multivariate scatter plots. We provide software for drawing such scales. We illustrate the construction and interpretation of the plots by means of examples on data collected in a genomic research program on taste in tomato. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Decreased drug-cue-induced attentional bias in individuals with treated and untreated drug dependenceACTA NEUROPSYCHIATRICA, Issue 4 2009Simona Gardini Objective: The present study investigated the attentional bias induced by drug-related stimuli in active abusers; abstinent abusers on opioid substitution therapy; and abstinent drug-dependent patients in recovery on a community-based non-pharmacological therapy programme. Drug-dependent groups included both cocaine and heroin abusers. Methods: Classical and emotional Stroop tasks were used to test all drug-dependent patients and controls with no history of addiction. Response times were recorded. An interference effect was obtained by comparing the congruent and incongruent conditions in the classical Stroop version. An attentional bias towards drug cues was derived by comparing latencies in the neutral and emotional conditions of the emotional Stroop. Results: No between-group differences were found in the classical Stroop. In the emotional Stroop, active drug-dependent patients showed higher attentional bias (i.e. longer response times to drug-related words) than any of the other three groups. Conclusion: The attentional bias induced by drug cues in patients with addiction disorder might change depending on the patients' clinical status. All treated patients, whether on opioid substitution therapy or on community therapy, showed less attentional bias towards drug-related stimuli than active drug users, although the observed smaller bias was most likely induced by therapy acting through different mechanisms. Although drug-cues response is influenced by other multiple variables, e.g. motivation, craving, classical conditioning and substance availability, these data lend support to the hypothesis that treatment might contribute to decrease the attentional bias towards drug cues, which seems to play a critical role in achieving a positive outcome in the treatment of addiction. [source] Association between commensal bacteria and opportunistic pathogens in the dental plaque of elderly individualsCLINICAL MICROBIOLOGY AND INFECTION, Issue 8 2006A. Tada Abstract Opportunistic infections in the oral cavity of the elderly may increase the incidence of systemic disease. The objective of this study was to investigate the differences in the oral bacterial flora between dependent elderly (inpatients) and independent elderly (community-dwelling residents). After multiple variables were taken into account, inpatients had significantly lower detection rates than community-dwelling residents for ,-streptococci (p < 0.001) and Neisseria (p 0.004), and higher detection rates for Pseudomonas aeruginosa (p 0.024), methicillin-resistant Staphylococcus aureus (MRSA) (p 0.011) and Actinomyces spp. (p 0.005). Among inpatients, the requirement for a high degree of care was related negatively to detection of ,-streptococci, but was related significantly to detection of P. aeruginosa (p 0.018) or MRSA (p 0.004). Tube-fed inpatients had a significantly lower detection rate for ,-streptococci (p 0.041) and a higher detection rate for P. aeruginosa (p 0.004) than those who did not require tube feeding. Inpatients with a history of antibiotic use had a significantly lower detection rate for ,-streptococci (p 0.049) and a higher detection rate for MRSA (p 0.007) than those without a history of antibiotic use. The detection rates for P. aeruginosa or MRSA in inpatients without ,-streptococci were higher than in inpatients with ,-streptococci after controlling for age and gender (P. aeruginosa, p 0.006; MRSA, p 0.001). Overall, detection of ,-streptococci had an inverse correlation with the detection of P. aeruginosa and MRSA in the oral cavity and is likely to be an indicator of pathogenic bacterial infection. [source] A Multidimensional Meta-Analysis of Psychotherapy for Bulimia NervosaCLINICAL PSYCHOLOGY: SCIENCE AND PRACTICE, Issue 3 2003Heather Thompson-Brenner We report a multidimensional meta-analysis of psychotherapy trials for bulimia nervosa published between 1980 and 2000, including multiple variables in addition to effect size such as inclusion and exclusion, recovery, and sustained recovery rates. The data point to four conclusions. First, psychotherapy leads to large improvements from baseline. Approximately 40% of patients who complete treatment recover completely, although 60% maintain clinically significant posttreatment symptoms. Second, individual therapy shows substantially better effects than group therapy for the therapies tested. Third, additional approaches or treatment parameters (e.g., number of sessions) need to be tested for the substantial number of patients who enter treatment and do not recover. Finally, the utility of meta-analyses can be augmented by including a wider range of outcome metrics, such as recovery rates and posttreatment symptom levels. [source] | ||||||||||