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PubMed2006

Cost-effectiveness of duloxetine versus routine treatment for U.S. patients with diabetic peripheral neuropathic pain.

UNLABELLED: The purpose of this study was to compare the cost-effectiveness of duloxetine versus routine treatment in management of diabetic peripheral neuropathic pain (DPNP). Two hundred thirty-three patients with DPNP who completed a 12-week, double-blind, placebo-controlled, randomized, multicenter duloxetine trial were re-randomized into a 52-week, open-label trial of duloxetine 60 mg twice daily versus routine treatment. Routine treatment included pain management therapies. Effectiveness was measured by using the bodily pain domain (BP) of the Medical Outcomes Study Short Form 36 (SF-36). Costs were analyzed from 3 perspectives: third party payer (direct medical costs), employer (direct and indirect medical costs), and societal (patient's out-of-pocket costs and total medical costs). Costs of study medications were not included because of limited data. Bootstrap method was applied to calculate statistical inference of the incremental cost-effectiveness ratio (ICER). Routine treatment most frequently used included gabapentin (56%), venlafaxine (36%), and amitripytline (15%). From employer and societal perspectives, duloxetine was cost-effective (ICER= -342 dollars and -429 dollars, respectively, per unit of SF-36 BP; both P <or= .03) and the dominant therapy compared with routine DPNP treatment (both P < .05). From payer perspective, duloxetine trended toward cost-effectiveness (ICER= -249 dollars per unit of SF-36 BP; P <or= .06). These results, however, reflect the controlled environment of a clinical trial. An analysis of real-world data would be beneficial. PERSPECTIVE: Evaluation of the cost and benefit of new pharmacologic treatments is highly desired by decision makers. From both employer perspective and societal perspective (including patient's out-of-pocket costs), this study demonstrated that duloxetine was more cost-effective than routine treatment in management of DPNP.

Adrenergic Uptake Inhibitors↗
PubMed2004

High-performance liquid chromatographic method for the bioequivalence evaluation of desloratadine fumarate tablets in dogs.

A simple HPLC method was developed for the determination of desloratadine in dog plasma and was used for evaluating the bioequivalence of desloratadine fumarate tablets and desloratadine tablets in dogs. Chromatographic separation was performed on a Hypersil CN column (150 mm x 5.0 mm, 5 microm) using a mixture of methanol, acetonitrile and phosphate buffer (pH 5.5; 0.01 mol/l) (35:35:30, v/v/v) as mobile phase delivered at a flow rate of 0.8 ml/min. The detection was set at 241 nm. The limit of quantitation was 5.0 ng/ml. The calibration range was from 5.0 to 800.0 ng/ml. Inter- and intra-day precision ranged from 1.8 to 3.8% and from 2.2 to 9.0%, respectively. The recovery of desloratadine from dog plasma ranged from 78.8 to 82.0%. The developed method was applied to the bioequivalence studies of desloratadine fumarate tablets (test preparation) and desloratadine tablets (reference preparation) in five dogs. Pharmacokinetic parameters t(max), C(max), AUC(0-t), AUC(0- infinity ), t(1/2) were determined from plasma concentration-time profiles of both preparations. The analysis of variance (ANOVA) did not show any significant difference between the two preparations and 90% confidence intervals fell within the acceptable range for bioequivalence. Based on these statistical inferences it was concluded that the two preparations exhibited comparable pharmacokinetic profiles and that desloratadine fumarate tablets was bioequivalent to desloratadine tablets.

Animals↗
PubMed2006

Gender differences in the Swedish driving-license test.

INTRODUCTION: Male drivers between 18-24 years are involved in many more motor-vehicle accidents than female drivers in Sweden. Is there also a gender difference in test performance in the Swedish driving-license tests? Is it a real difference or do any of the items display differential item functioning (DIF) with respect to gender or educational background? METHOD: Two random samples of test-takers' performance on the Swedish theory driving-license test were examined with descriptive and inference statistics. RESULTS: Female test-takers performed better than male test-takers on the theory test, which is a real difference since no items displayed DIF with respect to gender. There was no gender difference in the practical test. The gender difference in the theory test could not be fully explained by differences in educational background. CONCLUSIONS: Although everyone who passes the driving-license test has fulfilled the goals stated in the curriculum, it is possible that the gender differences in the theory test are consistent over time, and therefore might be one factor that explains why male drivers are over-represented in traffic accidents. IMPACT ON INDUSTRY: Gender differences appear persistent over time. Therefore, by improving male test takers' result on the test may lead to positive effects on the male test takers future driving career.

Accidents, Traffic↗
PubMed2004

Movement preparation in self-initiated versus externally triggered movements: an event-related fMRI-study.

In the present study, we used fMRI to investigate whether event-related preparatory processes of self-initiated and externally triggered movements differ. Twenty subjects were examined with 1000 T2*-weighted images in two consecutive sessions. During the first session subjects performed self-initiated abductions of the right index finger. For the second session subjects were instructed to perform the movements in response to visual cues. Number and timing of movements were matched between conditions. For statistical inference on multisubject level, random effects analyses were performed. Significantly enhanced activity during self-initiated compared to externally triggered movements was found within the left SMA, the left pre- and sensorimotor cortex, the right putamen, the left anterior cingulate gyrus, and the left inferior parietal lobe. The significantly increased activity during self-initiated in comparison to externally triggered movements might represent differential demands of the two conditions on the neuronal motor net during movement preparation, reflecting utilization of precise knowledge when to move in self-initiated movements. Our results emphasize a possible role of the primary motor cortex for movement preparation as observed in electrophysiological studies, but do not support a specific involvement of the dorsolateral prefrontal cortex as suggested by former block design studies.

Adult↗
PubMed2005

Unified SPM-ICA for fMRI analysis.

A widely used tool for functional magnetic resonance imaging (fMRI) data analysis, statistical parametric mapping (SPM), is based on the general linear model (GLM). SPM therefore requires a priori knowledge or specific assumptions about the time courses contributing to signal changes. In contradistinction, independent component analysis (ICA) is a data-driven method based on the assumption that the causes of responses are statistically independent. Here we describe a unified method, which combines ICA, temporal ICA (tICA), and SPM for analyzing fMRI data. tICA was applied to fMRI datasets to disclose independent components, whose number was determined by the Bayesian information criterion (BIC). The resulting components were used to construct the design matrix of a GLM. Parameters were estimated and regionally-specific statistical inferences were made about activations in the usual way. The sensitivity and specificity were evaluated using Monte Carlo simulations. The receiver operating characteristic (ROC) curves indicated that the unified SPM-ICA method had a better performance. Moreover, SPM-ICA was applied to fMRI datasets from twelve normal subjects performing left and right hand movements. The areas identified corresponded to motor (premotor, sensorimotor areas and SMA) areas and were consistently task related. Part of the frontal lobe, parietal cortex, and cingulate gyrus also showed transiently task-related responses. The unified method requires less supervision than the conventional SPM and enables classical inference about the expression of independent components. Our results also suggest that the method has a higher sensitivity than SPM analyses.

Adult↗
PubMed2005

fMRI temporal clustering analysis in patients with frequent interictal epileptiform discharges: comparison with EEG-driven analysis.

Temporal clustering analysis (TCA) is an exploratory data-driven technique that has been proposed for the analysis of resting fMRI to localise epileptiform activity without need for simultaneous EEG. Conventionally, fMRI of epileptic activity has been limited to those patients with subtle clinical events or frequent interictal epileptiform EEG discharges, requiring simultaneous EEG recording, from which a linear model is derived to make valid statistical inferences from the fMRI data. We sought to evaluate TCA by comparing the results with those of EEG correlated fMRI in eight selected cases. Cases were selected with clear epileptogenic localisation or lateralisation on the basis of concordant EEG and structural MRI findings, in addition to concordant activations seen on EEG-derived fMRI analyses. In three, areas of activation were seen with TCA but none corresponding to the electro-clinical localisation or activations obtained with EEG driven analysis. Temporal clusters were closely coincident with times of maximal head motion. We feel this is a serious confound to this approach and recommend that interpretation of TCA that does not address motion and physiological noise be treated with caution. New techniques to localise epileptogenic activity with fMRI alone require validation with an appropriate independent measure. In the investigation of interictal epileptiform activity, this is best done with simultaneous EEG recording.

Cluster Analysis↗
PubMed2003

In vitro marginal fit of three all-ceramic crown systems.

STATEMENT OF PROBLEM: Studies on marginal discrepancies of single restorations using various systems and materials have resulted in statistical inferences that are ambiguous because of small sample sizes and limited numbers of measurements per specimen. PURPOSE: The purpose of this study was to compare the marginal adaptation of single anterior restorations made using different systems. MATERIAL AND METHODS: The in vitro marginal discrepancies of 3 different all-ceramic crown systems (Celay In-Ceram, conventional In-Ceram, and IPS Empress 2 layering technique), and a control group of metal ceramic restorations were evaluated and compared by measuring the gap dimension between the crowns and the prepared tooth at the marginal opening. The crowns were made for 1 extracted maxillary central incisor prepared with a 1-mm shoulder margin and 6-degree tapered walls by milling. Thirty crowns per system were fabricated. Crown measurements were recorded with an optical microscope, with an accuracy of +/-0.1 microm, at 50 points spaced approximately 400 microm along the circumferential margin. The criterion of 120 microm was used as the maximum clinically acceptable marginal gap. Mean gap dimensions and standard deviations were calculated for marginal opening. The data were analyzed with a 1-way analysis of variance (alpha=.05). RESULTS: Mean gap dimensions and standard deviations at the marginal opening for the incisor crowns were 87 +/- 34 microm for control, 83 +/- 33 microm for Celay In-Ceram, 112 +/- 55 microm for conventional In-Ceram, and 46 +/- 16 microm for the IPS Empress 2 layering technique. Significant differences were found among the crown groups (P<.05). Compared with the control group, the IPS Empress 2 group had significantly smaller marginal discrepancies (P<.05), and the conventional In-Ceram group exhibited significantly greater marginal discrepancies (P<.05). There was no significant difference between the Celay In-Ceram and the control group. CONCLUSION: Within the limitations of this study, the marginal discrepancies were all within the clinically acceptable standard set at 120 microm. However, the IPS Empress 2 system showed the smallest and most homogeneous gap dimension, whereas the conventional In-Ceram system presented the largest and more variable gap dimension compared with the metal ceramic (control) restoration.

Aluminum Oxide↗
PubMed2004

Bayesian statistics for parasitologists.

Bayesian statistical methods are increasingly being used in the analysis of parasitological data. Here, the basis of differences between the Bayesian method and the classical or frequentist approach to statistical inference is explained. This is illustrated with practical implications of Bayesian analyses using prevalence estimation of strongyloidiasis and onchocerciasis as two relevant examples. The strongyloidiasis example addresses the problem of parasitological diagnosis in the absence of a gold standard, whereas the onchocerciasis case focuses on the identification of villages warranting priority mass ivermectin treatment. The advantages and challenges faced by users of the Bayesian approach are also discussed and the readers pointed to further directions for a more in-depth exploration of the issues raised. We advocate collaboration between parasitologists and Bayesian statisticians as a fruitful and rewarding venture for advancing applied research in parasite epidemiology and the control of parasitic infections.

Animals↗
PubMed1991

Influence of mobile phase composition on evaluation of lipophilicity by partition chromatography.

The problems of the concentration dependence of retention indices and the applicability of extrapolated values in the evaluation of lipophilicity were studied. The reversed-phase high-performance liquid chromatography of arylalkanoic acids were carried out with experimental data for substituted estra-1,3,5 (10)-trienes, benzodiazepines, dermorphine derivatives and dansylamides selected from the literature for this purpose. Fair linear relationships between slopes of concentration dependences and extrapolated and non-extrapolated values of RM and log k' were found. Equivalence of these indices in the evaluation of lipophilicity can be inferred. Statistically significant dependences of log P (sigma pi) values on concentration slopes make it possible to use them as new parameters of lipophilicity. The goodness of fit of these relationships increases when the values of ET(30), as a measure of the solvatochromic solvent polarity of mobile phases, are used instead of the change in modifier concentration.

Acetates↗
PubMed2001

Modeling cancer detection: tumor size as a source of information on unobservable stages of carcinogenesis.

This paper is concerned with modern approaches to mechanistic modeling of the process of cancer detection. Measurements of tumor size at diagnosis represent a valuable source of information to enrich statistical inference on the processes underlying tumor latency. One possible way of utilizing this information is to model cancer detection as a quantal response variable. In doing so, one relates the chance of detecting a tumor to its current size. We present various theoretical results emerging from this approach and illustrate their usefulness with numerical examples and analyses of epidemiological data. An alternative approach based on a threshold type mechanism of tumor detection is briefly described.

Computer Simulation↗
PubMed1997

Estimating clonal heterogeneity and interexperiment variability with the bifurcating autoregressive model for cell lineage data.

We utilize an extension of the variance-components models for cell lineage data in Huggins and Staudte (R.M. Huggins and R.G. Staudte, Variance components models for dependent cell populations. J. Am. Stat. Assoc. 89:19-29 (1994) to analyze NIH3T3 cells grown in two different media. This modeling approach has the advantage of a simple built-in correlation structure between familial members and allows for estimating experimental effects, rather than treating them as random effects. In addition, this methodology gives robust estimates of model parameters together with standard errors required for statistical inference. The importance of clonal heterogeneity and interexperiment variability in modeling eukaryotic cell cycles was previously pointed out by Kuczek and Axelrod (T. Kuczek and D.E. Axelrod, The importance of clonal heterogeneity and interexperimental variability in modeling the eukaryotic cell cycle. Math. Biosci. 79:87-96 (1986). This analysis confirms significantly positive sister-sister correlation when cells are grown in rich or poor medium and negative mother-daughter correlation when cells are grown in poor medium. However, for cells grown in rich medium, Kuczek and Axelrod's analysis gives negative mother-daughter correlations, whereas this analysis gives significant positive mother-daughter correlations.

3T3 Cells↗
PubMed2005

[Common and specific methodological features of checklists].

As medical aims, diagnosis, prognosis, intervention and prevention benefit from scientific method, although they have specific characteristics requiring distinct types of design and statistical analysis. The present article aims to provide definitions of the common and differential features of checklists for the main study designs. Distinctions are made between statistical inference and decision, systematic and random error, confirmation and exploration, prediction and intervention, observation and experimentation, and random allocation and random selection. In addition, the main tools available to researchers to control random and systematic errors are described. How all of these elements are contained in the main types of design is discussed. Importantly, checklists are not a measure of the quality of a study but rather represent minimum requirements that aim to improve the quality of scientific reports.

Authorship↗
PubMed1998

Cycloid psychoses predominate in severe postpartum psychiatric disorders.

BACKGROUND: The nosological status of postpartum psychoses has remained controversial because of their often 'atypical' symptomatology. A polydiagnostic approach may further clarify this issue. METHODS: In a retrospective study, we applied the ICD-10 and Leonhard's classification to 39 patients with severe postpartum psychiatric disorders. The patients were personally reexamined on average 12.5 years (6-26 years) after the onset of the illness. RESULTS: An acute onset and a polymorphous psychotic symptomatology with rapid changes characterized the majority of our cases. Unipolar depressive disorders (28%) and acute polymorphous psychotic disorders (21%) represented the largest proportions within the ICD-10-classification. Applying Leonhard's classification, over half the patients (54%) suffered from a cycloid psychosis. Among cycloid psychoses, motility psychoses clearly predominated. Schizophrenias occurred rarely (10%) according to both classifications. LIMITATIONS: Due to the unknown prevalence of the various diagnoses among women of child-bearing age, it is impossible to statistically infer a specific association between childbirth and a distinct diagnosis from our data. CONCLUSIONS: Our findings suggest that cycloid psychoses, in particular motility psychoses, account for the majority of postpartum psychoses, and do not support the hypothesis of a nosological independence of postpartum psychoses.

Adult↗
PubMed2001

Sample size and power calculations with correlated binary data.

Correlated binary data are common in biomedical studies. Such data can be analyzed using Liang and Zeger's generalized estimating equations (GEE) approach. An attractive point of the GEE approach is that one can use a misspecified working correlation matrix, such as the working independence model (i.e., the identity matrix), and draw (asymptotically) valid statistical inference by using the so-called robust or sandwich variance estimator. In this article we derive some explicit formulas for sample size and power calculations under various common situations. The given formulas are based on using the robust variance estimator in GEE. We believe that these formulas will facilitate the practice in planning two-arm clinical trials with correlated binary outcome data.

Clinical Trials as Topic↗
PubMed2000

Clues and uncertainties in the risk assessment of arsenic in drinking water.

On the basis of studies of the prevalence of skin cancer among users of As-rich well water in Taiwan, WHO experts recommended in 1984 a maximum As concentration of 50 microg/litre in drinking water. Since that time, a plethora of non-cancer as well as cancer effects has been observed in several other populations sustaining a chronic exposure to various As concentrations in drinking water. This prompted a revision of the standard and a provisional guideline of 10 microg/litre was recommended in 1993. While the uncertainty linked to the statistical inferences leading to the guideline are reduced by the fact that they are directly estimated from human data and result from extrapolations made relatively close to observed exposure levels, developed guideline depends strongly on the choice of the dose-response model (linear, quadratic, hockey-stick) and the accuracy of the exposure data. The potential exposure to As sources other than drinking water, dietary habits and genetic characteristics of the populations may also make more difficult the inference of a recommendation for As concentration in drinking water. Owing to the huge cost of strongly reducing the current As in water standard, many efforts are presently made to clarify the quantitative aspects of As-induced cancers, particularly at low dose levels. New data on the metabolism and carcinogenic mechanism of As in humans along with the results of epidemiological studies presently under way in several countries will help to reduce the uncertainty in the risk assessment of As.

Arsenic↗
PubMed1999

Dose confirmation of moxidectin pour-on against natural nematode infections in lactating dairy cows.

The nematocidal effectiveness of moxidectin, administered topically at the rate of 500 mcg/kg BW, was determined for lactating dairy cows. Naturally infected animals were given either topical vehicle or moxidectin (Cydectin Pour-On Fort Dodge Animal Health) at the rate of 1 ml/10 kg BW (10 animals per treatment group), and sacrificed 14-18 days post-treatment for nematode enumeration. 100% efficacies were recorded for Ostertagia lyrata males, Cooperia punctata males and Oesophagostomum radiatum L4, with treatment group differences in geometric means significant (P < 0.05) for all. Populations of Trichostrongylus L4 and adult O. radiatum were also reduced by 100%, but low prevalence rates in the control animals precluded meaningful statistical inference. Nematode populations for which efficacies ranged from 96.7 to 99.6% (based on geometric means) and for which treatment group differences were significant (P < 0.05) included Ostertagia spp. adult females, inhibited L4 and developing L4, O. ostertagi adult males, Trichostrongylus axei adults and Cooperia spp. adult females. For all nematodes combined, moxidectin was 98.9% efficacious. In addition to exhibiting excellent nematocidal effectiveness, topical moxidectin was demonstrated to be safe, with animal health and milk production unaffected during the study.

Abomasum↗
PubMed1982

Ontogenic development of EEG-asymmetry in early infantile autism.

Autoregressive (AR) analysis and component analysis were done on EEGs during sleep stage 2 in normal and autistic children, since AR-coefficients of EEG characterize the autocovariance and power spectral density of EEG. In addition, as the generalized distance of the average AR-coefficient vector of an EEG group at one side from that at the opposite side exhibits an F-distribution, the statistical inferences were determined, as to whether there is hemispheric specialization in EEG in 21 right-handed autistic children and whether there is a difference between the AR-spectral pattern of EEG in the autistic children and that of 28 normal children of the same age range. The results obtained are as follows: 1. Significant hemispheric lateralization in EEG at the significant level of 0.01 was observed in normal children, whereas no lateralization was confirmed in autistic children. 2. Random click stimulation had cumulative effects on the hemispheric lateralization in the normal children, but not in the autistic children. On the contrary, the effects of random flash light stimulation on hemispheric asymmetry were verified in the autistic children as well as in the normal children. 3. The EEG components of autistic children were significantly different from the normal ones in the frequency range of alpha-2 component waves at bilateral frontal (Fp1 and Fp2) regions and the activity of these component waves was higher in the autistic children than in the normal ones over 5 years old. 4. These findings suggest that autistic children are not only less responsive to external stimuli, but also neurophysiologically less active in the internal regulatory mechanism.

Acoustic Stimulation↗
PubMed2001

Reproducibility of optical biometry using partial coherence interferometry : intraobserver and interobserver reliability.

PURPOSE: To evaluate the intraobserver and interobserver variability in axial length (AL), anterior chamber depth (ACD), and corneal radius measurements using an optical biometry instrument based on partial coherence interferometry (PCI). SETTING: Johannes Gutenberg University, Mainz, Germany. METHODS: In this observational case series and interobserver reliability trial, 30 healthy, emmetropic to moderately myopic eyes of 15 volunteers were evaluated. The AL, ACD, and corneal radius were measured 20 times in 10 eyes by 1 observer to evaluate the intraobserver variability. To evaluate the interobserver variability, the measurements were taken in 20 eyes by 5 different observers. Measurements were performed using the IOLMaster (Carl Zeiss) based on PCI. The data description is based on coefficients of variation and the statistical inference on reliability estimation based on analysis of variance. The main outcome measures were intraobserver and interobserver variability and reliability in AL, ACD, and corneal radii. RESULTS: The intraobserver variability (SD) was +/-25.6 microm for AL, +/-33.4 microm for ACD, and +/-12.9 microm for corneal radius. The coefficients of variation were 0.1%, 0.9%, and 0.17%, respectively. The interobserver variability (SD) was +/-21.5 microm for AL, +/-29.8 microm for ACD, and +/-15.9 microm for corneal radius. The coefficients of variation were 0.09%, 0.82%, and 0.21%, respectively. The reliability was 99.9% for AL, 97.8% for ACD, and 99.8%/99.5% for corneal radius (r1/r2). The slightly reduced reliability in ACD measurement was caused by a reduced intraobserver reliability of 1 of the 5 observers (R = 0.87). CONCLUSION: Partial coherence biometry using the IOLMaster for AL measurement was highly reliable, offering observer-independent measurement results.

Adult↗