30 research outputs found
Homogeneous Markov Processes For Breast Cancer Analysis
Sometimes, the introduction of covariates in stochastic processes is required to study their effect on disease history events. However these types of models increase the complexity of analysis, even for simpler processes, and standard software to analyse stochastic processes is limited. In this paper, a method for fitting homogeneous Markov models with covariates is proposed for analysing breast cancer data. Specific software for this purpose has been implemented
Diagnostic accuracy of the Eurotest for dementia: a naturalistic, multicenter phase II study
Abstract Background Available screening tests for dementia are of limited usefulness because they are influenced by the patient's culture and educational level. The Eurotest, an instrument based on the knowledge and handling of money, was designed to overcome these limitations. The objective of this study was to evaluate the diagnostic accuracy of the Eurotest in identifying dementia in customary clinical practice. Methods A cross-sectional, multi-center, naturalistic phase II study was conducted. The Eurotest was administered to consecutive patients, older than 60 years, in general neurology clinics. The patients' condition was classified as dementia or no dementia according to DSM-IV diagnostic criteria. We calculated sensitivity (Sn), specificity (Sp) and area under the ROC curves (aROC) with 95% confidence intervals. The influence of social and educational factors on scores was evaluated with multiple linear regression analysis, and the influence of these factors on diagnostic accuracy was evaluated with logistic regression. Results Sixteen neurologists recruited a total of 516 participants: 101 with dementia, 380 without dementia, and 35 who were excluded. Of the 481 participants who took the Eurotest, 38.7% were totally or functionally illiterate and 45.5% had received no formal education. Mean time needed to administer the test was 8.2+/-2.0 minutes. The best cut-off point was 20/21, with Sn = 0.91 (0.84–0.96), Sp = 0.82 (0.77–0.85), and aROC = 0.93 (0.91–0.95). Neither the scores on the Eurotest nor its diagnostic accuracy were influenced by social or educational factors. Conclusion This naturalistic and pragmatic study shows that the Eurotest is a rapid, simple and useful screening instrument, which is free from educational influences, and has appropriate internal and external validity.</p
Diagnostic accuracy of the Eurotest for dementia: a naturalistic, multicenter phase II study
Clinical Trial, Phase II; Journal Article; Multicenter Study; Research Support, Non-U.S. Gov't; Validation Studies;BACKGROUND
Available screening tests for dementia are of limited usefulness because they are influenced by the patient's culture and educational level. The Eurotest, an instrument based on the knowledge and handling of money, was designed to overcome these limitations. The objective of this study was to evaluate the diagnostic accuracy of the Eurotest in identifying dementia in customary clinical practice.
METHODS
A cross-sectional, multi-center, naturalistic phase II study was conducted. The Eurotest was administered to consecutive patients, older than 60 years, in general neurology clinics. The patients' condition was classified as dementia or no dementia according to DSM-IV diagnostic criteria. We calculated sensitivity (Sn), specificity (Sp) and area under the ROC curves (aROC) with 95% confidence intervals. The influence of social and educational factors on scores was evaluated with multiple linear regression analysis, and the influence of these factors on diagnostic accuracy was evaluated with logistic regression.
RESULTS
Sixteen neurologists recruited a total of 516 participants: 101 with dementia, 380 without dementia, and 35 who were excluded. Of the 481 participants who took the Eurotest, 38.7% were totally or functionally illiterate and 45.5% had received no formal education. Mean time needed to administer the test was 8.2+/-2.0 minutes. The best cut-off point was 20/21, with Sn = 0.91 (0.84-0.96), Sp = 0.82 (0.77-0.85), and aROC = 0.93 (0.91-0.95). Neither the scores on the Eurotest nor its diagnostic accuracy were influenced by social or educational factors.
CONCLUSION
This naturalistic and pragmatic study shows that the Eurotest is a rapid, simple and useful screening instrument, which is free from educational influences, and has appropriate internal and external validity.The Trans-Eurotest Study was funded by the Andalusian Regional Government (Department of Health grants 103/04 and 125/04) and by a research grant provided by Laboratorios Janssen-Cilag, Madrid, Spain.Ye
Diagnostic accuracy of the Eurotest for dementia: a naturalistic, multicenter phase II study-1
<p><b>Copyright information:</b></p><p>Taken from "Diagnostic accuracy of the Eurotest for dementia: a naturalistic, multicenter phase II study"</p><p>BMC Neurology 2006;6():15-15.</p><p>Published online 10 Apr 2006</p><p>PMCID:PMC1459198.</p><p>Copyright © 2006 Carnero-Pardo et al; licensee BioMed Central Ltd.</p>cy Test (dashed line) in identifying dementi
Syncope and bifascicular block in the absence of structural heart disease.
The treatment of patients with bifascicular block (BFB) and syncope in the absence of structural heart disease (SHD) is not well defined. The objective of our study is to compare pacemaker empirical implantation with the use of electrophysiological studies (EPS). This is a prospective cohort study that included 77 patients with unexplained cardiogenic syncope and BFB without structural heart disease between 1997 and 2012. Two groups: 36 patients received empirical pacemakers (Group A) and 41 underwent EPS (Group B) to guide their treatment. The incidence of syncope recurrence and atrioventricular block was lower in group A. Mortality and complication rates were similar between both groups. Multivariate analysis demonstrated a higher number of events (combined endpoint) in group B. Our study shows that treatment according to EPS does not improve the results of a treatment strategy based on empirical pacemaker
Diagnostic accuracy of the Eurotest for dementia: a naturalistic, multicenter phase II study-0
<p><b>Copyright information:</b></p><p>Taken from "Diagnostic accuracy of the Eurotest for dementia: a naturalistic, multicenter phase II study"</p><p>BMC Neurology 2006;6():15-15.</p><p>Published online 10 Apr 2006</p><p>PMCID:PMC1459198.</p><p>Copyright © 2006 Carnero-Pardo et al; licensee BioMed Central Ltd.</p>osis of dementi
Use of Two-Part Regression Calibration Model to Correct for Measurement Error in Episodically Consumed Foods in a Single-Replicate Study Design : EPIC Case Study
In epidemiologic studies, measurement error in dietary variables often attenuates association between dietary intake and disease occurrence. To adjust for the attenuation caused by error in dietary intake, regression calibration is commonly used. To apply regression calibration, unbiased reference measurements are required. Short-term reference measurements for foods that are not consumed daily contain excess zeroes that pose challenges in the calibration model. We adapted twopart regression calibration model, initially developed for multiple replicates of reference measurements per individual to a single-replicate setting. We showed how to handle excess zero reference measurements by two-step modeling approach, how to explore heteroscedasticity in the consumed amount with variance-mean graph, how to explore nonlinearity with the generalized additive modeling (GAM) and the empirical logit approaches, and how to select covariates in the calibration model. The performance of two-part calibration model was compared with the one-part counterpart. We used vegetable intake and mortality data from European Prospective Investigation on Cancer and Nutrition (EPIC) study. In the EPIC, reference measurements were taken with 24-hour recalls. For each of the three vegetable subgroups assessed separately, correcting for error with an appropriately specified two-part calibration model resulted in about three fold increase in the strength of association with all-cause mortality, as measured by the log hazard ratio. Further found is that the standard way of including covariates in the calibration model can lead to over fitting the two-part calibration model. Moreover, the extent of adjusting for error is influenced by the number and forms of covariates in the calibration model. For episodically consumed foods, we advise researchers to pay special attention to response distribution, nonlinearity, and covariate inclusion in specifying the calibration model
Lifestyle factors and mortality risk in individuals with diabetes mellitus: are the associations different from those in individuals without diabetes?
Aims/hypothesis Thus far, it is unclear whether lifestyle recommendations for people with diabetes should be different from those for the general public. We investigated whether the associations between lifestyle factors and mortality risk differ between individuals with and without diabetes. Methods Within the European Prospective Investigation into Cancer and Nutrition (EPIC), a cohort was formed of 6,384 persons with diabetes and 258,911 EPIC participants without known diabetes. Joint Cox proportional hazard regression models of people with and without diabetes were built for the following lifestyle factors in relation to overall mortality risk: BMI, waist/height ratio, 26 food groups, alcohol consumption, leisure-time physical activity, smoking. Likelihood ratio tests for heterogeneity assessed statistical differences in regression coefficients. Results Multivariable adjusted mortality risk among individuals with diabetes compared with those without was increased, with an HR of 1.62 (95% CI 1.51, 1.75). Intake of fruit, legumes, nuts, seeds, pasta, poultry and vegetable oil was related to a lower mortality risk, and intake of butter and margarine was related to an increased mortality risk. These associations were significantly different in magnitude from those in diabetes-free individuals, but directions were similar. No differences between people with and without diabetes were detected for the other lifestyle factors. Conclusions/interpretation Diabetes status did not substantially influence the associations between lifestyle and mortality risk. People with diabetes may benefit more from a healthy diet, but the directions of association were similar. Thus, our study suggests that lifestyle advice with respect to mortality for patients with diabetes should not differ from recommendations for the general population
An epidemiological model for prediction of endometrial cancer risk in Europe
Endometrial cancer (EC) is the fourth most frequent cancer in women in
Europe, and as its incidence is increasing, prevention strategies gain
further pertinence. Risk prediction models can be a useful tool for
identifying women likely to benefit from targeted prevention measures.
On the basis of data from 201,811 women (mostly aged 30-65 years)
including 855 incident EC cases from eight countries in the European
Prospective Investigation into Cancer and Nutrition cohort, a model to
predict EC was developed. A step-wise model selection process was used
to select confirmed predictive epidemiologic risk factors. Piece-wise
constant hazard rates in 5-year age-intervals were estimated in a
cause-specific competing risks model, five-fold-cross-validation was
applied for internal validation. Risk factors included in the risk
prediction model were body-mass index (BMI), menopausal status, age at
menarche and at menopause, oral contraceptive use, overall and by
different BMI categories and overall duration of use, parity, age at
first full-term pregnancy, duration of menopausal hormone therapy and
smoking status (specific for pre, peri- and post-menopausal women).
These variables improved the discriminating capacity to predict risk
over 5 years from 71 % for a model based on age alone to 77 % (overall
C statistic), and the model was well-calibrated (ratio of expected to
observed cases = 0.99). Our model could be used for the identification
of women at increased risk of EC in Western Europe. To achieve an
EC-risk model with general validity, a large-scale cohort-consortium
approach would be needed to assess and adjust for population variation
Blood Metabolic Signatures of Body Mass Index: A Targeted Metabolomics Study in the EPIC Cohort
Metabolomics is now widely used to characterize metabolic phenotypes
associated with lifestyle risk factors such as obesity. The objective of
the present study was to explore the associations of body mass index
(BMI) with 145 metabolites measured in blood samples in the European
Prospective Investigation into Cancer and Nutrition (EPIC) study.
Metabolites were measured in blood from 392 men from the Oxford (UK)
cohort (EPIC-Oxford) and in 327 control subjects who were part of a
nested case-control study on hepatobiliary carcinomas
(EPIC-Hepatobiliary). Measured metabolites included amino acids,
acylcarnitines, hexoses, biogenic amines, phosphatidylcholines, and
sphingomyelins. Linear regression models controlled for potential
confounders and multiple testing were run to evaluate the associations
of metabolite concentrations with BMI. 40 and 45 individual metabolites
showed significant differences according to BMI variations, in the
EPIC-Oxford and EPIC-Hepatobiliary subcohorts, respectively. Twenty two
individual metabolites (kynurenine, one sphingomyelin, glutamate and 19
phosphatidylcholines) were associated with BMI in both subcohorts. The
present findings provide additional knowledge on blood metabolic
signatures of BMI in European adults, which may help identify mechanisms
mediating the relationship of BMI with obesity-related diseases