The impact of fasting on the interpretation of triglyceride levels for predicting myocardial infarction risk in HIV-positive individuals: the D:A:D study.

We assessed whether fasting modifies the prognostic value of these measurements for the risk of myocardial infarction (MI). Analyses used mixed effect models and Poisson regression. After confounders were controlled for, fasting triglyceride levels were, on average, 0.122 mmol/L lower than nonfasting levels. Each 2-fold increase in the latest triglyceride level was associated with a 38% increase in MI risk (relative rate, 1.38; 95% confidence interval, 1.26-1.51); fasting status did not modify this association. Our results suggest that it may not be necessary to restrict analyses to fasting measurements when considering MI risk.

Apports de la médecine nucléaire en cardiologie préventive: l'exemple du syndrome métabolique [Value of nuclear medicine in preventive cardiology: the metabolic syndrome example]

Metabolic syndrome represents a grouping of risk factors closely linked to cardiovascular diseases and diabetes. At first, nuclear medicine has no direct application in cardiology at the level of primary prevention, but positron emission tomography is a non invasive imaging technique that can assess myocardial perfusion as well as the endothelium-dependent coronary vasomotion--a surrogate marker of cardiovascular event rate--thus finding an application in studying coronary physiopathology. As the prevalence of the metabolic syndrome is still unknown in Switzerland, we will estimate it from data available in the frame of a health promotion program. Based on the deleterious effect on the endothelium already observed with two components, we will estimate the number of persons at risk in Switzerland.

Using register data to assess the impact of response enhancement methods on the risk of nonresponse bias and survey costs

The pursuit of high response rates to minimise the threat of nonresponse bias continues to dominate decisions about resource allocation in survey research. Yet a growing body of research has begun to question this practice. In this study, we use previously unavailable data from a new sampling frame based on population registers to assess the value of different methods designed to increase response rates on the European Social Survey in Switzerland. Using sampling data provides information about both respondents and nonrespondents, making it possible to examine how changes in response rates resulting from the use of different fieldwork methods relate to changes in the composition and representativeness of the responding sample. We compute an R-indicator to assess representativity with respect to the sampling register variables, and find little improvement in the sample composition as response rates increase. We then examine the impact of response rate increases on the risk of nonresponse bias based on Maximal Absolute Bias (MAB), and coefficients of variation between subgroup response rates, alongside the associated costs of different types of fieldwork effort. The results show that increases in response rate help to reduce MAB, while only small but important improvements to sample representativity are gained by varying the type of effort. These findings lend further support to research that has called into question the value of extensive investment in procedures aimed at reaching response rate targets and the need for more tailored fieldwork strategies aimed both at reducing survey costs and minimising the risk of bias.

P value and the theory of hypothesis testing: an explanation for new researchers.

In the 1920s, Ronald Fisher developed the theory behind the p value and Jerzy Neyman and Egon Pearson developed the theory of hypothesis testing. These distinct theories have provided researchers important quantitative tools to confirm or refute their hypotheses. The p value is the probability to obtain an effect equal to or more extreme than the one observed presuming the null hypothesis of no effect is true; it gives researchers a measure of the strength of evidence against the null hypothesis. As commonly used, investigators will select a threshold p value below which they will reject the null hypothesis. The theory of hypothesis testing allows researchers to reject a null hypothesis in favor of an alternative hypothesis of some effect. As commonly used, investigators choose Type I error (rejecting the null hypothesis when it is true) and Type II error (accepting the null hypothesis when it is false) levels and determine some critical region. If the test statistic falls into that critical region, the null hypothesis is rejected in favor of the alternative hypothesis. Despite similarities between the two, the p value and the theory of hypothesis testing are different theories that often are misunderstood and confused, leading researchers to improper conclusions. Perhaps the most common misconception is to consider the p value as the probability that the null hypothesis is true rather than the probability of obtaining the difference observed, or one that is more extreme, considering the null is true. Another concern is the risk that an important proportion of statistically significant results are falsely significant. Researchers should have a minimum understanding of these two theories so that they are better able to plan, conduct, interpret, and report scientific experiments.

The role of a Mediterranean diet on the risk of oral and pharyngeal cancer.

BACKGROUND: The Mediterranean diet has a beneficial role on various neoplasms, but data are scanty on oral cavity and pharyngeal (OCP) cancer. METHODS: We analysed data from a case-control study carried out between 1997 and 2009 in Italy and Switzerland, including 768 incident, histologically confirmed OCP cancer cases and 2078 hospital controls. Adherence to the Mediterranean diet was measured using the Mediterranean Diet Score (MDS) based on the major characteristics of the Mediterranean diet, and two other scores, the Mediterranean Dietary Pattern Adherence Index (MDP) and the Mediterranean Adequacy Index (MAI). RESULTS: We estimated the odds ratios (ORs), and the corresponding 95% confidence intervals (CI), for increasing levels of the scores (i.e., increasing adherence) using multiple logistic regression models. We found a reduced risk of OCP cancer for increasing levels of the MDS, the ORs for subjects with six or more MDS components compared with two or less being 0.20 (95% CI 0.14-0.28, P-value for trend <0.0001). The ORs for the highest vs the lowest quintile were 0.20 (95% CI 0.14-0.28) for the MDP score (score 66.2 or more vs less than 57.9), and 0.48 (95% CI 0.33-0.69) for the MAI score (score value 2.1 or more vs value less 0.92), with significant trends of decreasing risk for both scores. The favourable effect of the Mediterranean diet was apparently stronger in younger subjects, in those with a higher level of education, and in ex-smokers, although it was observed in other strata as well. CONCLUSIONS: Our study provides strong evidence of a beneficial role of the Mediterranean diet on OCP cancer.

Are patients at nutritional risk more prone to complications after major urological surgery?

PURPOSE: The nutritional risk score is a recommended screening tool for malnutrition. While a nutritional risk score of 3 or greater predicts adverse outcomes after digestive surgery, to our knowledge its predictive value for morbidity after urological interventions is unknown. We determined whether urological patients at nutritional risk are at higher risk for complications after major surgery than patients not at nutritional risk. MATERIALS AND METHODS: We performed a prospective observational study in consecutive patients undergoing major surgery. A priori sample calculation resulted in a study cohort of 220 patients. Interim analysis was planned after 110 patients. The nutritional risk score was assessed preoperatively by a specialized study nurse. Nutritional care was standardized in all patients. Postoperative complications were defined previously using the standardized Dindo-Clavien classification. The primary end point was 30-day morbidity. Univariate and multivariate analysis was performed to identify predictors of complications. RESULTS: The study was discontinued due to significant results after interim analysis. A total of 125 patients were included in analysis from June 2011 to June 2012 and 15 were excluded because of incomplete data. Of 51 patients at nutritional risk 38 (74%) presented with at least 1 complication compared to 28 of 59 controls (47%). Patients at nutritional risk were at threefold risk for complications on univariate and multivariate analysis (OR 3.3, 95% CI 1.3-8.0). Cystectomy was the only other predictor of morbidity (OR 10, 95% CI 2-48). CONCLUSIONS: Patients at nutritional risk are more prone to complications after major urological procedures. Whether this increased morbidity can be reversed by perioperative nutritional support should be studied.

Optimal dividend strategies for a compound Poisson risk process under transaction costs and power utility

We characterize the value function of maximizing the total discounted utility of dividend payments for a compound Poisson insurance risk model when strictly positive transaction costs are included, leading to an impulse control problem. We illustrate that well known simple strategies can be optimal in the case of exponential claim amounts. Finally we develop a numerical procedure to deal with general claim amount distributions.

Improvement of cardiovascular risk prediction: time to review current knowledge, debates, and fundamentals on how to assess test characteristics.

Cardiovascular risk assessment might be improved with the addition of emerging, new tests derived from atherosclerosis imaging, laboratory tests or functional tests. This article reviews relative risk, odds ratios, receiver-operating curves, posttest risk calculations based on likelihood ratios, the net reclassification improvement and integrated discrimination. This serves to determine whether a new test has an added clinical value on top of conventional risk testing and how this can be verified statistically. Two clinically meaningful examples serve to illustrate novel approaches. This work serves as a review and basic work for the development of new guidelines on cardiovascular risk prediction, taking into account emerging tests, to be proposed by members of the 'Taskforce on Vascular Risk Prediction' under the auspices of the Working Group 'Swiss Atherosclerosis' of the Swiss Society of Cardiology in the future.

Incidence, complications and risk factors for severe falls in patients on maintenance haemodialysis.

BACKGROUND: Falls have been insufficiently studied in patients on maintenance haemodialysis (MHD). This study assessed the incidence and complications of severe falls and the ability of risk factors, including the Performance-Oriented Mobility Assessment (POMA) test, to predict them in this population. METHODS: All patients on MHD from our centre were asked to participate in this survey. POMA test and a record of risk factors for falls were obtained at baseline. Severe falls, as defined by an admission in an emergency ward, were documented prospectively. RESULTS: Eighty-four patients (median age 69.5 years, minimum 26 years, maximum 85 years) were enrolled. Predialytic POMA scores were low (median 20, minimum 5, maximum 26). After a mean follow-up of 20.6 months (142.2 patient-years), 31 severe falls were recorded in 24 patients (28.6%; incidence 0.22 per patient-year) and complicated by fractures in 54.8% of severe falls. In univariate analysis, age, a past history of falls, malnutrition, depression, but not POMA score, were associated with severe falls. A POMA score of >21 had a negative predictive value of 82%. CONCLUSIONS: Severe falls were common in MHD patients in this study and resulted in fractures in >50% of the cases. They were associated with ageing, a past history of falls, malnutrition and depression. Although there was a trend towards a lower POMA score in fallers as compared to non-fallers, the POMA score was not an independent predictor of severe falls in this study. These data may help to stratify the patient's risk of falling in order to target programmes to prevent falls in this population.

Predictive value of readiness, importance, and confidence in ability to change drinking and smoking.

BACKGROUND: Visual analog scales (VAS) are sometimes used to assess change constructs that are often considered critical for change. Aims of Study: 1.) To determine the association of readiness to change, importance of changing and confidence in ability to change alcohol and tobacco use at baseline with the risk for drinking (more than 21 drinks per week/6 drinks or more on a single occasion more than once per month) and smoking (one or more cigarettes per day) six months later. 2.) To determine the association of readiness, importance and confidence with alcohol (number of drinks/week, number of binge drinking episodes/month) and tobacco (number of cigarettes/day) use at six months. METHODS: This is a secondary analysis of data from a multi-substance brief intervention randomized trial. A sample of 461 Swiss young men was analyzed as a prospective cohort. Participants were assessed at baseline and six months later on alcohol and tobacco use, and at baseline on readiness to change, importance of changing and confidence in ability to change constructs, using visual analog scales ranging from 1-10 for drinking and smoking behaviors. Regression models controlling for receipt of brief intervention were employed for each change construct. The lowest level (1-4) of each scale was the reference group that was compared to the medium (5-7) and high (8-10) levels. RESULTS: Among the 377 subjects reporting unhealthy alcohol use at baseline, mean (SD) readiness, importance and confidence to change drinking scores were 3.9 (3.0), 2.7 (2.2) and 7.2 (3.0), respectively. At follow-up, 108 (29%) reported no unhealthy alcohol use. Readiness was not associated with being risk-free at follow-up, but high importance (OR 2.94; 1.15, 7.50) and high confidence (OR 2.88; 1.46, 5.68) were. Among the 255 smokers at baseline, mean readiness, importance and confidence to change smoking scores were 4.6 (2.6), 5.3 (2.6) and 5.9 (2.7), respectively. At follow-up, 13% (33) reported no longer smoking. Neither readiness nor importance was associated with being a non-smoker, whereas high confidence (OR 3.29; 1.12, 9.62) was. CONCLUSIONS: High confidence in ability to change was associated with favorable outcomes for both drinking and smoking, whereas high importance was associated only with a favorable drinking outcome. This study points to the value of confidence as an important predictor of successful change for both drinking and smoking, and shows the value of importance in predicting successful changes in alcohol use. TRIAL REGISTRATION NUMBER: ISRCTN78822107.

Expérience de dix ans de réanimation chirurgicale d'un centre hospitalier universitaire. Détermination d'un critère d'identification des patients à risque de décéder de coagulopathie irréversible [10 years experience in surgical resuscitation at a university hospital center. Determination of a criterion for identifying patients at risk for fatal irreversible coagulopathy]

The authors evaluated ten years of surgical reanimation in the University Centre of Lausanne (CHUV). Irreversible coagulopathy (IC) is the predominant cause of death for the polytraumatized patient. Acidosis, hypothermy, and coagulation troubles are crucial elements of this coagulopathy. The authors looked for a criterion allowing the identification of dying of IC. In a retrospective study, laboratory results of pH, TP, PTT, thrombocyte count and the need for blood transfusion units were checked for each major step of the primary evaluation and treatment of the polytraumatized patients. These results were considered as critical according to criteria of the literature (30). The authors conclude that the apparation of a third critical value may be useful to identify the polytraumatized patient at risk of dying of IC status. This criterion may also guide the trauma team in selecting a damage control surgical approach (DCS). This criterion was then introduced into an algorithm involving the Emergency Department, the operating room and the Intensive Care Unit. This criterion is a new tool to address the patient at the crucial moment to the appropriate hospital structure.

Testing extreme value copulas to estimate the quantile

Testing weather or not data belongs could been generated by a family of extreme value copulas is difficult. We generalize a test and we prove that it can be applied whatever the alternative hypothesis. We also study the effect of using different extreme value copulas in the context of risk estimation. To measure the risk we use a quantile. Our results have motivated by a bivariate sample of losses from a real database of auto insurance claims. Methods are implemented in R.

Anemia and chronic kidney disease are potential risk factors for mortality in stroke patients: a historic cohort study.

BACKGROUND: Chronic kidney disease (CKD) is associated to a higher stroke risk. Anemia is a common consequence of CKD, and is also a possible risk factor for cerebrovascular diseases. The purpose of this study was to examine if anemia and CKD are independent risk factors for mortality after stroke. METHODS: This historic cohort study was based on a stroke registry and included patients treated for a first clinical stroke in the stroke unit of one academic hospital over a three-year period. Mortality predictors comprised demographic characteristics, CKD, glomerular filtration rate (GFR), anemia and other stroke risk factors. GFR was estimated by means of the simplified Modification of Diet in Renal Disease formula. Renal function was assessed according to the Kidney Disease Outcomes Quality Initiative (K/DOQI)-CKD classification in five groups. A value of hemoglobin < 120 g/L in women and < 130 g/L in men on admission defined anemia. Kaplan-Meier survival curves and Cox models were used to describe and analyze one-year survival. RESULTS: Among 890 adult stroke patients, the mean (Standard Deviation) calculated GFR was 64.3 (17.8) ml/min/1.73 m2 and 17% had anemia. Eighty-two (10%) patients died during the first year after discharge. Among those, 50 (61%) had K/DOQI CKD stages 3 to 5 and 32 (39%) stages 1 or 2 (p < 0.001). Anemia was associated with an increased risk of death one year after discharge (p < 0.001). After adjustment for other factors, a higher hemoglobin level was independently associated with decreased mortality one year after discharge [hazard ratio (95% CI) 0.98 (0.97-1.00)]. CONCLUSIONS: Both CKD and anemia are frequent among stroke patients and are potential risk factors for decreased one-year survival. The inclusion of patients with a first-ever clinical stroke only and the determination of anemia based on one single measure, on admission, constitute limitations to the external validity. We should investigate if an early detection and management of both CKD and anemia could improve survival in stroke patients.

Developing psychosis and its risk States through the lens of schizotypy.

Starting from the early descriptions of Kraepelin and Bleuler, the construct of schizotypy was developed from observations of aberrations in nonpsychotic family members of schizophrenia patients. In contemporary diagnostic manuals, the positive symptoms of schizotypal personality disorder were included in the ultra high-risk (UHR) criteria 20 years ago, and nowadays are broadly employed in clinical early detection of psychosis. The schizotypy construct, now dissociated from strict familial risk, also informed research on the liability to develop any psychotic disorder, and in particular schizophrenia-spectrum disorders, even outside clinical settings. Against the historical background of schizotypy it is surprising that evidence from longitudinal studies linking schizotypy, UHR, and conversion to psychosis has only recently emerged; and it still remains unclear how schizotypy may be positioned in high-risk research. Following a comprehensive literature search, we review 18 prospective studies on 15 samples examining the evidence for a link between trait schizotypy and conversion to psychosis in 4 different types of samples: general population, clinical risk samples according to UHR and/or basic symptom criteria, genetic (familial) risk, and clinical samples at-risk for a nonpsychotic schizophrenia-spectrum diagnosis. These prospective studies underline the value of schizotypy in high-risk research, but also point to the lack of evidence needed to better define the position of the construct of schizotypy within a developmental psychopathology perspective of emerging psychosis and schizophrenia-spectrum disorders.

Tachycardia is a strong predictor of cardiovascular events in the value trial

Objective: Tachycardia is associated with hypertension and is a predictor of cardiovascular events. The predictive effect of tachycardia might reflect its connection with hypertension. In this analysis of 15,245 VALUE study patients we explore whether tachycardia predicts cardiovascular endpoints in high risk hypertension and whether the in-trial blood pressure lowering modified the tachycardia - related risk. Methods: Heart rate from ECG readings at baseline and annually throughout the trial. Results: In the Cox Regression analysis the primary endpoint hazard ratio for a 10 beats per minute increment of baseline heart rate was 1.16 (1.12-1.2) p < 0.0001, 1.17 (1.13-1.22) p < 0.0001 and 1.22 (1.18-1.27) p < 0.0001 unadjusted, adjusted for baseline blood pressure and for blood pressure plus risk factors, respectively. Primary endpoints strikingly increased in the highest quintile of baseline heart rate (=/>79 beats). Primary endpoints in the highest heart rate quintile were 30 % higher in first, 55 % in second, 55 % in third, 52 % in fourth and 46 % in the fifth year of the study. The in-trial heart rate was also a potent predictor. The primary endpoint hazard ratios of highest heart rate quintile versus pooled lower 4 quintiles was (1.34-1.66) p < 0.0001 unadjusted, 1.52 (1.36-1.69) p <0.0001 adjusted for baseline blood pressure and risk factors and 1.52 (1.36-1.69) p < 0.0001 further adjusted for in trial pressure. The increase of primary events in the upper quintile of in-trial heart rate was 68% in the group with good and 63% in the group with inadequate blood pressure control (both p < 0.0001 by log rank test). Conclusions: 1./ Tachycardia is a short term marker and a long term predictor of adverse event in high risk hypertension. 2./ Tachycardia contributes to the residual cardiovascular risk regardless of the degree of BP control. We hypothesize heart rate lowering with appropriate drugs may further decrease the cardiovascular risk in patients with high risk hypertension and tachycardia.