Evaluation of a new point-of-care diagnostic test measuring inflammation in emergency settings.

Erythrocyte aggregation kinetics is accelerated in diseases with a strong inflammation component. This study aimed to evaluate whether, in an emergency setting, a new point-of-care test measuring erythrocyte aggregation kinetics (EAK) can identify patients with underlying inflammation. Patients visiting an emergency department and needing a blood exam were successively included. EAK was measured at the point-of-care in 20 s directly on the blood samples collected in regular tubes without any manipulation. The primary measure was EAK's half-life during the first 5 s (EAK5s). Each patient's inflammation status was assessed blind to the EAK test results. Receiver Operating Characteristic (ROC) curves for inflammation status were built. 268 patients had their EAK5s measured, and a clear inflammation status was determined for 214 patients (65 had inflammation). Mean EAK5s were 2.18 s and 1.75 s for no inflammation and inflammation groups respectively (p < 0.001). EAK5s appears to be a better inflammation marker than C-Reactive protein (CRP), with an area under the ROC curve of 0.845 compared to 0.806 for CRP (p < 0.0001). The Youden threshold for prediction of inflammation was 1.86 s with 84.6% (78.5-89.9%) specificity and 70.8% (60-81.5%) sensitivity. Point-of-care EAK is an easily measured, immediately available marker of inflammation with a better predictive power than CRP's.

Description and validation of a new, simple, easy-to handle, point-of-care technique for measuring erythrocyte aggregation kinetics.

Erythrocyte aggregation (EA) is a physiological process by which erythrocytes reversibly stick together within the blood vessels. EA plays a major role in blood viscosity in vivo, thereby impacting blood flow to organs. EA is no doubt greatly important in both physiological and pathophysiological conditions, but the studies its importance calls for are complicated by the lack of a reliable and easy way to measure it. We have developed a new point-of-care technique which can very specifically measure EA initial kinetics (EAK) in 20 s directly on blood samples routinely collected in tubes commonly used in clinical settings. We present the results of the validation studies of this EAK test: A mono-exponential curve explains 99% of EAK variance. EAK is normally distributed in healthy individuals, with an interindividual 15% coefficient of variation and is stable for least one hour after blood collection. Intraindividual coefficient of variation is 2.6%. EA can now be easily measured in any clinical setting.

Exercise testing in the 21st century: from an "old" diagnostic to a novel health risk assessment tool.

Exercise testing was developed as a diagnostic tool in the first half of the 20th century when people, mostly men, paid the huge cost of coronary artery disease (CAD). Both the changing nature of CAD, which affects both men and women, and the aging of the population led to redefining the use of exercise testing. This test is now mainly used for evaluating overall prognosis. In parallel, new measurement such as exercise capacity and several components of the physiological reserve enrich the information which can be obtained from exercise testing. Therefore, exercise testing has become the major dynamic tool for predicting premature mortality far beyond traditional and disease specific risk markers. The present article reviews the main pieces of information which led to these changes and summarizes the elements which give exercise testing its utility.

Physical activity and aging: a life-long story.

The benefits of physical activity in preventing premature mortality have been established by a large set of epidemiological studies. These benefits have been shown both in middle-aged and elderly individuals. Furthermore, the reduction of acute events such as myocardial infarction observed with higher levels of physical activity together with the increase in disease-free life expectancy among the most active individuals supports physical activity's anti-aging effect. This review highlights two models supporting this effect. The first model describes the path to frailty and the second explains that immobilization is a stressor which triggers stress-responses responsible for many chronic diseases. Aging reduces the physiological reserve and can lead to frailty when this reserve cannot allow an appropriate adaptation of the aging body to environmental challenges. The components of this physiological reserve can easily be measured by cardiorespiratory testing. Among them are heart rate reserve and VO(2max), the maximal body oxygen consumption. The opposite effects of exercise training and aging on the physiological reserve are detailed. Underlying mechanisms of both exercise training and aging are described. Sedentary lifestyle accelerates the effects of aging in susceptible individuals. Sedentary lifestyle induces mechanisms which lead to risk factors of chronic diseases and, eventually, to premature death. These pathological mechanisms and their consequences constitute the sedentary lifestyle syndrome.

Disease prevention--should we target obesity or sedentary lifestyle?

Obesity is a major health challenge facing the modern world. Some evidence points to obesity itself as the main driver of premature mortality. We propose that this view is oversimplified. For example, high levels of physical activity and cardiorespiratory fitness are associated with lower mortality, even in those who are overweight or obese. To address this issue, we combine epidemiological and physiological evidence in a new paradigm that integrates excess calorie intake, sedentary behavior, and a maladaptive response to stress. Human physiology is optimized to allow large distances to be covered on foot every day in order to find enough food to sustain brain metabolism. Furthermore, when the body is immobilized by an injury, it triggers efficient life-saving metabolic and inflammatory responses. Both these critical adaptations are, however, confounded by a sedentary lifestyle. The implications of these issues for clinical trial design and epidemiologic data analysis are discussed in this article.

Predicting renal replacement therapy and mortality in CKD.

BACKGROUND: Prognostic risk scores can help clinicians intervene on higher risk patients and counsel them. Our objective is to identify characteristics that predict the rate of progression to renal replacement therapy (RRT) and evaluate how those characteristics predict mortality and a composite end point (RRT and mortality). STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: We conducted the study at Kaiser Permanente Northwest, a health maintenance organization. We followed up members with an estimated glomerular filtration rate (eGFR) that indicated chronic kidney disease (2 eGFRs < 60 mL/min/1.73 m(2) [<1.0 mL/s/1.73 m(2)] at least 90 days apart). PREDICTORS: We measured baseline clinical characteristics between January 1997 and June 2000 by using electronic medical records and patients' histories of hospitalization. OUTCOMES & MEASUREMENTS: We calculated adjusted hazard ratios and concordance statistics for progression to RRT, mortality, and the composite by using Cox regression. RESULTS: Patients (n = 6,541) were followed up for up to 5 years. We observed 1.6 progressions to RRT/100 person-years and 11.4 deaths/100 person-years. The 6 characteristics of age, sex, eGFR, diabetes, hypertension, and anemia predicted RRT effectively (c statistic, 0.91). However, hypertension and age predicted in the opposite direction for mortality and its composite end point. The c statistic decreased: mortality (0.70), mortality and RRT (0.71). LIMITATIONS: Characteristics were measured without a protocol; extensive missing data prevented the evaluation of known risk factors (eg, proteinuria). CONCLUSIONS: Predicting RRT effectively requires a separate risk score. Predicting the composite end point would favor characteristics that predict mortality because it is 7 times as common as RRT.