A most challenging task for scientists that are involved in the study of ageing is the development of a measure to quantify health status across populations and over time. In the present study, a Bayesian multilevel Item Response Theory approach is used to create a health score that can be compared across different waves in a longitudinal study, using anchor items and items that vary across waves. The same approach can be applied to compare health scores across different longitudinal studies, using items that vary across studies. Data from the English Longitudinal Study of Ageing (ELSA) are employed. Mixed-effects multilevel regression and Machine Learning methods were used to identify relationships between socio-demographics and the health score created. The metric of health was created for 17,886 subjects (54.6% of women) participating in at least one of the first six ELSA waves and correlated well with already known conditions that affect health. Future efforts will implement this approach in a harmonised data set comprising several longitudinal studies of ageing. This will enable valid comparisons between clinical and community dwelling populations and help to generate norms that could be useful in day-to-day clinical practice.

Although the etiology of hypertension-related organ damage remains poorly understood, it has recently been proposed that activated and adherent leukocytes may contribute to the pathogenesis of progressive organ injury in hypertension. The objective of this study was to determine whether the adherence and emigration of leukocytes in microvessels differ between spontaneously hypertensive and normotensive rats. Leukocyte adherence, rolling, and emigration as well as vessel diameter and erythrocyte velocity were monitored in mesenteric venules of age-matched normotensive and hypertensive rats. Measurements were obtained under baseline conditions and during superfusion of the mesentery with either platelet activating factor, leukotriene B 4 , or JV c -nitro-L-arginine-methyl ester, an inhibitor of nitric oxide synthesis. Tissue-associated myeloperoxidase activity, an index of the total tissue granulocyte population, was measured in various tissues of normotensive and hypertensive rats. Systemic arterial pressure and the circulating polymorphonuclear leukocyte count were elevated in hypertensive relative to normotensive rats. The number of adherent and emigrated leukocytes under baseline conditions did not differ between normotensive and hypertensive rats. Although the nitric oxide synthase inhibitor caused a similar rise in leukocyte adherence and emigration in both rat strains, the adhesive interactions elicited by either platelet activating factor or leukotriene B 4 were significantly blunted in hypertensive relative to normotensive rats. Flow cytometric analysis of whole-blood samples revealed a lower surface expression of CD1 lb/CD18 on leukocytes from hypertensive rats under stimulated conditions. Myeloperoxidase activity in mesentery and small and large intestine was low, whereas lung, spleen, and stomach values were high in hypertensive compared with normotensive rats. These results indicate that the altered leukocyte distribution in spontaneously hypertensive rats may result from a reduced capacity for leukocytes to adhere and emigrate in response to endogenous inflammatory stimuli such as leukotriene B 4 and platelet activating factor. Recently, these cells have received much attention as possible mediators of the endothelial cell injury and microvascular dysfunction associated with a number of cardiovascular diseases, including ischemic disorders 1 -3 and atherogenesis. 4 Leukocytes have also been implicated in the pathophysiology of hypertension. Schmid-Schonbein and coworkers 5 have proposed that hypertension-induced organ damage in the spontaneously hypertensive rat (SHR) might be related to the elevated blood leukocyte count and the greater proportion of spontaneously activated grarnilocytes circulating in these rats compared with normotensive Wistar-Kyoto

Background Research efforts to measure the concept of healthy ageing have been diverse and limited to specific populations. This diversity limits the potential to compare healthy ageing across countries and/or populations. In this study, we developed a novel measurement scale of healthy ageing using worldwide cohorts. Methods In the Ageing Trajectories of Health-Longitudinal Opportunities and Synergies (ATHLOS) project, data from 16 international cohorts were harmonized. Using ATHLOS data, an item response theory (IRT) model was used to develop a scale with 41 items related to health and functioning. Measurement heterogeneity due to intra-dataset specificities was detected, applying differential item functioning via a logistic regression framework. The model accounted for specificities in model parameters by introducing cohort-specific parameters that rescaled scores to the main scale, using an equating procedure. Final scores were estimated for all individuals and converted to T-scores with a mean of 50 and a standard deviation of 10. Results A common scale was created for 343 915 individuals above 18 years of age from 16 studies. The scale showed solid evidence of concurrent validity regarding various sociodemographic, life and health factors, and convergent validity with healthy life expectancy (r = 0.81) and gross domestic product (r = 0.58). Survival curves showed that the scale could also be predictive of mortality. Conclusions The ATHLOS scale, due to its reliability and global representativeness, has the potential to contribute to worldwide research on healthy ageing.