Clinical Trial Service Unit

About: Clinical Trial Service Unit is a based out in . It is known for research contribution in the topics: Population & Stroke. The organization has 428 authors who have published 1387 publications receiving 181920 citations.

Body Fat Distribution and Systolic Blood Pressure in 10,000 Adults with Whole-Body Imaging: UK Biobank and Oxford BioBank

Abstract: Objective This study aimed to quantify the associations of regional fat mass and fat-free mass with systolic blood pressure. Methods This analysis combined individual participant data from two large-scale imaging studies: UK Biobank and Oxford BioBank. In both studies, participants were interviewed and measured, and they underwent dual-energy x-ray absorptiometry imaging. Linear regression was used to relate systolic blood pressure to anthropometric measures of adiposity (BMI, waist circumference, and waist to hip ratio) and dual-energy x-ray absorptiometry-derived measures of body composition (visceral android fat, subcutaneous android fat, subcutaneous gynoid fat, and fat-free mass). Results Among 10,260 participants (mean age 49; 96% white), systolic blood pressure was positively associated with visceral android fat (3.2 mmHg/SD in men; 2.8 mmHg/SD in women) and fat-free mass (1.92 mmHg/SD in men; 1.64 mmHg/SD in women), but there was no evidence of an association with subcutaneous android or gynoid fat. Associations of systolic blood pressure with BMI were slightly steeper than those with waist circumference or waist to hip ratio; these associations remained unchanged following adjustment for fat-free mass, but adjustment for visceral android fat eliminated associations with waist circumference and waist to hip ratio and more than halved associations with BMI. Conclusions This analysis indicates that visceral fat is the primary etiological component of excess adiposity underlying the development of adiposity-related hypertension.

Adiposity in relation to age at menarche and other reproductive factors among 300 000 Chinese women: findings from China Kadoorie Biobank study

Abstract: Background Adiposity is increasing rapidly in China but little is known about the relevance to it of women's reproductive factors, which differ inter-generationally and from that in the West. We assess associations of adiposity with life-course reproductive factors in Chinese women. Methods In 2004-08, the nationwide China Kadoorie Biobank recruited 303 000 women aged 30-79 (mean 50) years from 10 diverse regions. Multivariable linear regression was used to examine associations of reproductive factors (e.g. age at menarche/first birth/menopause, parity, breastfeeding and reproductive years) with measures of general [e.g. body mass index (BMI)] and central [e.g. waist circumference (WC)] adiposity in adulthood. Results Overall, the mean BMI was 23.7 (standard deviation 3.3) kg/m 2 , mean age at menarche was 15 (2) years and nearly all had given birth (99%) and breastfed children (98%). Adiposity was associated inversely with age at menarche and at first birth, with 0.19 and 0.05 kg/m 2 lower BMI and 0.38 and 0.12 cm lower WC per 1-year delay respectively ( P < 0.001). Among 128 259 post-menopausal women, adiposity was associated positively with age at menopause and reproductive years, with 0.05 and 0.07 kg/m 2 higher BMI and 0.12 and 0.17 cm higher WC per 1-year increase, respectively ( P < 0.001). The proportion with overweight/obesity had similar associations with these reproductive factors. Adiposity had a non-linear positive association with parity, but no association with breastfeeding duration. Conclusion Among Chinese women, earlier age at menarche and at first birth, later age at menopause and longer reproductive years were independently associated with increased adiposity late in life.

Selenium and Prostate Cancer: Analysis of Individual Participant Data From Fifteen Prospective Studies

Abstract: Background: Some observational studies suggest that a higher selenium status is associated with a lower risk of prostate cancer but have been generally too small to provide precise estimates of associations, particularly by disease stage and grade. Methods: Collaborating investigators from 15 prospective studies provided individual-participant records (from predominantly men of white European ancestry) on blood or toenail selenium concentrations and prostate cancer risk. Odds ratios of prostate cancer by selenium concentration were estimated using multivariable-adjusted conditional logistic regression. All statistical tests were two-sided. Results: Blood selenium was not associated with the risk of total prostate cancer (multivariable-adjusted odds ratio [OR] per 80 percentile increase = 1.01, 95% confidence interval [CI] = 0.83 to 1.23, based on 4527 case patients and 6021 control subjects). However, there was heterogeneity by disease aggressiveness (ie, advanced stage and/or prostate cancer death, Pheterogeneity = .01), with high blood selenium associated with a lower risk of aggressive disease (OR = 0.43, 95% CI = 0.21 to 0.87) but not with nonaggressive disease. Nail selenium was inversely associated with total prostate cancer (OR = 0.29, 95% CI = 0.22 to 0.40, Ptrend < .001, based on 1970 case patients and 2086 control subjects), including both nonaggressive (OR = 0.33, 95% CI = 0.22 to 0.50) and aggressive disease (OR = 0.18, 95% CI = 0.11 to 0.31, Pheterogeneity = .08). Conclusions: Nail, but not blood, selenium concentration is inversely associated with risk of total prostate cancer, possibly because nails are a more reliable marker of long-term selenium exposure. Both blood and nail selenium concentrations are associated with a reduced risk of aggressive disease, which warrants further investigation.

The benefit of alcohol in moderation

Abstract: Small amounts of alcohol were held to be beneficial in the 19th century, but the idea died out. Scientific evidence that moderate amounts prolonged life, published in 1926, was ignored. Further evidence accumulated from the early 1950s but the belief that alcohol was only harmful had become so ingrained that the idea has been taken seriously only since the early 1980s. Now, the evidence that small amounts reduce the risk of vascular disease by about a third and reduce total mortality in middle and old age is massive. Alternative explanations for the observed inverse relationships have been ruled out and beneficial effects have been shown to be biologically plausible. The reduction in mortality is mainly attributable to ischaemic heart disease and cerebral thrombosis, but some other diseases may also contribute to it. The increasing mortality with larger amounts is attributable to many causes that have long been recognized. The optimum level varies with sex and age and may be zero under about age 45 years. The benefit is directly due to ethanol and the extra benefit attributed to wine is due to the pattern of drinking. Public policy needs to take account of medical and social effects other than mortality and will vary in different communities depending on background patterns of injury and disease.

Use of Causal Diagrams to Inform the Design and Interpretation of Observational Studies: An Example from the Study of Heart and Renal Protection (SHARP)

Abstract: Observational studies often seek to estimate the causal relevance of an exposure to an outcome of interest. However, many possible biases can arise when estimating such relationships, in particular bias because of confounding. To control for confounding properly, careful consideration of the nature of the assumed relationships between the exposure, the outcome, and other characteristics is required. Causal diagrams provide a simple graphic means of displaying such relationships, describing the assumptions made, and allowing for the identification of a set of characteristics that should be taken into account (i.e., adjusted for) in any analysis. Furthermore, causal diagrams can be used to identify other possible sources of bias (such as selection bias), which if understood from the outset, can inform the planning of appropriate analyses. In this article, we review the basic theory of causal diagrams and describe some of the methods available to identify which characteristics need to be taken into account when estimating the total effect of an exposure on an outcome. In doing so, we review the concept of collider bias and show how it is inappropriate to adjust for characteristics that may be influenced, directly or indirectly, by both the exposure and the outcome of interest. A motivating example is taken from the Study of Heart and Renal Protection, in which the relevance of smoking to progression to ESRD is considered.