Non-exercise equations to estimate fitness in white European and South Asian men

© 2015 American College of Sports Medicine PURPOSE: Cardiorespiratory fitness is a strong, independent predictor of health, whether it is measured in an exercise test or estimated in an equation. The purpose of this study was to develop and validate equations to estimate fitness in middle-aged white European and South Asian men. METHODS: Multiple linear regression models (n=168, including 83 white European and 85 South Asian men) were created using variables that are thought to be important in predicting fitness (VO2 max, mL⋅kg⋅min): age (years); BMI (kg·m); resting heart rate (beats⋅min); smoking status (0=never smoked, 1=ex or current smoker); physical activity expressed as quintiles (0=quintile 1, 1=quintile 2, 2=quintile 3, 3=quintile 4, 4=quintile 5), categories of moderate- to vigorous-intensity physical activity (0=150-225 min⋅wk, 3=>225-300 min⋅wk, 4=>300 min⋅wk), or minutes of moderate- to vigorous-intensity physical activity (min⋅wk); and, ethnicity (0=South Asian, 1=white). The leave-one-out-cross-validation procedure was used to assess the generalizability and the bootstrap and jackknife resampling techniques were used to estimate the variance and bias of the models. RESULTS: Around 70% of the variance in fitness was explained in models with an ethnicity variable, such as: VO2 max = 77.409 - (age*0.374) – (BMI*0.906) – (ex or current smoker*1.976) + (physical activity quintile coefficient) – (resting heart rate*0.066) + (white ethnicity*8.032), where physical activity quintile 1 is 1, 2 is 1.127, 3 is 1.869, 4 is 3.793, and 5 is 3.029. Only around 50% of the variance was explained in models without an ethnicity variable. All models with an ethnicity variable were generalizable and had low variance and bias. CONCLUSION: These data demonstrate the importance of incorporating ethnicity in non-exercise equations to estimate cardiorespiratory fitness in multi-ethnic populations

Postprandial studies of moderate exercise and triacylglycerol metabolism

Exaggerated postprandial lipaemia has been implicated in the development of atherosclerosis. Thus, by reducing postprandial TAG concentrations, exercise may play a role in delaying atherogenic progression. This thesis sought to explore the qualitative nature of, and the mechanisms behind, the moderate exercise-induced attenuation to postprandial lipaemia. Before the experimental studies commenced, a reproducibility study was undertaken. This showed that in a group of eight middle-aged men, the postprandial plasma TAG response differed by only 1.9 ± 5.1 % (mean ± standard error) on a testretest basis, indicating that the oral fat tolerance test had enough precision to detect the effect of exercise on TAG metabolism. Previous work suggested that the exercise-induced reduction to lipaemia was linked to the energy expended by exercise. As the attenuation may have been mediated by energy deficit, rather than exercise per se, a study comparing the effect of a 90-minute moderate exercise session with an equivalent dietary-induced energy deficit on postprandial lipid metabolism was undertaken, in a group of eleven postmenopausal women. This showed that the reduction in postprandial lipaemia elicited by exercise was far greater than that elicited by intake-restriction (20 % vs. 7 %). The second experimental study aimed to establish the effect of a 90-minute moderate exercise session on postprandial chylomicron- and very-Iow-density lipoprotein (VLDL)-TAG concentrations, and its effect on exogenous (through use of a l3e-Iabelled lipid) and endogenous fat oxidation, in a group oftwelve middle-aged men. Exercise reduced postprandial lipaemia by 23 %, and over three-quarters of this reduction was due to lower VLDL-TAG concentrations. Increases in endogenous fat oxidation accounted for over half of the increase in postprandial fat oxidation. In the third experimental study, the effect of a 90-minutes moderate exercise session on Intralipid clearance, and postprandial lipaemia, was determined in a group of eight middle-aged men. Exercise attenuated postprandial lipaemia by 18 %, but did not increase Intralipid clearance. Taken together, these data imply that moderate exercise predominantly reduced postprandial TAG concentrations by reducing hepatic VLDL secretion, rather than increasing TAG clearance, and this effect is not mediated by whole-body energy deficit. In addition, this work has shown that moderate exercise is effective at attenuating postprandial lipaemia in middle-aged men and postmenopausal women

Beta Cell Function, Hepatic Insulin Clearance, and Insulin Sensitivity in South Asian and Nordic Women after Gestational Diabetes Mellitus

South Asians have higher risk of type 2 diabetes after gestational diabetes mellitus (GDM) than Nordic women; however the mechanisms behind this difference remain unclear. We investigated insulin sensitivity, beta cell function, and hepatic insulin clearance, in 179 South Asian and 108 Nordic women ~17 months after GDM (mean age 35.3 years and BMI 29.1 kg/m2), via an oral glucose tolerance test using deconvolution of C-peptide kinetics. 31% of South Asian and 53% of Nordic participants were normoglycemic at the time of measurement. South Asian women had higher area under the curve (AUC) for glucose, pre-hepatic insulin, peripheral insulin, and lower levels of insulin sensitivity, disposition index, and fasting hepatic insulin clearance compared with Nordic women. In the group with prediabetes or diabetes, South Asian women displayed similar AUC for glucose and pre-hepatic insulin, but higher AUC for peripheral insulin, and lower levels of disposition index, and fasting hepatic insulin clearance compared with Nordic women. The waist-to-height ratio mediated ~25-40% of the ethnic differences in insulin sensitivity in normoglycemic women. Overall, our novel data showed that normoglycemic South Asian women after GDM displayed lower insulin secretion for a given insulin resistance, and lower hepatic insulin clearance compared with Nordic women. South Asian women are at high risk of developing type 2 diabetes after GDM, and preventive efforts should be prioritized. </p

The associations of sugar-sweetened, artificially sweetened and naturally sweet juices with all-cause mortality in 198,285 UK Biobank participants: a prospective cohort study

Background: Recent efforts to address the obesity epidemic have focused on sugar consumption, especially sugar-sweetened beverages. However, sugar takes many forms, is only one contributor to overall energy consumption and is correlated with other health-related lifestyle factors. The objective was to investigate the associations with allcause mortality of sugar- and artificially sweetened beverages and naturally sweet juices. Methods: Setting: UK Biobank, UK. Participants joined the UK Biobank study from 2006 to 2010 and were followed up until 2016; 198,285 men and women aged 40–69 years were eligible for this study (40% of the UK Biobank), of whom 3166 (1.6%) died over a mean of 7 years follow-up. Design: prospective population-based cohort study. Exposure variables: dietary consumption of sugar-sweetened beverages, artificially sweetened beverages, naturally sweet juices (100% fruit/vegetable juices) and total sugar intake, self-reported via 24-h dietary assessment tool completed between 2009 and 2012. Main outcome: all-cause mortality. Cox regression analyses were used to study the association between the daily intake of the above beverages and all-cause mortality. Models were adjusted for socio-demographic, economic, lifestyle and dietary confounders. Results: Total energy intake, total sugar intake and percentage of energy derived from sugar were comparable among participants who consumed > 2/day sugar-sweetened beverages and > 2/day fruit/vegetable juices (10,221 kJ/day versus 10,381 kJ/day; 183 g versus 190 g; 30.6% versus 31.0%). All-cause mortality was associated with total sugar intake (highest quintile adj. HR 1.28, 95% CI 1.06–1.55) and intake of sugar-sweetened beverages (> 2/day adj. HR 1.84, 95% CI 1.42–2.37) and remained so in sensitivity analyses. An association between artificially sweetened beverage intake and mortality did not persist after excluding deaths in the first 2 years of follow-up (landmark analysis) nor after excluding participants with recent weight loss. Furthermore, the inverse association between fruit/vegetable juice intake and mortality did not persist after additional adjustment for a diet quality score. Conclusions: Higher mortality is associated with sugar-sweetened beverages specifically. The lack of an adverse association with fruit/vegetable juices suggests that source of sugar may be important and the association with artificially sweetened beverage may reflect reverse causation. Conclusions: Higher mortality is associated with sugar-sweetened beverages specifically. The lack of an adverse association with fruit/vegetable juices suggests that source of sugar may be important and the association with artificially sweetened beverage may reflect reverse causation

Design and baseline characteristics of the PODOSA (Prevention of Diabetes & Obesity in South Asians) trial: a cluster, randomised lifestyle intervention in Indian and Pakistani adults with impaired glycaemia at high risk of developing type 2 diabetes

To describe the design and baseline population characteristics of an adapted lifestyle intervention trial aimed at reducing weight and increasing physical activity in people of Indian and Pakistani origin at high risk of developing type 2 diabetes

Recruiting South Asians to a lifestyle intervention trial: experiences and lessons from PODOSA (Prevention of Diabetes & Obesity in South Asians)

Background: Despite the growing emphasis on the inclusion of ethnic minority patients in research, there is little published on the recruitment of these populations especially to randomised, community based, lifestyle intervention trials in the UK. Methods: We share our experience of recruitment to screening in the PODOSA (Prevention of Diabetes and Obesity in South Asians) trial, which screened 1319 recruits (target 1800) for trial eligibility. A multi-pronged recruitment approach was used. Enrolment via the National Health Service included direct referrals from health care professionals and written invitations via general practices. Recruitment within the community was carried out by both the research team and through our partnerships with local South Asian groups and organisations. Participants were encouraged to refer friends and family throughout the recruitment period. Results: Health care professionals referred only 55 potential participants. The response to written invitations via general practitioners was 5.2%, lower than reported in other general populations. Community orientated, personal approaches for recruitment were comparatively effective yielding 1728 referrals (82%) to the screening stage. Conclusions: The PODOSA experience shows that a community orientated, personal approach for recruiting South Asian ethnic minority populations can be successful in a trial setting. We recommend that consideration is given to cover recruitment costs associated with community engagement and other personalised approaches. Researchers should consider prioritising approaches that minimise interference with professionals’ work and, particularly in the current economic climate, keep costs to a minimum. The lessons learned in PODOSA should contribute to future community based trials in South Asians

Derivation and validation of a 10-year risk score for symptomatic abdominal aortic aneurysm

BACKGROUND: Abdominal aortic aneurysm (AAA) can occur in patients who are ineligible for routine ultrasound screening. A simple AAA risk score was derived and compared with current guidelines used for ultrasound screening of AAA. METHODS: United Kingdom Biobank participants without previous AAA were split into a derivation cohort (n=401820, 54.6% women, mean age 56.4 years, 95.5% White race) and validation cohort (n=83816). Incident AAA was defined as first hospital inpatient diagnosis of AAA, death from AAA, or an AAA-related surgical procedure. A multivariable Cox model was developed in the derivation cohort into an AAA risk score that did not require blood biomarkers. To illustrate the sensitivity and specificity of the risk score for AAA, a theoretical threshold to refer patients for ultrasound at 0.25% 10-year risk was modeled. Discrimination of the risk score was compared with a model of US Preventive Services Task Force (USPSTF) AAA screening guidelines. RESULTS: In the derivation cohort, there were 1570 (0.40%) cases of AAA over a median 11.3 years of follow-up. Components of the AAA risk score were age (stratified by smoking status), weight (stratified by smoking status), antihypertensive and cholesterol-lowering medication use, height, diastolic blood pressure, baseline cardiovascular disease, and diabetes. In the validation cohort, over 10 years of follow-up, the C-index for the model of the USPSTF guidelines was 0.705 (95% CI, 0.678–0.733). The C-index of the risk score as a continuous variable was 0.856 (95% CI, 0.837–0.878). In the validation cohort, the USPSTF model yielded sensitivity 63.9% and specificity 71.3%. At the 0.25% 10-year risk threshold, the risk score yielded sensitivity 82.1% and specificity 70.7% while also improving the net reclassification index compared with the USPSTF model +0.176 (95% CI, 0.120–0.232). A combined model, whereby risk scoring was combined with the USPSTF model, also improved prediction compared with USPSTF alone (net reclassification index +0.101 [95% CI, 0.055–0.147]). CONCLUSIONS: In an asymptomatic general population, a risk score based on patient age, height, weight, and medical history may improve identification of asymptomatic patients at risk for clinical events from AAA. Further development and validation of risk scores to detect asymptomatic AAA are needed

Effect of a lifestyle intervention on weight change in south Asian individuals in the UK at high risk of type 2 diabetes: a family-cluster randomised controlled trial

The susceptibility to type 2 diabetes of people of south Asian descent is established, but there is little trial-based evidence for interventions to tackle this problem. We assessed a weight control and physical activity intervention in south Asian individuals in the UK

Ethnic differences in prevalence of actionable HbA1c levels in UK biobank: implications for screening

Introduction Early detection and treatment of diabetes as well as its prevention help lessen longer-term complications. We determined the prevalence of pre-diabetes and undiagnosed diabetes in the UK Biobank and standardized the results to the UK general population. Research design and methods This cross-sectional study analyzed baseline UK Biobank data on plasma glycated hemoglobin (HbA1c) to compare the prevalence of pre-diabetes and undiagnosed diabetes mellitus in white, South Asian, black, and Chinese participants. The overall and ethnic-specific results were standardized to the UK general population aged 40–70 years of age. Results Within the UK Biobank, the overall crude prevalence was 3.6% for pre-diabetes, 0.8% for undiagnosed diabetes, and 4.4% for either. Following standardization to the UK general population, the results were similar at 3.8%, 0.8%, and 4.7%, respectively. Crude prevalence was much higher in South Asian (11.0% pre-diabetes; 3.6% undiagnosed diabetes; 14.6% either) or black (13.8% pre-diabetes; 3.0% undiagnosed diabetes; 16.8% either) participants. Only six middle-aged or old-aged South Asian individuals or seven black would need to be tested to identify an HbA1c result that merits action. Conclusions Single-stage population screening for pre-diabetes or undiagnosed diabetes in middle-old or old-aged South Asian and black individuals using HbA1c could be efficient and should be considere

Remote history of VTE is associated with severe COVID-19 in middle and older age: UK biobank cohort study

Background: Venous thromboembolism (VTE) is a common, life-threatening complication of COVID-19 infection. COVID-19 risk-prediction models include a history of VTE. However, it is unclear whether remote history (>9 years previously) of VTE also confers increased risk of COVID-19. Objectives: To investigate possible association between VTE and COVID-19 severity, independent of other risk factors. Methods: Cohort study of UK Biobank participants recruited between 2006 and 2010. Baseline data, including history of VTE, were linked to COVID-19 test results, COVID-19-related hospital admissions, and COVID-19 deaths. The risk of COVID-19 hospitalization or death was compared for participants with a remote history VTE versus without. Poisson regression models were run univariately then adjusted stepwise for sociodemographic, lifestyle, and comorbid covariates