Joint associations of physical activity and sedentary time with body mass index: A prospective study of mortality risk

Role of physical activity and sedentary behavior in venous thromboembolism: a systematic review and dose-response meta-analysis

Increasing studies have investigated the link between physical activity (PA) and sedentary behavior with venous thromboembolism (VTE) but the existing findings are not consistent and the independent relationship is uncertain. This meta-analysis aimed to comprehensively assess the shape of dose-response relationship between PA and sedentary behavior with VTE and further explore whether the relationship is independent after mutual adjustment. We systematically searched PubMed, Embase and Web of Science from inception to August 1, 2024. PA exposures were converted into MET-h/wk. Categorical meta-analyses and a cubic spline model were performed to evaluate the association between PA, sedentary behavior and VTE. Twenty-five articles including 31 studies were included. A curvilinear dose-response relationship between PA and VTE was observed, with steeper gradients even at lower PA levels. After adjustment for sedentary behavior, higher level of PA was independently associated with a reduced VTE risk (OR = 0.83, 95%CI:0.77-0.89). Based on population attributable fraction analyses, 2.37% (95%CI: 1.90-2.85%) of incident VTE could have been prevented if all adults had achieved half the PA minimum recommended level. A linear dose-response relationship between sedentary behavior and VTE risk was found, and there was a 2% higher risk of VTE (OR = 1.02, 95%CI: 1.00-1.03) for 1 h increment of sedentary behavior per day. After adjustment for PA, sedentary behavior was independently associated with an increased VTE risk (OR = 1.19, 95CI%:1.01-1.39). Our analyses demonstrated PA and sedentary time were indeed independently associated with the risk of VTE after mutually adjusting for sedentary time or PA, highlighting a unique perspective on their individual contributions. Further studies assessing the effects of different combinations of PA and sedentary time for assessing joint effects on VTE are needed.

County-level socio-environmental factors and obesity prevalence in the United States

AIMS

To investigate high-risk sociodemographic and environmental determinants of health (SEDH) potentially associated with adult obesity in counties in the United States using machine-learning techniques.

MATERIALS AND METHODS

We performed a cross-sectional analysis of county-level adult obesity prevalence (body mass index ≥30 kg/m2) in the United States using data from the Diabetes Surveillance System 2017. We harvested 49 county-level SEDH factors that were used in a classification and regression trees (CART) model to identify county-level clusters. The CART model was validated using a 'hold-out' set of counties and variable importance was evaluated using Random Forest.

RESULTS

Overall, we analysed 2752 counties in the United States, identifying a national median (interquartile range) obesity prevalence of 34.1% (30.2%, 37.7%). The CART method identified 11 clusters with a 60.8% relative increase in prevalence across the spectrum. Additionally, seven key SEDH variables were identified by CART to guide the categorization of clusters, including Physically Inactive (%), Diabetes (%), Severe Housing Problems (%), Food Insecurity (%), Uninsured (%), Population over 65 years (%) and Non-Hispanic Black (%).

CONCLUSION

There is significant county-level geographical variation in obesity prevalence in the United States, which can in part be explained by complex SEDH factors. The use of machine-learning techniques to analyse these factors can provide valuable insights into the importance of these upstream determinants of obesity and, therefore, aid in the development of geo-specific strategic interventions and optimize resource allocation to help battle the obesity pandemic.

All-cause mortality attributable to sitting time and physical inactivity in chilean adults

BACKGROUND

Evidence on all-cause mortality attributable to joint sitting time and physical inactivity is lacking. In this study, we estimated the proportion and number of deaths attributable to sitting time and physical inactivity in Chilean adults.

METHODS

A sample of 5834 adults aged 20-96 years from a 2016-2017 Chilean National Health Survey was included to describe the prevalence of 16 joint categories of sitting time and physical activity. Relative risks for the joint association of sitting time and physical inactivity were obtained from a meta-analysis of individual participant data. We retrieved the number of deaths in adults ≥ 20 years in 2019 from the Chilean Ministry of Health.

RESULTS

Participants with high sitting time (> 8 h/day) and low physical activity (< 2.5 MET-hour/week) were more likely to be women, 20-64 years, non-indigenous ethnicity, lived in the urban areas, had middle education level and monthly household income, and had public health insurance. Reducing sitting time and increasing physical activity to a theoretical minimum risk exposure level could prevent up to 11,470 deaths or 10.4% of all deaths. Increasing physical activity to >35.5 MET-hour/week and maintaining sitting time could prevent approximately 10,477 deaths or 9.5% of all deaths. Reducing sitting time to < 4 h/day and maintaining physical activity would not reduce the number of deaths (-3.4% or 38 deaths).

CONCLUSION

Reducing sitting time may be ancillary for preventing mortality. Therefore, increasing physical activity should be the primary focus of interventions and policies in Chile.