Suzanne J. Carroll

Validation of continuous clinical indices of cardiometabolic risk in a cohort of Australian adults

BackgroundIndicators of cardiometabolic risk typically include non-clinical factors (e.g., smoking). While the incorporation of non-clinical factors can improve absolute risk prediction, it is impossible to study the contribution of non-clinical factors when they are both predictors and part of the outcome measure. Metabolic syndrome, incorporating only clinical measures, seems a solution yet provides no information on risk severity. The aims of this study were: 1) to construct two continuous clinical indices of cardiometabolic risk (cCICRs), and assess their accuracy in predicting 10-year incident cardiovascular disease and/or type 2 diabetes; and 2) to compare the predictive accuracies of these cCICRs with existing risk indicators that incorporate non-clinical factors (Framingham Risk Scores).MethodsData from a population-based biomedical cohort (n = 4056) were used to construct two cCICRs from waist circumference, mean arteriole pressure, fasting glucose, triglycerides and high density lipoprotein: 1) the mean of standardised risk factors (cCICR-Z); and 2) the weighted mean of the two first principal components from principal component analysis (cCICR-PCA). The predictive accuracies of the two cCICRs and the Framingham Risk Scores were assessed and compared using ROC curves.ResultsBoth cCICRs demonstrated moderate accuracy (AUCs 0.72 – 0.76) in predicting incident cardiovascular disease and/or type 2 diabetes, among men and women. There were no significant differences between the predictive accuracies of the cCICRs and the Framingham Risk Scores.ConclusionscCICRs may be useful in research investigating associations between non-clinical factors and health by providing suitable alternatives to current risk indicators which include non-clinical factors.

Does Physical Activity Mediate the Associations Between Local-Area Descriptive Norms, Built Environment Walkability, and Glycosylated Hemoglobin?

Associations between local-area residential features and glycosylated hemoglobin (HbA1c) may be mediated by individual-level health behaviors. Such indirect effects have rarely been tested. This study assessed whether individual-level self-reported physical activity mediated the influence of local-area descriptive norms and objectively expressed walkability on 10-year change in HbA1c. HbA1c was assessed three times for adults in a 10-year population-based biomedical cohort (n = 4056). Local-area norms specific to each participant were calculated, aggregating responses from a separate statewide surveillance survey for 1600 m road-network buffers centered on participant addresses (local prevalence of overweight/obesity (body mass index ≥25 kg/m2) and physical inactivity (<150 min/week)). Separate latent growth models estimated direct and indirect (through physical activity) effects of local-area exposures on change in HbA1c, accounting for spatial clustering and covariates (individual-level age, sex, smoking status, marital status, employment and education, and area-level median household income). HbA1c worsened over time. Local-area norms directly and indirectly predicted worsening HbA1c trajectories. Walkability was directly and indirectly protective of worsening HbA1c. Local-area descriptive norms and walkability influence cardiometabolic risk trajectory through individual-level physical activity. Efforts to reduce population cardiometabolic risk should consider the extent of local-area unhealthful behavioral norms and walkability in tailoring strategies to improve physical activity.

Regional Differences in Correlates of Daily Walking among Middle Age and Older Australian Rural Adults: Implications for Health Promotion

Rural Australians are less physically active than their metropolitan counterparts, and yet very little is known of the candidate intervention targets for promoting physical activity in rural populations. As rural regions are economically, socially and environmentally diverse, drivers of regular physical activity are likely to vary between regions. This study explored the region-specific correlates of daily walking among middle age and older adults in rural regions with contrasting dominant primary industries. Participants were recruited through print and electronic media, primary care settings and community organisations. Pedometers were worn by 153 adults for at least four days, including a weekend day. A questionnaire identified potential intra-personal, social and environmental correlates of physical activity, according to a social ecological framework. Regression modelling identified independent correlates of daily walking separately in the two study regions. In one region, there were independent correlates of walking from all levels of the social ecological framework. In the other region, significant correlates of daily walking were almost all demographic (age, education and marital status). Participants living alone were less likely to be physically active regardless of region. This study highlights the importance of considering region-specific factors when designing strategies for promoting regular walking among rural adults.

Sex‐specific correlates of adult physical activity in an Australian rural community

OBJECTIVE Rural Australians have a higher likelihood of chronic disease and lower levels of physical activity than urban Australians. Little is known of the factors associated with physical activity among rural-dwelling Australians. This study sought to determine the correlates of physical activity among men and women of the South Australian Riverland region. DESIGN Cross-sectional survey. SETTING Regional area. PARTICIPANTS There are 299 randomly selected 18-65 year olds. MAIN OUTCOME MEASURES Determinations of insufficient and sufficient physical activity levels based on public health recommendations. RESULTS Using logistic regression: in men, sufficient physical activity was associated with reporting perceived sufficient physical activity for health (odds ratio 3.194 [1.703-5.989]), and having friends who encouraged physical activity (3.641 [1.450-9.141]). Men who reported insufficient time (0.350 [0.151-0.812]) and getting enough physical activity at their job (0.374 [0.199-0.702]) were less likely to be sufficiently active. In women, sufficient physical activity was associated with not being employed (2.929 [1.063-8.066]), higher self-efficacy (2.939 [1.118-7.726]) and having a regular physical activity routine (3.404 [1.829-6.337]). Older age (0.960 [0.929-0.995]), poorer self-rated health (0.233 [0.060-0.900]) and weekend sitting time (0.823 [0.692-0.980]) were negatively associated with sufficient physical activity for women. CONCLUSIONS Factors associated with physical activity in this rural adult population differed by sex. Sex-specific approaches to promote physical activity might have utility for this population. Strategies to enhance social connectedness among men and encourage physical activity outside of work can be warranted. Women can require programs to help them develop a regular physical activity routine and improve self-efficacy.