Cardiovascular risk prediction model development and assessment

The aim of this article is to review the development and assessment of cardiovascular risk prediction models and to discuss the predictive value of a risk factor as well as to introduce new assessment methods to evaluate a risk prediction model. Many cardiovascular risk prediction models have been developed during the past three decades. However, there has not been consistent agreement regarding how to appropriately assess a risk prediction model, especially when new markers are added to an existing model. The area under the receiver operating characteristic (ROC) curve has traditionally been used to assess the discriminatory ability of a risk prediction model. However, recent studies suggest that this method has its limitations and cannot be the sole approach to evaluate the usefulness of a new marker. New assessment methods are being developed to appropriately assess a risk prediction model and they will be gradually used in clinical and epidemiological studies.

Waist circumference, waist-hip ratio and BMI and their correlation with cardiovascular risk factors in Australian adults

Objectives. To compare body mass index (BMI), waist circumference and waist–hip ratio (WHR) as indices of obesity and assess the respective associations with type 2 diabetes, hypertension and dyslipidaemia.

Design and setting. A national sample of 11 247 Australians aged ≥25 years was examined in 2000 in a cross-sectional survey.

Main outcome measures. The examination included a fasting blood sample, standard 2-h 75-g oral glucose tolerance test, blood pressure measurements and questionnaires to assess treatment for dyslipidaemia and hypertension. BMI, waist circumference and WHR were measured to assess overweight and obesity.

Results. The prevalence of obesity amongst Australian adults defined by BMI, waist circumference and WHR was 20.8, 30.5 and 15.8% respectively. The unadjusted odds ratio for the fourth vs. first quartile of each obesity measurement showed that WHR had the strongest relationship with type 2 diabetes, dyslipidaemia (women only) and hypertension. Following adjustment for age, however, there was little difference between the three measures of obesity, with the possible exceptions of hypertension in women, where BMI had a stronger association, and dyslipidaemia in women and type 2 diabetes in men, where WHR was marginally superior.

Conclusions. Waist circumference, BMI and WHR identified different proportions of the population, as measured by both prevalence of obesity and cardiovascular disease (CVD) risk factors. Whilst WHR had the strongest correlations with CVD risk factors before adjustment for age, the three obesity measures performed similarly after adjustment for age. Given the difficulty of using age-adjusted associations in the clinical setting, these results suggest that given appropriate cut-off points, WHR is the most useful measure of obesity to use to identify individuals with CVD risk factors.

Potential of pharmacists to help reduce the burden of poorly managed cardiovascular risk

Introduction: Rural areas require better use of existing health professionals to ensure capacity to deliver improved cardiovascular outcomes. Community pharmacists (CPs) are accessible to most communities and can potentially undertake expanded roles in prevention of cardiovascular disease (CVD).

Objective: This study aims to establish frequency of contact with general practitioners (GPs) and CPs by patients at high risk of CVD or with inadequately controlled CVD risk factors.

Design, setting and participants: Population survey using randomly selected individuals from the Wimmera region electoral roll and incorporating a physical health check and self-administered health questionnaire. Overall, 1500 were invited to participate.

Results: The participation rate was 51% when ineligible individuals were excluded. Nine out of 10 participants visited one or both types of practitioner in the previous 12 months. Substantially more participants visited GPs compared with CPs (88.5% versus 66.8%). With the exception of excess alcohol intake, the median number of opportunities to intervene for every inadequately controlled CVD risk factor and among high risk patient groups at least doubled for the professions combined when compared with GP visits alone.

Conclusion: Opportunities exist to intervene more frequently with target groups by engaging CPs more effectively but would require a significant attitude shift towards CPs. Mechanisms for greater pharmacist integration into primary care teams should be investigated.

Cardiovascular risk factors and psychological distress in Australian farming communities

Objective:  To examine the prevalence of cardiovascular disease (CVD) risk factors, psychological distress and associations between physical and mental health parameters within a cohort of the Australian farming community.

Design:  Cross-sectional descriptive study.

Setting:  Farming communities across Australia.

Participants:  Data of men (n = 957) and women (n = 835) farmers from 97 locations across Australia were stratified into categories based on National Cholesterol Education Program guidelines.

Main outcome measure(s):  Prevalence of and interrelationship between overweight, obesity, dyslipidaemia, hypertension, diabetes risk and psychological distress.

Results:  There was a higher prevalence of overweight (42.5%, 95% confidence interval (CI), 34.2–50.8), obesity (21.8%, 95% CI, 18.3–25.3), abdominal adiposity (38.4% 95% CI, 24.5–52.5), hypertension (54.0%, 95% CI, 34.4–73.5) and diabetes risk (25.3%, 95% CI, 17.7–36.7) in the farming cohort compared with national data. There was also a positive significant association between the prevalence of psychological distress and obesity, abdominal adiposity, body fat percentage and metabolic syndrome in older (age ≥ 50 years) participants.

Conclusions:  This study group of farming men and women exhibited an increased prevalence of CVD risk factors and co-morbidities. The findings indicate a positive association between psychological distress and risk for developing CVD, particularly in the older farmers. If the younger cohort were to maintain elevated rates of psychological distress, then it is foreseeable that the next generation of farmers could experience poorer physical health than their predecessors.

Five-year change in cardiovascular risk factors according to education level : the Australian diabetes, obesity and lifestyle (AusDiab) study

Background: Lower socioeconomic status (SES) is strongly associated with a higher prevalence of major cardiovascular risk factors, but few studies have examined changes in these risk factors over time according to SES. We aimed to determine whether SES is a predictor of the change in cardiovascular risk factor levels in a contemporary Australian adult cohort

Methods: Participants in the population-based AusDiab study aged 25+ years who attended both baseline and 5-year follow-up examinations (n=5 954) were categorised according to their level of education at baseline. Cardiovascular risk factor data at both time points were ascertained through questionnaire and physical measurement. Analysis was stratified by gender.

Results: The mean levels of systolic blood pressure, total cholesterol and the prevalence of smoking decreased between the two time points across all educational categories. Increases were also seen in mean BMI and the prevalence of diabetes. For blood pressure, the smallest decrease was seen among men with lower education (age-adjusted difference from higher education 2.8 mmHg, 95% CI 1.0 to 4.6). For total cholesterol, the decrease was greatest among women with lower education (age-adjusted difference from higher education 0.11 mmol/l, 95% CI 0.19 to 0.02). Among those "not at risk" at baseline for each risk factor, women with lower education were more likely than those with higher education to progress to being "at risk" for BMI (age-adjusted odds ratio 1.60, 95% CI 1.09 to 2.35).

Conclusion: Educational gradients narrowed for total cholesterol in women, but widened for systolic blood pressure in men and remained static for other risk factors. Lower education was also associated with an earlier onset of overweight or obesity in women. Given current socioeconomic gradients in risk factors levels, these findings suggest that social inequalities in CVD will persist and may even widen in the future.

Incidence of cardiovascular risk factors by education level 2000-2005 : the Australian diabetes, obesity and lifestyle (AusDiab) cohort study

Lower socioeconomic status (SES) is associated with a higher prevalence of major risk factors for cardiovascular disease (CVD). However, few longitudinal studies have examined the association between SES and CVD risk factors over time. We aimed to determine whether SES, using education as a proxy, is associated with the onset of CVD risk factors over 5 years in an Australian adult cohort study.

Participants in the Australian Diabetes, Obesity and Lifestyle study (AusDiab) study aged 25 years and over who attended both baseline and 5-year follow-up examinations (n=5 967) were categorised according to educational attainment. Cardiovascular risk factor data at both time points were ascertained through questionnaire and physical measurement.

Women with lower education had a greater risk of progressing from normal weight to overweight or obesity than those with higher education (age-adjusted OR 1.57, 95% CI 1.06-2.31). Both men and women with lower education were more likely to develop diabetes (age-adjusted OR from higher education 1.75, 95% CI 1.14-2.71 and 3.01, 95% CI 1.26-7.20, respectively). A lower level of education was associated with a greater number of risk factors accumulated over time in women (OR of progressing from having two or less risk factors at baseline to three or more at follow up, 2.04, 95% 1.32-3.14).

In this Australian population-based study, lower educational attainment was associated with an increased risk of developing both individual and total CVD risk factors over a 5-year period. These findings suggest that SES inequalities in CVD will persist into the future.

Suboptimal management of cardiovascular risk factors in coronary heart disease patients in primary care occurs particularly in women

Background:  Patients with established coronary heart disease (CHD) are at the highest risk of further events. Despite proven therapies, secondary prevention is often suboptimal. General practitioners (GPs) are in an ideal position to improve secondary prevention.

Aim:  To contrast management of cardiovascular risk factors in patients with established CHD in primary care to those in clinical guidelines and according to gender.

Methods:  GPs throughout Australia were approached to participate in a programme incorporating a disease management software (mdCare) program. Participating practitioners (1258 GPs) recruited individual patients whose cardiovascular risk factor levels were measured.

Results:  The mdCare programme included 12 509 patients (58% male) diagnosed with CHD. Their mean age was 71.7 years (intra-quartile range 66–78) for men and 74 years (intra-quartile range 68–80) for women. Low-density-lipoprotein cholesterol was above target levels in 69% (2032) of women compared with 58% (2487) in men (P < 0.0001). There was also a higher proportion of women with total cholesterol above target levels (76%, 3592) compared with men (57%, 3787) (P < 0.0001). In patients who were prescribed lipid-lowering medication, 53% (2504) of men and 72% (2285) of women continued to have a total cholesterol higher than recommended target levels (P < 0.0001). Overall, over half (52%, 6538) had at least five cardiovascular risk factors (55% (2914) in women and 50% (3624) in men, P < 0.0001).

Conclusion:  This study found less intensive management of cardiovascular risk factors in CHD patients, particularly among women, despite equivalent cardiovascular risk. This study has shown that these patients have multiple risk factors where gender also plays a role.