Featured Commentary
Issue No.1 2012
Hot off the Press: Reducing lifetime cardiovascular risk
Key paper on lifetime cardiovascular risk
A proactive approach aimed at preventing cardiovascular (CV) risk factors to reduce lifetime risk of cardiovascular disease (CVD) is needed, according to the authors of a meta-analysis of 18 studies involving over 250,000 men and women.1 Among men aged 55 years or more, those with an optimal risk factor profile (nonsmokers without diabetes and optimal cholesterol and blood pressure) had a lower lifetime risk:
• For CV events by more than 3-fold
• For CV death, by 6-fold
• For coronary heart disease (CHD), by 10-fold, compared with those with two or more key risk factors.
Similar effects were observed for women aged 55 years (Fig 1).
Fig 1. Lifetime risk of cardiovascular (CV) and CHD events at age 55 years. Optimal risk factor management was defined as: total cholesterol <4.7 mmol/L, untreated blood pressure <120/80 mmHg, non-smoker and without diabetes
Furthermore, even if one major risk factor was not optimally managed, the lifetime risk of CV death among men aged 55 years was doubled (from 4.7% to 8.8%). Among women aged 55 years, the presence of one major risk factor almost doubled the lifetime risk of CV death (from 6.4% to 11.4%). Similar trends were observed for both black and white cohorts.
Yet despite the growing number of guidelines for CVD prevention, CV risk factor management is far from ideal. In this study, only about ≈3% of the total population aged 55 years (2.9% of men and 3.6% of women), were optimally managed for all key CV risk factors.
There is clearly much to be done to address these deficiencies. The authors make the case for redirecting management approaches to primordial prevention (i.e. preventing the development of CV risk factors) rather than primary prevention of existing CV risk factors to reduce the lifetime burden of CVD.
Personalised management: treating to risk or LDL cholesterol levels?
These data are in line with a perspective in Circulation: Cardiovascular Quality and Outcomes, in which experts recommend focusing on the individual’s global CV risk level rather than specific low-density lipoprotein (LDL cholesterol) targets.2 This debate will undoubtedly continue in advance of the publication of the revised National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) IV guidelines, expected this year.
One of the implications of this viewpoint is the need to take account of other risk factors beyond LDL cholesterol. This view would be consistent with a recent EAS Consensus Panel statement which has highlighted the high cardiovascular risk associated with non-LDL lipids, specifically elevated triglycerides and low plasma levels of HDL cholesterol, despite achievement of LDL cholesterol goal.3
Key Points
- These data highlight the need for optimal management to prevent CV risk factors (i.e. a holistic proactive approach) to reduce lifetime CV risk.
- However, it is also clear that the vast majority of individuals are not optimally managed.
- Management should therefore be redirected from primary prevention to primordial prevention to reduce the burden of cardiovascular disease.
Cardiovascular risk and socioeconomic status
The link between health, social class and wealth, initially made by the Whitehall Study,4 is now well recognised. In response to this, the World Health Organization (WHO) established the Commission on Social Determinants of Health (CSDH) in 2005 to address the challenge of health disparities due to difference in social and economic status.
Among the latest studies, the Cardiovascular Risk in Young Finns Study5 has highlighted the association between socioeconomic status and pre-clinical changes in atherosclerosis, as assessed by carotid intima-media thickness (CIMT). This is an ongoing epidemiological study of risk factors for atherosclerosis, from childhood to adulthood. The current study included data from 1,813 subjects (mean age at baseline 32 years, range 24-39 years) who completed follow-up at 21 and 27 years. Evaluation of socioeconomic status was by a questionnaire incorporating both educational level and occupation.
At baseline (21 year assessment), socioeconomic status was significantly and inversely associated with obesity (as measured by BMI and waist circumference), smoking, alcohol consumption, and insulin levels and directly associated with physical activity and high-density lipoprotein (HDL) cholesterol levels. Follow-up data 6 years later confirmed inverse associations between socioeconomic status and components of the metabolic syndrome (BMI, waist circumference, glucose and triglycerides) insulin and smoking, and a direct association with physical activity.
Lower socioeconomic status was significantly associated with increased CIMT. Education, a component of the measure of socioeconomic status, was significantly and inversely associated with the change in CIMT (p=0.002), even after adjustment for changes in lipids, blood pressure, BMI and baseline age, sex, CIMT and smoking (p=0.04).
While cardiovascular disease mortality is decreasing, the epidemics of obesity and diabetes now challenge these gains. These findings from the Cardiovascular Risk in Young Finns Study highlight the need for a renewed emphasis on efforts to target cardiovascular risk factor intervention particularly to individuals at lower socioeconomic status, who appear to be lagging behind those in higher groups.
Key Points
- Previous studies have highlighted a link between social class, wealth and cardiovascular disease.
- In this analysis from the Cardiovascular Risk in Young Finns Study, lower socioeconomic status, incorporating measures of educational level, is associated with an increase in cardiovascular risk factors and subclinical cardiovascular disease
- These data highlight the need to target risk factor interventions to this high-risk group.
Reinforcing this, recent data from Singapore,
6 show that individuals in lower socioeconomic groups are less likely to attend health screening programmes, consistent with data from other countries.
7 However, offering free and accessible clinics for screening hypertension, blood glucose and dyslipidemia provided tangible benefits, resulting in improved participation among economically deprived groups.
6
Overcoming sedentary behaviour
Physical activity is a key component of lifestyle intervention for cardiovascular disease prevention. Indeed, in a previous report from the I
NTERHEART study,
8 regular physical activity was shown to reduce the risk of acute myocardial infarction (MI) by 14%.
This recent analysis from the INTERHEART study provides further insights, investigating the effects of work and leisure physical activity.
9 The analysis shows that an increasingly sedentary lifestyle, resulting from technological advances and increased car ownership, is a key factor influencing cardiovascular risk. The implications from this analysis are clear: incorporate daily physical activity to reduce the risk of MI.
INTERHEART is a case-control study of risk factors for MI, involving 52 countries world-wide. The current analysis included data from 24,260 subjects, 10,043 with MI and 14,217 age and sex-matched controls. Physical activity during work and during leisure was assessed by questionnaire, with each component having four possible responses (ranging from mainly sedentary to heavy physical labour [for work-related activity] or from mainly sedentary to strenuous exercise [for leisure physical activity]). Subjects were also asked about the number of hours per week that they participated in physical activity, allowing this to be converted to a categorical variable ranging from 0 to >210 minutes per week.
Compared with individuals who were sedentary at work (reference group), subjects whose occupation involved light (e.g. walking on one level) or moderate (e.g. walking, climbing or lifting) physical activity had a lower risk MI (by 22%, 95% CI 14-29%, and 11%, 95% CI 1-20%, respectively. However, there was no association between heavy physical labour and risk of MI (odds ratio 1.02, 95% CI 0.88 to 1.19) (Fig 2). This was not attributable to differences in socioeconomic status as adjustments were made to the analysis to take account of this. Further analysis by type of country showed that mild work-related activity was protective against MI in middle and high income countries but not in low-income countries.
Additionally, any level of leisure physical activity was associated with decreased risk of MI (see Fig 2). The protective effect of moderate leisure activity extended across low, middle and high income countries.
Fig 2. Association between work- and leisure-related activity and risk of AMI
When analysed as a continuous variable, even minimal activity (30-60 minutes per week) decreased MI risk by 28% (95% CI 10-41%). This appeared to change only slightly in individuals who exercised more, and this effect persisted after adjustment for socio-demographic variables and conventional risk factors. However, it is possible that these findings may relate to the limitations of using a simple questionnaire as described previously.
Owning a car and TV was associated with an increased risk of MI of 27% (95% CI, 5-54%) compared with those who owned neither, although this association was mainly observed in low or middle-income countries.
The INTERHEART Investigators recognised a number of limitations with this analysis. Notably, assessment of exercise was qualitative and based on recall, and therefore subject to inaccuracy and bias. Additionally, the analysis excluded physical activity related to commuting, which may be especially relevant in cross-culture comparisons.
Despite these limitations, this analysis reinforces the value of physical activity in reducing the risk of MI, across different cultures. Consistent with recent guidelines, the analysis highlights the importance of daily exercise for at least 30 minutes in reducing the risk of MI.
Key Points
- Mild to moderate physical activity at work, and any physical activity during leisure time reduces the risk of MI in most regions of the world.
- Owning a car and TV promotes sedentary behaviour, although this is mainly seen in low to middle income countries.
- This report from the INTERHEART study reinforces the importance of incorporating daily moderate physical activity for cardiovascular disease prevention.
Latest US Obesity trends
Recent data from the National Health and Nutrition Examination Survey (NHANES)
10,11 suggest that there has been little change in the prevalence of obesity in the US over the last 12 years. In 2009-2010, about 36% of adults of adults and 17% of children and adolescents were obese. However, there is a suggestion that the prevalence of obesity may be increasing in young males, with a median of 22.5% of those aged 12-19 being obese in 2009-1010, compared with 21.6% in 1999-2000. Trend tests highlighted a particular effect in non-Hispanic black males, in whom there was an annual increase in the odds of obesity of 1.05 (95% CI 1.02-1.08) over 1999-2010.
Previous reports have raised the possibility that childhood obesity in the US may approximate adult levels by 2030. However, these data suggest that there appears to be a levelling off of the rate of increase. The reasons for this warrant further evaluation.