C-reactive protein, established risk factors and social inequalities in cardiovascular disease - the significance of absolute versus relative measures of disease

The effect of smoking on carotid intima-media thickness progression rate and rate of lumen diameter reduction

OBJECTIVE

The purpose of the study was to investigate the long-term associations between smoking habits, environmental tobacco smoke exposure (ETS), carotid intima-media thickness (IMT) progression rate, and rate of lumen diameter reduction in the carotid artery during a 16-year follow-up. Another objective was to investigate if an effect of smoking on progression rate could be explained by increased low grade inflammation.

METHODS

The study population included 2992 middle-aged men and women in the 1991-1994 (baseline) and the 2007-2012 (re-examination) investigation of the Malmö Diet and Cancer Study cardiovascular cohort. Associations between smoking, progression of carotid IMT and lumen diameter reduction due to plaque protrusion were assessed by linear regression.

RESULTS

IMT progression rates and rate of lumen diameter reduction increased from never smokers with no ETS through former, moderate and heavy smokers, even after adjustment for traditional risk factors (e.g., differences in yearly progression rates (mm/year) of maximal IMT in the carotid bifurcation compared to never smokers; former smokers 0.0074 (95% CI: 0.0018-0.0129), moderate smokers 0.0106 (95% CI: 0.0038-0.0175), and heavy smokers 0.0146 (95% CI: 0.0061-0.0230)). Former smokers showed distinct lowering of progression rates after more than five years since smoking cessation. Smoking and former smoking was associated with increased low grade inflammation, however, the effect of smoking on atherosclerotic progression rate remained fairly unchanged after such adjustment.

CONCLUSION

The effect of smoking and former smoking on carotid IMT progression rates and change in lumen reduction due to plaque protrusion could not be explained by differences in traditional risk factors or low grade inflammation.

Risk Factors of Coronary Artery Disease in Secondary Prevention--Results from the AtheroGene--Study

Background

Risk factors are important in cardiovascular (CV) medicine for risk stratification of patients. We aimed to compare the traditional risk factors to clinical variables for the prediction of secondary cardiovascular events.

Methods and Results

For this study, 3229 patients with known coronary artery disease (CAD) were included. We calculated whether the traditional risk factors, diabetes mellitus, increased LDL/HDL ratio, arterial hypertension and smoking alone and in combination with the clinical variables, ejection fraction, creatinine clearance, multi-vessel disease and CRP concentration predict the outcome cardiovascular death or non-fatal myocardial infarction (N = 432) during the mean follow-up time of 4.2 ± 2.0 years. In this cohort diabetes mellitus was the risk factor with the strongest influence regarding occurrence of secondary events (hazard ratio; HR:1.70, confidence interval; CI 95%: 1.36-2.11; P<0.0001), followed by LDL/HDL ratio and smoking. However, risk stratification is further improved by using additional clinical variables like ejection fraction (HR:3.30 CI 95%:2.51-4.33; P>0.0001) or calculated creatinine clearence (Cockroft-Gault formula) (HR:2.26 CI 95%:1.78-2.89; P<0.0001). Further ameliorating risk stratification from the clinical variables were CRP and multi-vessel disease. The most precise risk prediction was achieved when all clinical variables were added to the CV risk factors.

Conclusion

Diabetes mellitus has the strongest influence to predict secondary cardiovascular events in patients with known CAD. Risk stratification can further be improved by adding CV risk factors and clinical variables together. Control of risk factors is of paramount importance in patients with known CAD, while clinical variables can further enhance prediction of events.

Social status, glucocorticoids, immune function, and health: can animal studies help us understand human socioeconomic-status-related health disparities?

For humans in developed nations, socioeconomic status (SES)--relative income, education and occupational position in a society--is a strong predictor of morbidity and mortality rates, with increasing SES predicting longer life span (e.g. Marmot et al., 1991). Mechanisms underlying this relationship have been examined, but the relative role of each mechanism still remains unknown. By understanding the relative role of specific mechanisms that underlie dramatic health disparities between high and low social status individuals we can begin to identify effective, targeted methods to alleviate health disparities. In the current paper, we take advantage of a growing number of animal studies that have quantified biological health-related correlates (glucocorticoid production and immune function) of social status and compare these studies to the current literature on human SES and health to determine if and how animal studies can further our understanding of SES-associated human health disparities. Specifically, we compared social-status related glucocorticoid production and immune function in humans and animals. From the review, we show that our present understanding of the relationships between social status and glucocorticoid production/immune function is still growing, but that there are already identifiable parallels (and non-parallels) between humans and animals. We propose timely areas of future study focused on (1) specific aspects of social status that may influence stress-related physiology, (2) mechanisms underlying long-term influences of social status on physiology and health, and (3) intervention studies to alleviate potentially negative physiological correlates of social status.

Association of Helicobacter pylori infection with acute myocardial infarction

OBJECTIVES

Helicobacter pylori infection has been linked to cardiovascular diseases (CVD) and several studies have reported its positive association with inflammatory response after acute myocardial infarction (AMI). On account of the importance of the inflammatory process in the development of CVD, we decided to examine the seroprevalence of H. pylori, the prevalence of CVD risk in the more virulent strains bearing the cytotoxin-associated protein (CagA), and the changes in C-reactive protein (CRP) as an inflammatory marker in Iranian patients with AMI.

METHODS

A case-control study was designed to determine the seropositivity status of H. pylori and CagA in blood samples obtained from 500 patients with AMI and 500 control individuals without any evidence of clinical CVD. Serum and peripheral blood mononuclear cells were analyzed using the enzyme-linked immunosorbent assay and western blotting methods, respectively. CRP levels were also measured in all individuals.

RESULTS

The prevalence of H. pylori infection and CagA status were significantly higher among the patients with AMI than the controls (66 vs. 20% and 75.7 vs. 30%, respectively); the odds ratio was 2.57 (95% confidence interval 1.89-3.49). CRP levels were significantly different in the patients compared with the controls (5.02±1.04 mg/l vs. 2.41±0.9 mg/l, respectively).

CONCLUSION

Our results confirmed that the patients with AMI had a significantly higher prevalence of H. pylori infection and CagA seropositivity than the control population. Infection with H. pylori may influence AMI, which in our findings shows an association between H. pylori seropositivity and AMI through an inflammatory process.

Social determinants of cardiac disease biomarkers: investigating a Swedish male cohort at ages 50 and 70

BACKGROUND

Social status is associated with cardiovascular disease (CVD) prevalence and incidence.

AIMS

to investigate relationships between socioeconomic position (SEP) and common CVD biomarkers including adiponectin not previously investigated in a Swedish-population sample, and to assess if these associations changed with age.

DESIGN

Population-based longitudinal cohort study of men born 1920-24 with clinical measurements, blood samples, questionnaire data, and register-based information on SEP and cause of death.

METHODS

A total of 2322 men attended an investigation at age 50 of which 1221 attended a reinvestigation at age 70. Association between SEP and CVD biomarkers [cholesterol, low-density lipoprotein/high-density lipoprotein (LDL/HDL), apolipoprotein (Apo) ApoB/ApoA1, and adiponectin] were analysed by linear regression (adjusted for age, body mass index, and physical activity). SEP was measured as occupational class and educational level. CVD mortality over 36 years of follow-up was analysed by Cox regression.

RESULTS

At age 50, we found a significant inverse association of education with cholesterol level, LDL/HDL ratio and ApoB/ApoA1 ratio. Cholesterol was also associated with occupational class, statistically significant after adjustment for all covariates. At age 70, no significant associations were found between either measurement of SEP and any of the biomarkers studied. Highest educated men had decreased risk for CVD mortality during follow-up.

CONCLUSIONS

Associations of SEP with cholesterol levels and LDL/HDL ratio that exist at age 50 are no longer apparent in the same group of men at age 70. We found no significant association between SEP and adiponectin levels at age 70.

Increasing socioeconomic inequalities in first acute myocardial infarction in Scotland, 1990-92 and 2000-02

Background

Despite substantial declines, Ischaemic Heart Disease (IHD) remains the largest cause of death in Scotland and mortality rates are among the worst in Europe. There is evidence of strong, persisting regional and socioeconomic inequalities in IHD mortality, with the majority of such deaths being due to Acute Myocardial Infarction (AMI). We examine the changes in socioeconomic and geographic inequalities in first AMI events in Scotland and their interactions with age and gender.

Methods

We used linked hospital discharge and death records covering the Scottish Population (5.1 million). Risk ratios (RR) of AMI incidence by area deprivation and age for men and women were estimated using multilevel Poisson modelling. Directly standardised rates were presented within these stratifications.

Results

During 1990–92 74,213 people had a first AMI event and 56,995 in 2000–02. Adjusting for area deprivation accounted for 59% of the geographic variability in AMI incidence rates in 1990–92 and 33% in 2000–02. Geographic inequalities in male incidence reduced; RR for smaller areas (comparing area on 97.5th centile to 2.5th) reduced from 1.42 to 1.19. This was not true for women; RR increased from 1.45 to 1.59. The socioeconomic gradient in AMI incidence increased over time (p-value < 0.001) but this varied by age and gender. The gradient across deprivation categories for male incidence in 1990–92 was most pronounced at younger ages; RR of AMI in the most deprived areas compared to the least was 2.6 (95% CI: 1.6–4.3) for those aged 45–59 years and 1.6 (1.1–2.5) at 60–74 years. This association was also evident in women with even stronger socioeconomic gradients; RRs for these age groups were 4.4 (3.4–5.5), and 1.9 (1.7–2.2). Inequalities increased by 2000–02 for both sexes; RR for men aged 45–59 years was 3.3 (3.0–3.6) and for women was 5.6 (4.1–7.7)

Conclusion

Relative socioeconomic inequalities in AMI incidence have increased and gradients are steepest in young women. The geographical patterning of AMI incidence cannot be fully explained by socioeconomic deprivation. The reduction of inequalities in AMI incidence is key to reducing overall inequalities in mortality and must be a priority if Scotland is to achieve its health potential.