Lucy Lennon

Low grade inflammation and coronary heart disease : prospective study and updated meta-analyses

Abstract Objective: To assess associations between baseline values of four different circulating markers of inflammation and future risk of coronary heart disease, potential triggers of systemic inflammation (such as persistent infection), and other markers of inflammation. Design: Nested case-control comparisons in a prospective, population based cohort. Setting: General practices in 18 towns in Britain. Participants: 506 men who died from coronary heart disease or had a non-fatal myocardial infarction and 1025 men who remained free of such disease until 1996 selected from 5661 men aged 40–59 years who provided blood samples in 1978-1980. Main outcome measures: Plasma concentrations of C reactive protein, serum amyloid A protein, and serum albumin and leucocyte count. Information on fatal and non-fatal coronary heart disease was obtained from medical records and death certificates. Results: Compared with men in the bottom third of baseline measurements of C reactive protein, men in the top third had an odds ratio for coronary heart disease of 2.13 (95% confidence interval 1.38 to 3.28) after age, town, smoking, vascular risk factors, and indicators of socioeconomic status were adjusted for. Similar adjusted odds ratios were 1.65 (1.07 to 2.55) for serum amyloid A protein; 1.12 (0.71 to 1.77) for leucocyte count; and 0.67 (0.43 to 1.04) for albumin. No strong associations were observed of these factors with Helicobacter pylori seropositivity, Chlamydia pneumoniae IgG titres, or plasma total homocysteine concentrations. Baseline values of the acute phase reactants were significantly associated with one another (P<0.0001), although the association between low serum albumin concentration and leucocyte count was weaker (P=0.08). Conclusion: In the context of results from other relevant studies these findings suggest that some inflammatory processes, unrelated to the chronic infections studied here, are likely to be involved in coronary heart disease.

Long-Term Interleukin-6 Levels and Subsequent Risk of Coronary Heart Disease: Two New Prospective Studies and a Systematic Review

Background The relevance to coronary heart disease (CHD) of cytokines that govern inflammatory cascades, such as interleukin-6 (IL-6), may be underestimated because such mediators are short acting and prone to fluctuations. We evaluated associations of long-term circulating IL-6 levels with CHD risk (defined as nonfatal myocardial infarction [MI] or fatal CHD) in two population-based cohorts, involving serial measurements to enable correction for within-person variability. We updated a systematic review to put the new findings in context. Methods and Findings Measurements were made in samples obtained at baseline from 2,138 patients who had a first-ever nonfatal MI or died of CHD during follow-up, and from 4,267 controls in two cohorts comprising 24,230 participants. Correction for within-person variability was made using data from repeat measurements taken several years apart in several hundred participants. The year-to-year variability of IL-6 values within individuals was relatively high (regression dilution ratios of 0.41, 95% confidence interval [CI] 0.28–0.53, over 4 y, and 0.35, 95% CI 0.23–0.48, over 12 y). Ignoring this variability, we found an odds ratio for CHD, adjusted for several established risk factors, of 1.46 (95% CI 1.29–1.65) per 2 standard deviation (SD) increase of baseline IL-6 values, similar to that for baseline C-reactive protein. After correction for within-person variability, the odds ratio for CHD was 2.14 (95% CI 1.45–3.15) with long-term average (“usual”) IL-6, similar to those for some established risk factors. Increasing IL-6 levels were associated with progressively increasing CHD risk. An updated systematic review of electronic databases and other sources identified 15 relevant previous population-based prospective studies of IL-6 and clinical coronary outcomes (i.e., MI or coronary death). Including the two current studies, the 17 available prospective studies gave a combined odds ratio of 1.61 (95% CI 1.42–1.83) per 2 SD increase in baseline IL-6 (corresponding to an odds ratio of 3.34 [95% CI 2.45–4.56] per 2 SD increase in usual [long-term average] IL-6 levels). Conclusions Long-term IL-6 levels are associated with CHD risk about as strongly as are some major established risk factors, but causality remains uncertain. These findings highlight the potential relevance of IL-6–mediated pathways to CHD.

Physical activity and hemostatic and inflammatory variables in elderly men

Background—Physical activity is associated with lower risk of cardiovascular disease, but the mechanisms are uncertain. Hemostatic and inflammatory markers have been linked with risk of cardiovascular disease. We therefore examined the relationship between physical activity and hemostatic and inflammatory variables. Methods and Results—In 1998 to 2000, 20 years after the initial screening of 7735 men 40 to 59 years old from general practices in 24 British towns, 4252 subjects (77% of available survivors, now 60 to 79 old) attended for reexamination. A fasting blood sample was available in 4088 men. All men on warfarin (n=134) and men with incomplete data on physical activity (n=144) were excluded, leaving 3810 men for analysis. Physical activity showed a significant and inverse dose-response relationship with fibrinogen, plasma and blood viscosity, platelet count, coagulation factors VIII and IX, von Willebrand factor, fibrin d-dimer, tissue plasminogen activator antigen, C-reactive protein, and white cell count, even after adjustment for possible confounders. The effects were similar in men with and without prevalent cardiovascular disease. No relationship was seen with activated partial thromboplastin time, activated protein C resistance, hematocrit, or factor VII. An examination of changes in physical activity between baseline and 20 years later showed that inactive men who took up at least light physical activity had levels of blood variables approaching those who remained at least lightly active. Those who became inactive showed levels more similar to those who remained inactive. Conclusions—These data suggest that the benefit of physical activity on cardiovascular disease may be at least partly a result of effects on hemostasis and inflammation.

Can metabolic syndrome usefully predict cardiovascular disease and diabetes? Outcome data from two prospective studies.

BACKGROUND Clinical use of criteria for metabolic syndrome to simultaneously predict risk of cardiovascular disease and diabetes remains uncertain. We investigated to what extent metabolic syndrome and its individual components were related to risk for these two diseases in elderly populations. METHODS We related metabolic syndrome (defined on the basis of criteria from the Third Report of the National Cholesterol Education Program) and its five individual components to the risk of events of incident cardiovascular disease and type 2 diabetes in 4812 non-diabetic individuals aged 70-82 years from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). We corroborated these data in a second prospective study (the British Regional Heart Study [BRHS]) of 2737 non-diabetic men aged 60-79 years. FINDINGS In PROSPER, 772 cases of incident cardiovascular disease and 287 of diabetes occurred over 3.2 years. Metabolic syndrome was not associated with increased risk of cardiovascular disease in those without baseline disease (hazard ratio 1.07 [95% CI 0.86-1.32]) but was associated with increased risk of diabetes (4.41 [3.33-5.84]) as was each of its components, particularly fasting glucose (18.4 [13.9-24.5]). Results were similar in participants with existing cardiovascular disease. In BRHS, 440 cases of incident cardiovascular disease and 105 of diabetes occurred over 7 years. Metabolic syndrome was modestly associated with incident cardiovascular disease (relative risk 1.27 [1.04-1.56]) despite strong association with diabetes (7.47 [4.90-11.46]). In both studies, body-mass index or waist circumference, triglyceride, and glucose cutoff points were not associated with risk of cardiovascular disease, but all five components were associated with risk of new-onset diabetes. INTERPRETATION Metabolic syndrome and its components are associated with type 2 diabetes but have weak or no association with vascular risk in elderly populations, suggesting that attempts to define criteria that simultaneously predict risk for both cardiovascular disease and diabetes are unhelpful. Clinical focus should remain on establishing optimum risk algorithms for each disease.

Soluble adhesion molecules and prediction of coronary heart disease: a prospective study and meta-analysis

BACKGROUND Previous studies have suggested that circulating concentrations of soluble adhesion molecules are useful predictors of risk of coronary heart disease (CHD). Larger studies are needed, however, to test this hypothesis. METHODS We measured serum concentrations of four soluble cell adhesion molecules (intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1], E-selectin, and P-selectin) in the stored baseline serum samples of 643 men with coronary heart disease and 1278 controls nested in a prospective sutdy of 5661 men who were monitored for 16 years. We also did a meta-analysis of previous relevant studies to place our findings in context. RESULTS Concentrations of soluble adhesion molecules were significantly associated with one another, with other markers of inflammation, and with some classic coronary risk factors. For ICAM-1, the odds ratio for CHD was 1.68 (95% CI 1.32-2.14) in a comparison of men in the top third with those in the bottom third of baseline measurements after adjustments for age and town. This decreased to 1.11 (0.75-1.64) after adjustment for some classic coronary risk factors and indicators of socioeconomic status. For the three other cell adhesion molecules, the odds ratios for CHD, first adjusted for age and town only, and then additionally adjusted for other risk factors, were: VCAM-1: 1.26 (0.99-1.61) and 0.96 (0.66-1.40); E-selectin: 1.27 (1.00-1.61) and 1.13 (0.78-1.62); and P-selectin: 1.23 (0.96-1.56) and 1.20 (0.81-1.76). INTERPRETATION The measurement of these adhesion molecules is unlikely to add much predictive information to that provided by more established risk factors.

Fibrin D-dimer and coronary heart disease - prospective study and meta-analysis

Background—It is unknown whether modest increases of fibrin D-dimer, a circulating marker of fibrin turnover, are relevant to coronary heart disease (CHD) in the general population. Methods and Results—We measured serum concentrations of D-dimer antigen in the stored baseline blood samples of 630 CHD cases and 1269 controls “nested” in a prospective cohort of 5661 men who were monitored for 16 years, and we conducted a meta-analysis of previous relevant studies to place our findings in context. In a comparison of men in the top third compared with those in the bottom third of baseline fibrin D-dimer values (tertile cutoffs, >94 versus <49 ng/mL), the odds ratio for CHD was 1.67 (95% CI, 1.31 to 2.13;P <0.0001) after adjustments for age and town. The odds ratio increased slightly after further adjustment for smoking, other classic risk factors, and indicators of socioeconomic status (1.79; 95% CI, 1.36 to 2.36). Strong correlations were observed of fibrin D-dimer values with circulating concentrations of C-reactive protein and serum amyloid A protein but not with smoking, blood lipids, blood pressure, and other risk factors. Conclusion—Although there may be an association between circulating D-dimer values and CHD, further studies are needed to determine the extent to which this is causal.

Chlamydia pneumoniae IgG titres and coronary heart disease: prospective study and meta-analysis.

Abstract Objective: To examine the association between coronary heart disease and serum markers of chronic Chlamydia pneumoniae infection. Design: “Nested” case-control analysis in a prospective cohort study and an updated meta-analysis of previous relevant studies. Setting: General practices in 18 towns in Britain. Participants: Of the 5661 men aged 40–59 who provided blood samples during 1978-80, 496 men who died from coronary heart disease or had non-fatal myocardial infarction and 989 men who had not developed coronary heart disease by 1996 were included. Main outcome measures: IgG serum antibodies to C pneumoniae in baseline samples; details of fatal and non-fatal coronary heart disease from medical records and death certificates. Results: 200 (40%) of the 496 men with coronary heart disease were in the top third of C pneumoniae titres compared with 329 (33%) of the 989 controls. The corresponding odds ratio for coronary heart disease was 1.66 (95% confidence interval 1.25 to 2.21), which fell to 1.22 (0.82 to 1.82) after adjustment for smoking and indicators of socioeconomic status. No strong associations were observed between C pneumoniae IgG titres and blood lipid concentrations, blood pressure, or plasma homocysteine concentration. In aggregate, the present study and 14 other prospective studies of C pneumoniae IgG titres included 3169 cases, yielding a combined odds ratio of 1.15 (0.97 to 1.36), with no significant heterogeneity among the separate studies (χ2=10.5, df=14; P>0.1). Conclusion: This study, together with a meta-analysis of previous prospective studies, reliably excludes the existence of any strong association between C pneumoniae IgG titres and incident coronary heart disease. Further studies are required, however, to confirm or refute any modest association that may exist, particularly at younger ages.

How much of the recent decline in the incidence of myocardial infarction in British men can be explained by changes in cardiovascular risk factors? Evidence from a prospective population-based study.

Background— The incidence of myocardial infarction (MI) in Britain has fallen markedly in recent years. Few studies have investigated the extent to which this decline can be explained by concurrent changes in major cardiovascular risk factors. Methods and Results— The British Regional Heart Study examined changes in cardiovascular risk factors and MI incidence over 25 years from 1978 in a cohort of 7735 men. During this time, the age-adjusted hazard of MI decreased by 3.8% (95% confidence interval 2.6% to 5.0%) per annum, which corresponds to a 62% decline over the 25 years. At the same time, after adjustment for age, cigarette smoking prevalence, mean systolic blood pressure, and mean non–high-density lipoprotein (HDL) cholesterol decreased, whereas mean HDL cholesterol, mean body mass index, and physical activity levels rose. No significant change occurred in alcohol consumption. The fall in cigarette smoking explained the greatest part of the decline in MI incidence (23%), followed by changes in blood pressure (13%), HDL cholesterol (12%), and non-HDL cholesterol (10%). In combination, 46% (approximate 95% confidence interval 23% to 164%) of the decline in MI could be explained by these risk factor changes. Physical activity and alcohol consumption had little influence, whereas the increase in body mass index would have produced a rise in MI risk. Conclusions— Modest favorable changes in the major cardiovascular risk factors appear to have contributed to considerable reductions in MI incidence. This highlights the potential value of population-wide measures to reduce exposure to these risk factors in the prevention of coronary heart disease.

Validity of a self-reported history of doctor-diagnosed angina.

The objective of this study was to assess the validity of a self-reported history of doctor-diagnosed angina in population-based studies in men. Subjects were 5789 men from the British Regional Heart Study who reported being without an angina diagnosis at entry (1978-1980) and were alive at the end of 1992, aged 52 to 75 years. In 1992, subjects were asked in a self-administered questionnaire if they recalled ever having had a doctor diagnosis of angina. Self-report of diagnosed angina was compared with general practice (GP) record of angina obtained from reviews of medical records from study entry to the end of 1992. Men were followed for a further 3 years from 1992 for major ischemic heart disease events. The prevalence of diagnosed angina in 1992 was 10.1% according to self-reported history and 8.9% according to GP record review. There was substantial agreement between the two sources of information: 80% of men with a GP record of angina reported their diagnosis, and 70% of men who reported an angina diagnosis had confirmation of this from the record review. When all ischemic heart disease (angina or myocardial infarction) was considered, agreement was higher. Genuine angina was likely in many of the 177 men who had self-reported angina not confirmed by the GP record review: 78 had an ischemic heart disease history (myocardial infarction or coronary revascularization) identified by the review, and 31 had a GP record of angina after 1992. Angina symptoms, nitrate use, cardiological investigation, and surgical intervention for angina compared between agreement groups showed a very consistent pattern. All these indicators of angina were most common in men with both self-report and GP record of angina, least common in men with neither self-report nor GP record of angina, but had a substantially higher prevalence in men with self-reported angina only than in those with GP-recorded angina only. After 3 years follow-up from 1992, 9.5% of men with both self-report and GP record of angina, and 11.3% of men with self-reported angina only had experienced a new major ischemic heart disease event; compared to 5.7% of men with a GP record of angina only and 2.7% of those without angina by either criteria. This pattern of risk remained similar after adjustment for age and previous myocardial infarction. These results suggest that self-reported history of a doctor diagnosis of angina is a valid measure of diagnosed angina in population-based studies in men.

Sarcopenic Obesity and Risk of Cardiovascular Disease and Mortality: A Population-Based Cohort Study of Older Men

To examine associations between sarcopenia, obesity, and sarcopenic obesity and risk of cardiovascular disease (CVD) and all‐cause mortality in older men.