Relation of markers of inflammation (C-reactive protein, white blood cell count, and lipoprotein-associated phospholipase A2) to the ankle brachial index

The association between C-reactive protein and common blood tests in apparently healthy individuals undergoing a routine health examination

BACKGROUND

C-reactive protein (CRP) is considered a marker of inflammation. We sought to evaluate the association between CRP level and commonly use blood tests in apparently healthy population.

METHODS

A cross-sectional study of all visits in a routine health examination center between 1/2002 and 7/2018. CRP, complete blood count and chemistry blood panel were evaluated in each visit. Visits of individuals who had CRP above the 99th percentile or use statins were excluded. Correlation between CRP and blood tests was evaluated in the whole cohort as well as in sub-populations.

RESULTS

Blood parameters of 33,261 visits were included. Moderate positive correlation between CRP and white blood cells count (r = 0.269), neutrophils count (r = 0.275), triglycerides (r = 0.275), alkaline phosphatase (r = 0.221) and gamma glutamyl transpeptidase (r = 0.220) was evaluated. Correlation with triglycerides was stronger in female then in males (r = 0.38 vs. 0.25). Uric acid was positively correlated in females and males. In participants under 30 years, inverse correlation with hemoglobin, creatinine and albumin levels and positive correlation with cholesterol were documented.

CONCLUSION

Significant moderate association between CRP and several blood tests was evaluated in apparently healthy population. This information should be used for further studies of the relationship between inflammation and biological processes.

Lipoprotein-Associated Phospholipase A2 and Incident Peripheral Arterial Disease in Older Adults: The Cardiovascular Health Study

OBJECTIVE

Although prior studies report a relationship between elevated lipoprotein-associated phospholipase A2 (Lp-PLA2) and incident cardiovascular disease, the prospective association of Lp-PLA2 with incident peripheral arterial disease (PAD) has not been studied. We investigated the association between Lp-PLA2 mass and activity and the risk of developing clinical PAD and low ankle-brachial index (ABI).

APPROACH AND RESULTS

Among Cardiovascular Health Study participants, a population-based cohort of 5888 adults aged ≥65 years enrolled in 1989 to 1990, Lp-PLA2 mass and activity were measured in 4537 individuals without baseline PAD. Clinical PAD, defined as leg artery revascularization or diagnosed claudication, was ascertained through 2011. Incident low ABI, defined as ABI <0.9 and decline of ≥0.15, was assessed among 3537 individuals who had an ABI >0.9 at baseline and a second ABI measurement 3 or 6 years later. Analyses were adjusted for demographics, cholesterol, smoking, comorbidities, and C-reactive protein. Each standard deviation increment in Lp-PLA2 mass (117 ng/mL) was associated with a higher risk of developing clinical PAD (hazard ratio 1.28; 95% confidence interval 1.13, 1.45) and incident low ABI (odds ratio 1.16; 95% confidence interval 1.00, 1.33). Results per standard deviation increment in Lp-PLA2 activity (13 nmol/min per mL) were similar for clinical PAD (hazard ratio 1.24; 95% confidence interval 1.07, 1.44) and low ABI (odds ratio 1.28; 95% confidence interval 1.09, 1.50).

CONCLUSIONS

Higher Lp-PLA2 mass and activity were associated with development of both incident clinical PAD and low ABI. Future studies are needed to determine whether pharmacological inhibition of Lp-PLA2 reduces the incidence of PAD.

sRAGE, inflammation, and risk of atrial fibrillation: results from the Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

Advanced glycation end products (AGEs) may cause inflammation by binding to their cellular receptors (RAGE). Soluble RAGE (sRAGE) acts as a decoy receptor for AGEs and may prevent inflammation. Chronic low-grade inflammation is a risk factor for cardiovascular disease, including atrial fibrillation (AF).

METHODS

We studied 1,068 participants in a subsample of the Atherosclerosis Risk in Communities (ARIC) Study who had baseline measurements of sRAGE (mean age 56, 60% female, 21% Black). Inflammation was assessed using measurements of high sensitivity C-reactive protein (hsCRP), fibrinogen, gamma-glutamyl transferase (GGT) and white blood cell (WBC) count. AF events were identified using ECG data, hospitalization discharge codes, and linkage to the National Death Index.

RESULTS

Compared to the highest quartile (>1272.4 pg/mL), the lowest quartile of sRAGE (<714 pg/mL) was associated with higher baseline levels of inflammation (hsCRP ≥3 mg/L: OR=2.21 [95% CI 1.41-3.49], fibrinogen ≥400 mg/dL: OR=4.31 [95% CI 1.50-12.41], GGT ≥36 U/L in women and ≥61 U/L in men: OR=5.22 [95% CI 2.66-10.22], WBC >6.2×10⁹/L: OR=2.38 [95% CI 1.52-3.72]). sRAGE was not prospectively associated with 6-year change in inflammatory markers (hsCRP or GGT). There was no significant association of sRAGE and risk of AF (HR 1.49 [95% CI: 0.80-2.78] for the 1st vs. 4th quartile of sRAGE).

CONCLUSIONS

sRAGE was strongly inversely associated with markers of inflammation at baseline, but not prospectively. sRAGE was not significantly associated with incident AF. This supports a role for sRAGE in attenuating current inflammation, but it remains unclear whether sRAGE plays a role in the development of AF.

Study of risk factors associated with peripheral arteriopathy in Japanese-Brazilians from Bauru (SP)

BACKGROUND

Cardiovascular diseases are the major cause of morbidity and mortality in developed and emerging countries. Their main etiology, atherosclerosis, is a disseminated disease that affects the coronary, cerebral and peripheral territories. The peripheral arterial disease (PAD), as well as its consequences, indicates the involvement of the coronary territory. Therefore, its better understanding enables proper treatment, delaying local and long-term complications, reducing the cost to the health system.

OBJECTIVE

This study estimates the percentage of PAD in Japanese-Brazilians from Bauru (SP), recognized by the high prevalence of metabolic disorders such as hypertension (43%), diabetes mellitus (33%) and hypercholesterolemia (60%), and examines the association with risk biomarkers.

METHODS

This cross-sectional population study evaluated 1,330 Japanese-Brazilians of both genders aged≥30 who underwent a complete physical examination, anthropometric measurements, laboratory tests and ankle-brachial index (ABI). Participants with ABI≤0.90 were diagnosed as having PAD. After applying the exclusion criteria, 1,038 individuals were part of the analysis. We used Poisson regression to analyze associations with PAD.

RESULTS

The mean age was 56.8 years and the percentage of PAD was 21.1%, equal among the genders. PAD was associated with smoking (PR 2.16 [1.33 to 3.48]) and hypertension (PR 1.56 [1.12-2.22]).

CONCLUSION

The percentage of PAD in Japanese-Brazilians was similar to other populations of adverse cardiometabolic profile (US PARTNERS and POPADAD). The independent association of PAD with smoking and hypertension, but not with other classical risk factors, may depend on the very high frequencies of metabolic disorders in this population.

Not all smokers die young: a model for hidden heterogeneity within the human population

The ability of some individuals to reach extreme old age in the presence of clearly high exposure to damaging factors may signal an innate biological advantage. For this study we used data on 4,655 current and never smokers, ages 50 and above, from NHANES III to examine whether long-lived smokers represent a biologically resilient phenotype that could facilitate our understanding of heterogeneity in the aging process. Using a proportional hazards model, our results showed that while smoking significantly increased mortality in most age groups, it did not increase the mortality risk for those who were age 80 and over at baseline. Additionally when comparing the adjusted means of biomarkers between never and current smokers, we found that long-lived smokers (80+) had similar inflammation, HDL, and lung function levels to never smokers. Given that factors which allow some individuals to withstand smoking may also enable others to cope with everyday biological stressors, the investigation of long-lived smokers may eventually allow us to identify molecular and genetic mechanisms which enable longevity extension.

Preliminary Results of a Prospective Study on Severe Lower Limb Trauma: Analysis of Laboratory Tests as Predictors of Amputation

The decision of either preserving a member or primary amputation (PA) in severe extremity trauma, especially in the presence of fractures, vascular injuries or serious injuries of soft tissues has always been a challenge for the trauma surgeon. The initial assessment with objective criteria like indexes, such as the Mangled Extremity Severity Score (MESS) or the PSI, can aid in the differentiation of members that can be saved or should be amputated primarily. We report on the design and preliminary results of our ongoing prospective study analyzing laboratory test as predictors of amputation in severe lower limb trauma.

Materials and methods

All patients treated in our emergency department with severe lower limb trauma and open fractures (classified as Gustilo III) were included in this study. We collected blood for laboratory test of all patients at admission. All injured limb were photographed for posterior analysis and MESS classification.

Results

From March 15, 2012, to June 10, 2012, n = 20 patients were included in our study. PA was performed in eight (40%) and preserving procedures (PP) in 12 (60%). Mean age was 30 in PP group and 40.5 in PA. Mean systolic pressure at the emergency room was 130 mm Hg in PP and 107 mm Hg in PA. MESS index was calculated for all patients and the means were 5 for the PP group and 8 for the PA group. Laboratory test of the two groups were compared and statistically analyzed. Acidosis, arterial lactate levels and hemoglobin levels at admission had a statistical difference between the two groups: pH = 7.36 PP vs 7.18 PA (p = 0.001); lactate: PP = 25 vs PA = 63 (p < 0.001); hemoglobin: PP = 13.6 vs PA = 7.85 (p = 0.03).

Conclusion

Laboratory results of tests collected during initial assessment of patients with severe lower limb trauma are different between those submitted to PA or a PP.

How to cite this article

Garcia DFV, de Sá RRC, Bernini CO, Rasslan S . Preliminary Results of a Prospective Study on Severe Lower Limb Trauma: Analysis of Laboratory Tests as Predictors of Amputation. Panam J Trauma Critical Care Emerg Surg 2013;2(1):58-61.

A Study of Association of Ankle Brachial Index (ABI) and the Highly Sensitive C - Reactive Protein (hsCRP) in Type 2 Diabetic Patients and in Normal Subjects

BACKGROUND

The Ankle-Brachial Index (ABI) objectively assesses the lower extremity arterial perfusion. A low ABI suggests atherosclerosis and Peripheral Arterial Disease (PAD). PAD is more common in individuals with type2 Diabetes mellitus (Type2 DM). Inflammatory markers are found to be associated with Type2 DM. But the association of the inflammatory markers with the atherosclerotic burden remains poorly defined.

AIMS

To compare the ABI and the hsCRP in the Type 2 DM patients with those in the normal subjects and to study the association of serum hsCRP with ABI in the Type 2 DM patients and in normal subjects.

METHODS

The subjects were 40 Type2 DM and 40 age, sex and BMI matched normal subjects who were aged between 45-60 yrs. The subjects were assigned to two different groups, Group1- the Type2 DM patients and Group2- the healthy controls. The serum hsCRP levels were determined by the turbidimetry method (BIOSYSTEMS) and the ABI values were determined by using the traditional continuous wave (CW) Doppler of NICOLET VERSALAB.

STATISTICAL ANALYSIS

The data was analyzed by using the Student's t test (two tailed; independent) to find the significance of the study parameters between the two groups. Pearson's Correlation was used to find the correlation of serum hsCRP with the ABI in the two groups.

RESULTS

The ABI showed a significantly low value (P=0.035*) and the serum hsCRP showed a trend towards a significant increase (p = 0.069+) in the type2diabetics as compared to those in the normals. There was a significant negative correlation between ABI and hsCRP in the Type 2 DM patients (r=-0.560, p<0.001**). However, such correlation was not observed in the normal subjects.

CONCLUSION

As serum hsCRP is associated with ABI in the type2 DM patients, inflammation may play a role in the pathogenesis of atherosclerosis.

Predicting the Risk of Cardiovascular Disease

Although an atherogenic lipoprotein phenotype has been well recognized as an important predictor of cardiovascular disease, recent studies have demonstrated a number of additional lipid-related markers as emerging biomarkers to identify patients at risk for future coronary heart disease. Among them, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), seems to be a promising candidate that might be added to the clinical armamentarium for improved prediction of cardiovascular disease in the future. Of particular note, Lp-PLA(2) is the only enzyme that cleaves oxidized low-density lipoprotein (oxLDL) in the subendothelial space, with further generation of proinflammatory mediators such as lysophosphatidylcholine (LysoPC) and oxidized fatty acid (oxFA), thereby probably linking two important features of atherogenesis, namely oxidation of LDL and local inflammatory processes within the atherosclerotic plaque. This overview aims to summarize our current knowledge based on observations from recent experimental and clinical studies. Emphasis has been put on potential pathophysiological mechanisms of action and on the clinical relevance of Lp-PLA(2) in a wide variety of clinical settings, including apparently healthy individuals, patients with stable angina or acute coronary syndromes, after myocardial infarction, and with subclinical disease. Although a growing body of evidence from epidemiological and clinical studies suggests that Lp-PLA(2) may represent an independent and clinically relevant long-term risk marker for coronary heart disease and, probably, also for stroke, the role of this enzyme in the setting of the acute coronary syndrome remains to be established.

Variation of lipoprotein associated phospholipase A2 across demographic characteristics and cardiovascular risk factors: a systematic review of the literature

BACKGROUND

Lipoprotein association phospholipase A2 (Lp-PLA(2)), an enzyme which has been found in atherosclerotic plaque is currently under investigation in large Phase III clinical trials of vascular disease prevention. We assessed in a variety of different population settings variation of Lp-PLA(2) mass and activity across gender, ethnicity, diabetes, kidney disease and metabolic syndrome. We also assessed correlations with measures of circulating lipids, systemic inflammation and adiposity.

METHODS

Systematic review of studies measuring Lp-PLA(2) and at least one of the relevant characteristics in >50 participants.

RESULTS

We identified a total of 77 studies involving 102,499 participants meeting the inclusion criteria. Lp-PLA(2) mass and activity were consistently approximately 10% higher in males than females and 15% higher in Caucasians than African Americans or Hispanics. There were no clear associations of Lp-PLA(2) mass or activity with type II diabetes, markers of systemic inflammation (C-reactive protein, fibrinogen) or with body mass index. Correlations of Lp-PLA(2) mass or activity with low density lipoprotein cholesterol and apolipoprotein B were moderate and positive, whilst correlations with high density lipoprotein cholesterol were negative and moderate to weak. There was no clear differences in associations with any of the above characteristics in groups defined based upon prevalent cardiovascular disease or its risk factors.

CONCLUSIONS

Despite considerable variability in absolute levels of Lp-PLA(2) across studies, the variability of Lp-PLA(2) across gender, ethnicity, and levels of circulating lipids and markers of systemic inflammation are more consistent and appear not to vary importantly across categories defined by CVD or its risk factors.

Serum N-terminal pro-B-type natriuretic peptide levels are associated with functional capacity in patients with peripheral arterial disease

We hypothesized that higher serum levels of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) are associated with lower functional capacity in patients with peripheral arterial disease ([PAD] n = 481, mean age 67, 68% men). Functional capacity was quantified as distance walked on a treadmill for 5 minutes. Patients were divided into 3 groups according to the distance walked: >144 yards (group 1, n = 254); 60 to 144 yards (group 2, n = 80); <60 yards or did not walk (group 3, n = 147). The association between NT-pro-BNP levels and the ordinal 3-level walking distance was assessed using multivariable ordinal logistic regression analyses that adjusted for several possible confounding variables. Higher levels of NT-pro-BNP were associated with a lower ordinal walking category independent of possible confounders (odds ratio [OR] 1.51, 95% confidence interval [CI] 1.28-1.77; P < .001). In conclusion, higher levels of NT-pro-BNP are independently associated with lower functional capacity in patients with PAD and may be a marker of hemodynamic stress in these patients.

Age as a modulator of inflammatory cardiovascular risk factors

OBJECTIVE

Levels of acute phase reactants are affected by age. The extent to which cardiovascular risk associated with aging is due to an increase in the inflammatory burden is not known. We assessed the relationship with age of inflammatory markers, representing (1) systemic (C-reactive protein, fibrinogen, and serum amyloid-A) and (2) vascular (lipoprotein-associated phospholipase A(2) and pentraxin-3) inflammation.

METHODS AND RESULTS

We determined lipoprotein-associated phospholipase A(2) mass and activity, C-reactive protein, fibrinogen, serum amyloid-A, and pentraxin-3 levels and other cardiovascular disease risk factors in 336 whites and 224 African Americans. Levels of systemic inflammatory markers increased significantly with age in both ethnic groups (P<0.05 for all), whereas trend patterns of vascular inflammatory markers did not change significantly with age for either group. In multivariate regression models adjusting for confounding variables, age remained independently associated with a composite Z score for systemic but not vascular inflammation (β=0.250, P<0.001, and β=0.276, P<0.001, for whites and African Americans, respectively).

CONCLUSIONS

We report an increase in the systemic but not vascular inflammatory burden with age. Levels of both categories of inflammatory markers with age were similar across ethnicity after adjustment for confounders. Our results underscore the importance of age in evaluating inflammatory markers to assess cardiovascular risk.

Ethnic differences in ankle brachial index are present in middle-aged individuals without peripheral arterial disease

INTRODUCTION

To better understand the basis for previously reported ethnic differences in ankle brachial index (ABI), we investigated whether these differences were present in individuals without known peripheral arterial disease (PAD).

METHODS

We used data from National Health and Nutrition Examination surveys (NHANES 1999-2004) to determine whether ethnic differences were present in respondents without PAD (1 ≤ ABI ≤ 1.3). We assessed whether ethnicity was an independent predictor of ABI and ankle systolic blood pressure (SBP) in linear regression models that adjusted for conventional and novel cardiovascular risk factors. To minimize effects of atherosclerosis on ABI, we studied adults aged ≤ 60 years, and also repeated our analyses in a subset aged ≤ 50 years that did not have risk factors for PAD.

RESULTS

3348 participants aged ≤ 60 years were included in the study. Mean ABI was 1.11 in non-Hispanic Blacks (NHB) and 1.13 in non-Hispanic Whites (NHW) (P < 0.0001). In multivariable linear regression analysis that adjusted for age, gender, ethnicity, smoking, height, diabetes, brachial SBP, dyslipidemia, diabetes, renal function, concurrent cardiovascular disease, and plasma levels of homocysteine, fibrinogen and C-reactive protein, NHB had lower ABI than NHW (β = -0.03 ± 0.004, P < 0.00001). Although, NHBs had higher ankle SBP than NHWs (by 5.4 mm Hg), NHBs had a lower mean ankle SBP (β = -3.663 mm Hg ± 0.500, P < 0.0001) after adjusting for clinical covariates, including brachial SBP, in multivariable analysis.

CONCLUSION

Ethnic differences in ABI are present in middle-aged adults at low risk for peripheral atherosclerosis.

Do Novel Risk Biomarkers Reflect the Severity of Peripheral Arterial Disease?

The association between novel atherosclerotic risk biomarkers and severity of peripheral arterial disease (PAD) was assessed. Patients (n = 133) with PAD were recruited. Established risk biomarkers including low- and high-density cholesterol, triglycerides, and blood pressure were measured. Novel risk biomarkers including plasma C-reactive protein, von Willebrand factor (vWF), interleukin 6, red cell folate (RCF), vitamin B12, total homocysteine (tHcy), and Hcy genotypes were also determined. The severity of PAD was evaluated, using ankle—brachial pressure index (ABPI), brachial—knee, and brachial—ankle pulse wave velocity (bk- and ba-PWV). Plasma tHcy and systolic blood pressure had a positive independent correlation with bk-PWV (β = +0.56, P = .02 and β = +0.38, P < .001, respectively). Red cell folate had an independent inverse correlation with bk-PWV (β = —0.01, P = .01). Systolic blood pressure showed an independent positive correlation with ba-PWV only after adjustment for other risk biomarkers (β = +0.1, P = .04). Novel markers, plasma tHcy, and RCF levels correlated with the severity of PAD.

Novel markers of peripheral arterial disease

Peripheral arterial disease (PAD), a relatively common manifestation of atherosclerotic vascular disease, is associated with significant morbidity and mortality. Although conventional risk factors contribute to the onset and progression of PAD, the role of 'novel' biomarkers in pathways of inflammation, thrombosis, lipoprotein metabolism, and oxidative stress in determining susceptibility to PAD is being increasingly recognized. Validation of novel risk factors for PAD may allow earlier detection, an improved understanding of disease etiology and progression, and the development of new therapies. In this review, we discuss available evidence for associations between novel circulating markers and several aspects of PAD including disease susceptibility, progression, functional limitation, and adverse outcomes.

White blood cell count predicts all-cause mortality in patients with suspected peripheral arterial disease

OBJECTIVE

We investigated whether markers of inflammation-white blood cell (WBC) count, C-reactive protein (CRP), and lipoprotein-associated phospholipase A2-are associated with mortality in patients referred for noninvasive lower-extremity arterial evaluation.

METHODS

Participants (n = 242, mean age 68 years, 54% men) were followed for a median of 71 months. Ankle-brachial index (ABI), WBC count, plasma CRP, and lipoprotein-associated phospholipase A2 were measured at the start of the study. Factors associated with all-cause mortality were identified using Cox proportional hazards.

RESULTS

During the follow-up period, 56 patients (25%) died. Factors associated with higher mortality were greater age, history of coronary artery disease/cerebrovascular disease, lower ABI, higher serum creatinine, and higher WBC count/plasma CRP. In stepwise multivariable regression analysis, ABI, serum creatinine, WBC count, and CRP were associated significantly with mortality. Patients in the top tertile of WBC count and CRP level had a relative risk of mortality of 3.37 (confidence interval [CI], 1.56-7.27) and 2.12 (CI, 0.97-4.62), respectively. However, only the WBC count contributed incrementally to prediction of mortality. Inferences were similar when analyses were limited to patients with peripheral arterial disease (ABI<0.9, n = 114).

CONCLUSION

WBC count, but not plasma CRP level, provides incremental information about the risk of death in patients referred for lower-extremity arterial evaluation and in the subset of these patients with peripheral arterial disease.

Effects of G994T in the Lp-PLA2 gene on the plasma oxidized LDL level and carotid intima-media thickness in Japanese: the Shimane study

BACKGROUND

A single-nucleotide polymorphism (SNP), G994T, in the lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) gene is known to have a potent influence on the activity of the enzyme. As this enzyme hydrolyzes oxidized low-density lipoprotein (oxLDL), which is an important player in atherogenesis, the present study evaluated effects of the G994T genotype on the oxLDL level as well as on intima media thickness (IMT) in vivo.

METHODS

Participants of a health examination (1,307 in total) were recruited from two rural communities in Shimane, Japan. Genotyping was performed by an allele-specific PCR and the TaqMan method. The oxLDL level was determined by an enzyme immunoassay.

RESULTS

The minor allele (994T) frequency (0.19) in the studied populations was consistent with previous reports on Japanese. The 994T allele increased the plasma oxLDL/LDL ratio in a recessive manner, whereas 994T had a codominant effect on the Lp-PLA(2) activity. A multivariate analysis revealed that age and the G994T genotype had independent effects on the oxLDL/LDL level. By contrast, the G994T genotype was not associated with IMT. All of these results were reproducible in the two independent populations studied.

CONCLUSIONS

G994T influenced plasma LDL oxidation. Further studies on the effect of this polymorphism in cardiovascular diseases are warranted.

Association of novel risk factors with the ankle brachial index in African American and non-Hispanic white populations

OBJECTIVES

To investigate whether novel risk factors, including C-reactive protein (CRP), fibrinogen, lipoprotein(a) [Lp(a)], and homocysteine levels, are associated with the ankle brachial index (ABI) in African American and non-Hispanic white populations and whether novel risk factors account for ethnic differences in peripheral arterial disease (PAD).

PARTICIPANTS AND METHODS

Between December 2000 and October 2004, original participants in the Genetic Epidemiology Network of Arteriopathy study returned for a second study visit to undergo measurement of risk factors and ABI. The CRP, Lp(a), and homocysteine levels were log transformed to reduce skewness. Multivariable regression analyses were used to assess whether a novel risk factor was associated with ABI after adjustment for conventional risk factors and whether ethnicity was associated with PAD (ABI, <or=0.95) after adjustment for conventional and novel risk factors.

RESULTS

Of 2229 study participants, the ABI was determined in 1395 African American participants (mean +/- SD age, 63 +/- 9 years; 71% women) and 834 white participants (mean +/- SD age, 58 +/- 9 years; 62% women) who belonged to hypertensive sibships. The mean ABI was lower in African American than in white individuals (0.99 +/- 0.1 vs 1.13 +/- 0.1; P < .001). In both ethnic groups, higher levels of CRP, fibrinogen, and homocysteine were each associated with a lower ABI after adjustment for conventional risk factors. In African American participants, the Lp(a) level was also significantly associated with the ABI. African American ethnicity was associated with the presence of PAD after adjustment for conventional risk factors (men: odds ratio [OR], 3.04; 95% confidence interval [CI], 1.80-5.15; women: OR, 2.82; 95% CI, 1.85-4.29), but the risk was significantly attenuated after additional adjustment for novel risk factors (men: OR, 2.11; 95% CI, 1.21-3.70; women: OR, 1.98; 95% CI, 1.26-3.11).

CONCLUSION

Novel risk factors are associated with interindividual variation in ABI in African American and non-Hispanic white populations and partly account for the increased risk of PAD associated with African American ethnicity.

Lipoprotein-associated phospholipase A2: Pathogenic mechanisms and clinical utility for predicting cardiovascular events

Lipoprotein-associated phospholipase A(2 )(Lp-PLA(2)), a member of the phospholipase superfamily, circulates primarily bound to low-density lipoprotein and has been associated with cardiovascular disease risk in epidemiologic studies. However, it has not been established whether Lp-PLA(2) is a risk marker or a risk factor. Identification of individuals with elevated Lp-PLA(2) may improve risk assessment, and Lp-PLA(2) may also provide an additional target of therapy. Statin therapy has been shown to reduce Lp-PLA(2), and selective inhibitors of Lp-PLA(2) are under development. Additional research is needed to further determine the role of Lp-PLA(2) in atherogenesis and atherothrombotic events.

Markers of vascular inflammation are associated with the extent of atherosclerosis assessed as angiographic score and treadmill walking distances in patients with peripheral arterial occlusive disease

The importance of inflammation in atherosclerosis is well established in cardiovascular disease. However, limited data exist on the relationship between vascular inflammation and the severity of peripheral arterial occlusive disease (PAD). We investigated the relationship between biochemical markers of vascular inflammation and the diagnostic measures of PAD: ankle-brachial pressure index (ABI), maximum treadmill walking distance and angiographic score. In 127 patients (mean age 66 years; 64% males) with angiographically verified PAD, fasting blood samples were drawn for determination of selected soluble cell adhesion molecules, cytokines and chemokines. Tumor necrosis factor-alpha (TNFalpha), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and CD40 ligand (CD40L) were all significantly correlated with the angiographic score (p < 0.05 for all). After adjustment for relevant co-variates, MCP-1 and CD40L remained statistically significant (p < 0.01 for both). IL-6 was, independent of other risk factors, inversely correlated with the maximum treadmill walking distance (p < 0.01). Our cross-sectional study in PAD patients showed that the vascular inflammatory markers MCP-1, CD40L and IL-6 were significantly associated with the extent of atherosclerosis, assessed by angiographic score and maximum treadmill walking distance. These findings indicate that vascular inflammation is implicated in PAD, which might be of importance in future diagnosis and treatment of the disease.

Inflammation and Chlamydia pneumoniae Infection Correlate with the Severity of Peripheral Arterial Disease

BACKGROUND

Our aim was to investigate the association of inflammation and Chlamydia pneumoniae infection with the presence and severity of peripheral arterial disease.

METHODS

Twenty-eight patients whose initial claudication distance (ICD) in the traditional constant-load treadmill test was <200 m, underwent femoral endarterectomy as part of their interventional treatment (group A). Group B consisted of 23 patients whose ICD was >200 m and were put on medication and a daily exercise program. The control group consisted of 30 non-vascular patients of the Ophthalmology Department (group C). We measured the levels of C-reactive protein, fibrinogen, vascular cell adhesion molecule-1 and tumor necrosis factor-alpha, and the titers of IgA and IgG antibodies against C. pneumoniae in the serum of all the patients. Finally, the atheromas and vein segments of group A patients, were immunohistochemically (IHC) examined for the presence of C. pneumoniae.

RESULTS

Peripheral arterial disease (PAD) patients, had significantly higher CRP (p=0.026) and anti-Cp IgA levels (p=0.001) when compared to control subjects, after a multiple linear regression analysis. The odds ratio for the prevalence of femoral atherosclerosis was 3.16 for IgA seropositive patients (CI 1.15-8.67). When comparing group A and group B patients, CRP (p=0.003) and IgA (p=0.011), were significantly correlated with severe PAD. Group A patients with positive immunohistochemical examination of the plaque, had higher anti-Cp IgA levels (p=0.023) and TNF-alpha values (p=0.031), compared to the IHC negative patients. C. pneumoniae was detected in 50% of the femoral atheromas, but in only 3.6% of the veins.

CONCLUSION

This study supports the hypothesis that inflammation (CRP) and chronic C. pneumoniae infection (IgA seropositivity), have an important role in lower limb atherosclerosis and correlate with the severity of the disease.

Lipoprotein-Associated Phospholipase A2 and Measures of Extracoronary Atherosclerosis

OBJECTIVE

Lipoprotein-associated phospholipase A2 (Lp-PLA2) may be a new and independent predictor of cardiovascular events. The effect of Lp-PLA2 may be exerted through effects of the enzyme on the development of atherosclerosis. Therefore, we investigated the association between Lp-PLA2 activity and measures of extracoronary atherosclerosis.

METHODS AND RESULTS

Lp-PLA2 activity was determined in a random sample of 1820 participants from the Rotterdam Study, a population-based cohort study in men and women > or =55 years. Common carotid intima-media thickness, carotid plaques, ankle-arm index, and aortic calcification were examined. Atherosclerosis status could be assigned in 1609 participants. The age-adjusted odds ratio of having atherosclerosis at any site for the highest versus the lowest tertile of Lp-PLA2 activity was 1.86 (95% CI, 1.01 to 3.43) in men and 1.60 (95% CI, 1.08 to 2.37) in women. After additional adjustment for cholesterol, these associations attenuated or even disappeared. The odds ratios of having atherosclerosis at specific sites (carotid arteries and aortic-iliac-femoral tract) followed a similar pattern.

CONCLUSIONS

Although Lp-PLA2 has been found to be independently associated with cardiovascular events, the association with measures of subclinical extracoronary atherosclerosis found in this study strongly attenuated or even disappeared after adjustment for cholesterol.