Microalbuminuria and markers of the atherosclerotic process: the D.E. S.I.R. study

High sensitivity C-reactive protein in systemic lupus erythematosus: relation to disease activity, clinical presentation and implications for cardiovascular risk

Measurement of high sensitivity C-reactive protein (hs-CRP), has been used in the assessment of disease activity in numerous rheumatic conditions including systemic lupus erythematosus (SLE). However, the utility of hs-CRP measurement in patients with lupus is uncertain. This study examined if hs-CRP can be used to assess disease activity, severity and cardiovascular risk in SLE. Serum samples from 601 visits of 213 SLE patients and 134 controls were analysed for hs-CRP by nephelometry. Detailed demographic data were obtained from all subjects and medication history and key laboratory parameters were collected. Disease activity was assessed using the SLEDAI. High sensitivity CRP was not associated with disease activity (SLEDAI), number of ACR SLE criteria or presence of any particular organ involvement. hs-CRP levels were significantly correlated with standard cardiovascular risk factors including body weight ( P = 0.0002), hypertension ( P = 0.001), and apolipoprotein A-I ( P < 0.0001). Interestingly an inverse correlation was seen between hs-CRP levels and antimalarial use ( P = 0.0018). Our results suggest that measurement of hs-CRP, though not valuable as marker of disease activity in SLE may be of some use in the assessment of cardiovascular risk. We speculate that antimalarials may help to reduce cardiovascular risk in patients with SLE.

An association of a variety of cardiovascular risk factors with low grade albuminuria in Korean men

BACKGROUND

Recent studies have challenged the original definition of microalbuminuria when used to assess the risk of coronary heart disease or death. However, no large study has been conducted on Asian subjects regarding this topic to date. Therefore, we investigated the relationship between albuminuria below 17 microg/mg and other cardiovascular risk factors in apparently healthy Korean men.

METHODS

We enrolled 2474 men with albuminuria below 17 microg/mg to participate in this study. We evaluated a variety of cardiovascular risk factors as well as the urine albumin creatinine ratio (UACR). The subjects were stratified into five groups by their UACR values and comparisons were made among the five groups.

RESULTS

The comparisons showed that the UACR was progressively higher in subjects with a larger waist circumference and BMI as well as higher values for: serum triglyceride, glucose, hsCRP, and the systolic BP, in addition to a higher prevalence of diabetes and metabolic syndrome. When we excluded subjects with hypertension and diabetes, the results were similar.

CONCLUSIONS

Our findings suggest that low grade albuminuria in Korean men was associated with a variety of cardiovascular risk factors, and this finding was unchanged when we excluded subjects with diabetes and hypertension. Further studies are warranted to evaluate the clinical implications of our findings.

Protection of the kidney by thiazolidinediones: An assessment from bench to bedside

The global epidemic of diabetes mellitus has led to a continuous increase in the prevalence of diabetic nephropathy over the past years. Thus, diabetic nephropathy is currently the number one cause of end-stage renal disease in the Western world. It represents a major public health problem for which more effective prevention and treatment strategies are needed. Thiazolidinediones (TZDs) are a class of agents that lower blood glucose through reduction of insulin resistance in patients with type 2 diabetes. Growing evidence support the concept that TZDs have several beneficial effects on the cardiovascular system beyond their effects on glycemic control. These benefits include: blood pressure lowering, triglyceride reduction, high-density lipoprotein-cholesterol elevation, and reduction in subclinical vascular inflammation. Moreover, data from several animal and human studies support the notion that TZDs reduce urine albumin excretion and may prevent development of renal injury. The relative lack of evidence, however, demonstrating the effects of TZDs on hard renal outcomes mandates the need for well-designed trials with this particular objective. This paper summarizes all the data from clinical and experimental studies relevant to a possible renoprotective effect of TZDs and discusses actions of these compounds that may contribute toward this effect.

Waist circumference and the metabolic syndrome predict the development of elevated albuminuria in non-diabetic subjects: the DESIR Study

OBJECTIVE

Metabolic determinants of microalbuminuria remain poorly understood in non-diabetic individuals and particularly in women. We investigated in both sexes whether an elevated waist circumference (WC) or the presence of the metabolic syndrome (MetS) predict the development of elevated albuminuria at 6 years.

DESIGN AND PATIENTS

We studied 2738 subjects from the DESIR cohort without microalbuminuria or diabetes at baseline and who were followed up for 6 years.

RESULTS

At 6 years, 254 individuals [9.3%; 95% confidence interval (CI) 8.2-10.4%] had developed elevated albuminuria (> or = 20 mg/l), which was significantly and positively associated with WC and blood pressure, but not with fasting glucose, lipids or body mass index in either sex. In both sexes, subjects with a high WC or with MetS at baseline were more likely to develop elevated albuminuria at 6 years compared with those with a normal WC or absence of MetS. In multivariate logistic analysis, WC as a continuous variable or a WC of 94 cm or greater for men and a WC greater than 88 cm for women were predictive of the development of elevated albuminuria, after adjusting for age, hypertension, the use of angiotensin-converting enzyme inhibitors, fibrinogen and glycaemia. MetS was a risk factor for elevated albuminuria in men (odds ratio 1.87; 95% CI 1.25-2.81), with differences according to the MetS definition.

CONCLUSION

Abdominal adiposity is related to the development of elevated albuminuria in both sexes, suggesting that the measurement of WC may improve the identification of non-diabetic individuals at risk of developing microalbuminuria and emphasizing the interest of screening for albuminuria among those with MetS.

Microalbuminuria, renal function and development of sustained hypertension

OBJECTIVE

Microalbuminuria (MA) is a marker of adverse outcome in hypertension. The aim of this study was to investigate the association of MA with cardiovascular risk factors and glomerular hyperfiltration in the early stage of hypertension and to assess its predictive value for the development of sustained hypertension requiring antihypertensive treatment.

DESIGN AND PARTICIPANTS

We studied 1041 young stage 1 hypertensive subjects. Study variables were 24-h ambulatory blood pressure and heart rate, anthropometric measures, metabolic variables, creatinine clearance and lifestyle factors analyzed as a function of ascending urinary albumin measured from 24-h collections. Subjects were followed until they developed sustained hypertension and were eligible for antihypertensive medication according to current guidelines.

SETTING

Seventeen outpatient clinics in Italy.

RESULTS

Eighty-five percent of the subjects were normoalbuminuric, 9% had borderline MA, and 6% had overt MA. No between-group differences were found for age, body mass index, heart rate, lifestyle factors and biochemistry in both genders. Creatinine clearance was greater in the subjects with overt MA and borderline MA than in the normoalbuminuric subjects (P = 0.003 and 0.011, respectively). In a two-way ANCOVA, microalbuminuric subjects both with hyperfiltration (P < 0.001) and with normal filtration (P = 0.04) had higher 24-h systolic blood pressure than subjects with normoalbuminuria and normal filtration. In a Cox analysis, neither MA nor hyperfiltration were significant predictors of development of sustained hypertension.

CONCLUSION

MA is not associated with an adverse metabolic risk profile in the early stage of hypertension. MA is associated with greater hemodynamic load and with glomerular hyperfiltration in this clinical setting, but does not help in predicting those subjects destined to develop sustained hypertension requiring antihypertensive therapy.

Acute-phase proteins and microalbuminuria among patients with type 2 diabetes

OBJECTIVE

to determine the relationship between acute-phase proteins and microalbuminuria in type 2 diabetic patients without clinical evidence of macrovascular disease.

RESEARCH DESIGN AND METHODS

We studied cross-sectionally 64 non-smoking outpatients with type 2 diabetes mellitus without clinical evidence of cardiovascular disease attended at Brazilian University General Hospital aged 59.5 +/- 8.1 years and with a known duration of diabetes of 11.5 +/- 8 years. Urinary albumin excretion rate (AER) was determined in timed overnight urine samples. Serum alpha(1)-acid glycoprotein (AGP) and plasma fibrinogen were determined by immunoturbidimetry assay and serum C-reactive protein (CRP) was measured by a high-sensitive immunonephelometry assay.

RESULTS

A higher levels of AGP (P = 0.0000), CRP (P= 0.003) and fibrinogen ( P = 0.0001) were found in microalbuminuric (n = 26) than in normoalbuminuric patients ( n = 38). All the acute-phase proteins were correlated with each other and with AER, respectively (r = 0.67 for AGP; 0.35 for fibrinogen, and 0.41 for CRP, P < 0.01 for all). Stepwise multiple regression analysis showed that AGP was independently associated with AER along with systolic blood pressure (r2 = 0.49, P = 0.000). Logistic regression analysis showed that AGP was independently related to microalbuminuria with an odds ratio (95% CI) of 1.16 ((1.08-1.24), P = 0.000).

CONCLUSIONS

According to our results acute-phase proteins a known markers of chronic inflammation were associated with microalbuminuria independently of clinical cardiovascular disease. The influence of AGP on AER and microalbuminuria needs to be confirmed in prospective studies. Intervention studies are necessary to assess whether anti-inflammatory treatment would have a beneficial effect on this chronic complication of diabetes.

The relationship of cardiovascular risk factors to microalbuminuria in older adults with or without diabetes mellitus or hypertension: the cardiovascular health study

BACKGROUND

Microalbuminuria is a risk factor for coronary heart disease (CHD). It occurs most commonly in the settings of diabetes and hypertension. The mechanisms by which it increases CHD risk are uncertain.

METHODS

We examined the cross-sectional association of microalbuminuria with a broad range of CHD risk factors in 3 groups of adults aged 65 years or older with and without microalbuminuria: those with (1) no diabetes or hypertension (n = 1,098), (2) hypertension only (n = 1,450), and (3) diabetes with or without hypertension (n = 465).

RESULTS

Three factors were related to microalbuminuria in all 3 groups: age, elevated systolic blood pressure, and markers of systemic inflammation. In patients with neither diabetes nor hypertension, increasing C-reactive protein levels were associated with microalbuminuria (odds ratio per 1-mg/L increase, 1.46; 95% confidence interval [CI], 1.15 to 1.84). Among those with diabetes, an increase in white blood cell (WBC) count was associated with microalbuminuria (odds ratio per 1,000-cell/mL increase, 2.57; 95% CI, 1.12 to 5.89). Among those with hypertension, an increase in WBC count (odds ratio per 1,000-cell/mL increase, 1.83; 95% CI, 1.04 to 3.23) and fibrinogen level (odds ratio per 10-mg/dL increase, 1.02; 95% CI, 1.00 to 1.05) were significantly associated with microalbuminuria. In all 3 groups, prevalent CHD was related to an elevated WBC count. In none of the 3 groups was brachial artery reactivity to ischemia, an in vivo marker of endothelial function, related to microalbuminuria.

CONCLUSION

Microalbuminuria is associated with age, systolic blood pressure, and markers of inflammation. These associations reflect potential mechanisms by which microalbuminuria is related to CHD risk.

Angiotensin-converting enzyme genotype, albuminuria and plasma fibrinogen in type 2 diabetes mellitus

AIMS

Increased fibrinogen level is considered an important atherosclerosis risk factor. Patients with type 2 diabetes frequently have increased fibrinogen levels. The aim of the present study was to examine the effect of angiotensin-converting enzyme (ACE) gene polymorphism and the effects of the diabetic environment on plasma fibrinogen in type 2 diabetes.

PATIENTS AND METHODS

The study group included 125 patients with type 2 diabetes (40 men, 85 women). The average age of patients was 62 +/- 10 years. Fibrinogen concentration was determined with the thrombin coagulation test. ACE insertion/deletion (I/D) polymorphism was detected using polymerase chain reaction (PCR) assay.

RESULTS

II homozygotes (n = 17) had the highest mean fibrinogen levels, ID heterozygotes (n = 75) had medium levels and DD homozygotes (n = 33) had the lowest (p = 0.054, ANOVA). II homozygotes also had significantly higher mean fibrinogen level than ID/DD carriers (4.3 +/- 1.7 vs. 3.5 +/- 1.3 g/l; p = 0.015). The indices of renal functions, i.e. albuminuria (r = 0.37; p < 0.0001) and serum creatinine (r = 0.22; p = 0.015), significantly correlated with fibrinogen levels. The correlation between albuminuria and fibrinogen was significant in the subgroups with genotypes II (r = 0.76; p = 0.001) and ID (r = 0.37, p = 0.002), whereas in the subgroup of DD homozygotes this relationship did not reach statistical significance. In the multivariate regression analysis with age, sex, BMI, creatinine, albuminuria and ACE genotype as independent variables, albuminuria was the only significant predictor of fibrinogen level (p < 0.0001). After interaction between the ACE genotype and albuminuria was included into multivariate analysis, the interaction became the only independent predictor of plasma fibrinogen level (p < 0.0001) in the model, and the model explained 25% of the plasma fibrinogen variance.

CONCLUSION

ACE gene polymorphism is associated with plasma fibrinogen level in type 2 diabetes. This association is mediated by an interaction between ACE genotype and albuminuria. Diabetes patients with genotypes II or ID have increased plasma fibrinogen in the presence of albuminuria.

Beneficial effects of metformin on haemostasis and vascular function in man

Type 2 diabetes is characterised by insulin resistance in association with clustering of atherothrombotic risk factors (dysglycaemia, hyperinsulinaemia, hypertension, raised triglyceride, low HDL cholesterol and increased levels of plasminogen activator inhibitor-1 (PAI-1) and clotting factor VII). There is a 3-5 fold increase in risk of myocardial infarction rising to 10-20 fold in the presence of microalbuminuria and overall around 70-75% of subjects with type 2 diabetes die of cardiovascular disease. However, classical risk factors which associate with insulin resistance do not account for all the increased burden of vascular disease in diabetic subjects. Metformin is a biguanide compound which is antihyperglycaemic, reduces insulin resistance and has cardioprotective effects on lipids, thrombosis and blood flow. Metformin has a weight neutral/weight lowering effect and reduces hypertriglyceridaemia, elevated levels of PAI-1, factor VII and C-reactive protein. In addition recent studies indicate that metformin has direct effects on fibrin structure/function and stabilises platelets, two important components of arterial thrombus. The United Kingdom Prospective Diabetes Study (UKPDS) reported that metformin was associated with a 32% reduction in any diabetes related endpoint (p<0.002), a 39% reduction in myocardial infarction (p<0.01) and a non-significant 29% fall in microvascular complications. The figures for macrovascular complications compare favourably for those described for other cardioprotective agents such as ACE inhibitors and statins. These findings confirm metformin as first line therapy in the management of obese insulin resistant type 2 diabetes and in the prevention of the vascular complications of this common condition.

Microalbuminuria in hypertension

A body of evidence indicates that microalbuminuria is a well-recognized marker of cardiovascular complications and increased cardiovascular risk in hypertension. However, the prognostic significance of microalbuminuria remains controversial because only the results of a few prospective studies performed in small groups of hypertensive subjects without diabetes mellitus are available. Several factors can affect the prevalence of microalbuminuria in hypertension including age, sex, race, severity of the disease, and concomitant risk factors. This accounts for the large differences in the prevalence of microalbuminuria that can be found in the literature, with prevalence rates going from a low of 4.7% to a high of 46%. The main determinant of albumin excretion rate in subjects with mild hypertension and no cardiovascular complications seems to be the hemodynamic load, whereas in subjects with more severe hypertension and associated target organ damage, the augmented urinary albumin leak is probably the consequence of glomerular damage. Inhibition of the renin-angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists is particularly effective at reducing the albumin excretion rate, but whether these classes of drugs are more beneficial in patients with microalbuminuria remains to be determined. There is general consensus that evaluation of microalbuminuria is useful for the assessment of overall cardiovascular risk in hypertension, since albumin excretion rate appears to be a cost-effective way to identify patients at higher risk for whom additional preventive and therapeutic measures are advisable.

Microalbuminuria, an integrated marker of cardiovascular risk in essential hypertension

This paper reviews the existing epidemiological and clinical evidence about the relationships of non-diabetic microalbuminuria with cardiovascular risk factors such as elevated blood pressure (BP), systolic particularly, cardiac hypertrophy, adverse metabolic status, smoking habits, elevated angiotensin II levels, endothelial dysfunction, acute and perhaps subclinical inflammation. Because of that unique property of reflecting the influence of so many clinically relevant parameters, microalbuminuria may legitimately be defined as an integrated marker of cardiovascular risk, an unique profile among the several prognostic predictors available to stratify risk in hypertensive patients. Recent cohort studies also showed associations with cardiovascular morbidity and mortality independently from conventional atherogenic factors. This behaviour, whose understanding still needs further elucidation, suggests to measure albuminuria and to screen patients at a higher absolute risk in whom preventive treatment is expected to be more beneficial than in those with a lower absolute risk.

Non-diabetic microalbuminuria, endothelial dysfunction and cardiovascular disease

Subclinical increases in albuminuria (microalbuminuria) predict morbid events, but the reasons for that are still not understood in full. This paper reviews the existing evidence regarding the relationships of non-diabetic microalbuminuria and cardiovascular disease, the underlying assumption being that endothelial dysfunction contributes both to atherosclerotic macrovascular disease and renal microvascular disease of which albuminuria is a marker. Much data support that concept, and suggest a preferential link with endothelial activation in response to acute and subclinical inflammatory stimulation, although further studies are needed to establish the exact cause-effect mechanisms. Epidemiological studies also show associations with cardiovascular events, and some recent prospective results also indicate the power of microalbuminuria to predict risk independently from conventional atherogenic factors. Thus, microalbuminuria might be considered as an integrated marker of cardiovascular risk sensitive to systemic vascular status in addition to other parameters such as blood pressure levels, glucose metabolism, smoking habits, a profile rather unique among the prognostic predictors available to stratify risk in hypertensive patients.