Risk factors that predict development of microalbuminuria in treated hypertensive men. The Risk Factor Intervention Study Group

Elevated brachial-ankle pulse wave velocity is independently associated with microalbuminuria in a rural population

Microalbuminuria is a marker of generalized endothelial dysfunction resulting from arterial stiffness or insulin resistance, and brachial-ankle pulse wave velocity (baPWV) is a good measure of arterial stiffness. We aimed to investigate whether elevated baPWV is independently associated with microalbuminuria. This study included 1,648 individuals aged over 40 who participated in the baseline Multi-Rural Cohort Study conducted in Korean rural communities between 2005 and 2006. Participants were classified into less than 30 mg/g as normoalbuminuria or 30-300 mg/g as microalbuminuriausing urinary albumin creatinine ratio (UACR). The median and Q1-Q3 baPWV values were significantly higher in the microalbuminuric group both in men (1,538, 1,370-1,777 cm/s vs. 1,776, 1,552-2,027 cm/s, P < 0.001) and women (1,461, 1,271-1,687 cm/s vs. 1,645, 1,473-1,915 cm/s, P < 0.001). BaPWV was independently associated with microalbuminuria in both genders after adjusting for pulse rate; fasting blood glucose; triglyceride; homeostatic model assessment insulin resistance (HOMAIR) and, history of hypertension and diabetes. Fasting blood sugar and HOMAIR were judged as having nothing to do with multicolinearity (r = 0.532, P < 0.001). Elevated baPWV was independently associated with microalbuminuria regardless of insulin resistance among rural subjects over 40 yr.

Glomerular hyperfiltration predicts the development of microalbuminuria in stage 1 hypertension: the HARVEST

Factors related to the development of microalbuminuria in hypertension are not well known. We did a prospective study to investigate whether glomerular hyperfiltration precedes the development of microalbuminuria in hypertension. We assessed 502 never-treated subjects screened for stage 1 hypertension without microalbuminuria at baseline and followed up for 7.8 years. Creatinine clearance was measured at entry. Urinary albumin and ambulatory blood pressure were measured at entry and during the follow-up until subjects developed sustained hypertension needing antihypertensive treatment. Subjects with hyperfiltration (creatinine clearance >150 ml/min/1.73 m2, top quintile of the distribution) were younger and heavier than the rest of the group and had a greater follow-up increase in urinary albumin than subjects with normal filtration (P<0.001). In multivariable linear regression, creatinine clearance adjusted for confounders was a strong independent predictor of final urinary albumin (P<0.001). In multivariable Cox regression, patients with hyperfiltration had an adjusted hazard ratio for the development of microalbuminuria based on at least one positive measurement of 4.0 (95% confidence interval (CI), 2.1-7.4, P<0.001) and an adjusted hazard ratio for the development of microalbuminuria based on two consecutive positive measurements of 4.4 (95% CI, 2.1-9.2, P<0.001), as compared with patients with normal filtration. Age, female gender, and 24 h systolic blood pressure were other significant predictors of microalbuminuria. In conclusion, stage 1 hypertensive subjects with glomerular hyperfiltration are at increased risk of developing microalbuminuria. Early intervention with medical therapy may be beneficial in these subjects even if their blood pressure falls below normal limits during follow-up.

Microalbuminuria and intima-media thickness of the carotid artery in clinically healthy men

Microalbuminuria has been shown to be an independent predictor of cardiovascular disease in different populations. However, the underlying pathophysiological mechanism behind this observation is not known. The purpose of the present cross-sectional study was to examine the relation of microalbuminuria to intima-media thickness (IMT) of the common carotid artery in a group of 368 clinically healthy 58-year old men. Urinary albumin excretion (UAE) and IMT of the common carotid artery were measured. Body mass index, WHR, systolic and diastolic blood pressure, heart rate, High-density lipoprotein (HDL) cholesterol and common carotid artery IMT were associated with UAE. A stepwise forward multiple regression showed that systolic blood pressure and WHR could explain 10.4% of the variability in log UAE (systolic blood pressure beta-coefficient 0.0047, SE 0.001, P<0.001; WHR beta-coefficient 0.93, SE 0.30, P=0.002). In conclusion, UAE was significantly associated with IMT of the common carotid artery in clinically healthy men. However, after adjustment for systolic blood pressure and WHR this association was not significant. We suggest that microalbuminuria in healthy subjects is not primarily associated with atherosclerosis but rather to blood pressure and abdominal obesity.

Factors related to the occurrence of microalbuminuria during antihypertensive treatment in essential hypertension

The objective of the study was to assess the factors related to the occurrence of microalbuminuria during the follow-up of a young adult group with essential hypertension that had not been previously treated. Normo-albuminuric essential hypertensives, <50 years old, who had not been previously treated with antihypertensive drugs and who did not have diabetes mellitus were included. After the initial evaluation, patients were treated using only nonpharmacological measures (n=62), beta-blockers (n=38), ACE inhibitors (n=64), calcium channel blockers (n=8), and several classes (n=15). Measurements were taken for office blood pressure, biochemical profile, and 24-hour urinary albumin excretion at the beginning of the study and were measured yearly during an average of 2.7+/-1.2 years of follow-up. Among the 187 patients included, 22 (11,7%) developed microalbuminuria (progressors, 4.4/100 patients/y). No differences were present between progressors and those who remained normo-albuminuric (nonprogressors) in terms of age, gender, body mass index, disease duration, blood pressure values, biochemical profile, familial history of diabetes or hypertension, smoking habits, or the presence of EKG left ventricular hypertrophy. The group with the lowest progression rate was the patients treated with ACE inhibitors (n=5; 2.9/100 patients/y), followed by the diet group (n=5; 3.3/100 patients/y) and the beta-blockers group (n=5; 4.1/100 patients/y). When we excluded patients treated with calcium channel blockers or those who changed over time between different classes of treatment, no significant differences in the incidence of microalbuminuria were observed among the groups. Progressors showed higher slopes of fasting glucose (4.78+/-11.4 versus 0.50+/-6.8 mg/y, P<0.02) and uric acid (0.58+/-0.93 versus 0.05+/-1.10 mg/y, P<0.03) compared with the slopes of nonprogressors. Both the slopes for glucose and systolic blood pressure over time were associated independently with the slope of the logarithm of urinary albumin excretion when adjusted for age, gender, and treatment groups. Cox proportional hazard model for progression of microalbuminuria showed that baseline urinary albumin excretion (risk ratio [RR]=1.06; confidence interval [CI] 95%, 1.01 to 1.11), slope for systolic blood pressure (RR=1.11; CI 95%, 1.03 to 1.20), and slope for glucose (RR=1.08; CI 95%, 1.03 to 1.14) were independently associated to the development of microalbuminuria. In conclusion, in a group of young adults with essential hypertension that had not been previously treated, the main factors influencing the occurrence of microalbuminuria during antihypertensive treatment were the values of microalbuminuria at baseline and the slopes for systolic blood pressure and fasting glucose.

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.

[Factors associated with changes in microalbuminuria during antihypertensive treatment]

BACKGROUND

The objective of the present study was to analyze the factors related with changes of microalbuminuria during antihypertensive treatment in patients with essential hypertension.

METHODS

One hundred and six patients (57 men, mean age 40.8 [SD 6.6] years) never treated with antihypertensive treatment were included. At the beginning and after one year, blood pressure biochemical profile and urinary albumin excretion (UAE) were measured. After the initial evaluation, 53 patients received angiotensin converting enzyme inhibitors (ACEi) and 53 beta-blockers (BB). Hydrochlorothiazide was added to achieve the blood pressure target < 140/90 mmHg.

RESULTS

The average of UAE was 32.1 (43.1) mg/24 h, and 41 (39%) patients had microalbuminuretics. After 12 months of treatment, a significative fall of systolic BP (-20.6 [8.03] mmHg, p < 0.001), and diastolic BP (-14.18 [10.34] mmHg, p < 0.001) were observed, whereas baseline glucose increases (3.08 [11.07] mg/dl, p = 0.006). The changes of UAE were only related with the baseline UAE values. Neither, age, sex, baseline diastolic BP and changes in diastolic BP were significantly related with the changes in UAE. In spite of similar mean BP reduction (medial BP 17.4 [10.9] vs 14.8 [10.4] mmHg), UAE only was reduced in patients treated with ACEi (LogUAE: 0.203 [0.872] mg/24 h; p < 0.04). In addition, in patients treated with BB a significative increase in baseline glucose (4.4 [12.3] mg/dl; p = 0.013) and uric acid (1.18 [4.18]; p = 0.031) were observed.

CONCLUSIONS

In patients with essential hypertension, changes in microalbuminuria depends of the initial UAE values and the kind of antihypertensive treatment. ACEi produced higher UAE reduction and lower derangement of the glucose metabolism than BB.

Microalbuminuria and pulse pressure in hypertensive and atherosclerotic men

To identify the biological covariates of microalbuminuria (albuminuria >/=15 microg/min) in nondiabetic subjects, brachial blood pressure, echocardiographic left ventricular mass, and other cardiovascular and metabolic parameters were evaluated in 211 untreated males (38 normal controls, 109 uncomplicated stage 1 to 3 essential hypertensives, and 64 patients with clinically stable atherosclerotic peripheral vascular disease either with [n=44] or without [n=20] essential hypertension) with normal cardiac and renal function. Compared with normoalbuminuric subjects, microalbuminuric subjects (n=67) were characterized by higher systolic blood pressure, comparable diastolic blood pressure, and, therefore, wider pulse pressure. Greater prevalence of hypertension, peripheral vascular disease, left ventricular hypertrophy, and reduced HDL cholesterol values further distinguished microalbuminuric from normoalbuminuric subjects in univariate comparisons. The risk of microalbuminuria increased by ascending pulse pressure quintiles in age-corrected logistic regression models, in which pulse pressure was more predictive than systolic pressure and was independent of mean pressure. When microalbuminuric status was regressed against a series of dichotomous (vascular and active smoker status) and continuous (age, pulse and mean pressure, left ventricular mass index, and HDL and LDL cholesterol) variables, only pulse pressure, left ventricular mass index, and smoking status were independent predictors. The association of increased albuminuria with wider pulse pressure, a correlate of the pulsatile hemodynamic load and conduit vessel stiffness as well as an important cardiovascular risk factor, may explain why microalbuminuria predicts cardiovascular events in nondiabetic subjects. The independence from concomitant vascular disease also suggests that wider pulse pressure, rather than representing a simple marker for atherosclerotic disease, influences albuminuria directly.