The prognostic significance of proteinuria: the Framingham study

Renal protection by antihypertensive therapy

The attainment of adequate renal protection requires strict blood pressure control and a diminution of proteinuria or microalbuminuria to values as near from normalcy as possible. It has been considered that by getting the first, the second could be attained at the same price. Recent data have confirmed that renal protection in hypertensive patients, diabetics or not, requires combination therapy that has to include an angiotensin converting enzyme inhibitor or an angiotensin receptor blocker. A calcium channel blocker can be added to this without renal compromise. A diuretic will also be needed in most cases. Proteinuria will diminish with this combination in particular if up-titration of the drug blocking the effects of angiotensin II is performed. The control of other associated risk factors is also required, in particular smoking and lipids.

Dipstick proteinuria: can it guide hypertension management?

Recent guidelines call for lower blood pressure targets in patients with proteinuria of 1 g/d or greater. Dipstick test for proteinuria is widely available, but no information on its sensitivity or specificity is available when implementing current guidelines. To determine performance characteristics of dipstick proteinuria, we studied 332 patients attending a Veterans Administration renal clinic who underwent simultaneous measurement of urine protein and creatinine, as well as automated urinalysis with a dipstick graded from 0 to 4+ with a machine reader. There was increasing severity of proteinuria with each increment in dipstick result. When the spot urine protein-creatinine ratio was less than 1, a lower specific gravity was associated with greater severity of proteinuria. Areas under the receiver operating characteristic curve for 1 and 3 g protein/g creatinine were 0.945 and 0.905, respectively. This attests to the excellent performance of the urine dipstick. The likelihood of having a protein-creatinine ratio of 1 or greater was 7% when urine dipstick protein value was 1+ or 2+, 62% when dipstick protein value was 3+, and 92% when dipstick protein value was 4+. Thus, dipstick proteinuria assessed by an automated reader remains a useful test to predict the severity of proteinuria and can be used to guide therapy. A cutoff dipstick proteinuria value of 3+ has the best combination of sensitivity and specificity (96% and 87%, respectively) in predicting a protein-creatinine ratio of 1 or greater and a cutoff value of 4+ in predicting a protein-creatinine ratio of 3 or greater (sensitivity, 94%; specificity, 83%). These results suggest that patients with 3+ or greater proteinuria should not only trigger appropriate evaluation of proteinuria, but also have mean arterial pressures targeted to less than 92 mm Hg.

Diagnosing coronary artery disease in diabetic patients

Although several diagnostic modalities are available to the clinician interested in diagnosing coronary artery disease, very few have been validated in diabetic populations. This review discusses the non-invasive diagnosis of coronary disease in diabetic patients. Evidence regarding the prevalence and prognostic significance of silent ischemia is reviewed and the potential impact of silent ischemia on the diagnostic characteristics of the exercise treadmill test discussed. Other diagnostic tools are considered, and recommendations are made with respect to screening asymptomatic diabetic patients for coronary artery disease.

The risk of cardiovascular disease associated with proteinuria in renal transplant patients

Proteinuria in the general population has been shown to be associated with cardiovascular disease, which is the main cause of death in renal transplantation. We investigated the effect of proteinuria on cardiovascular disease after renal transplantation in 532 renal transplant patients with functioning grafts for more than 1 year. Patients were classified into two groups depending on the presence of persistent proteinuria. We analyzed graft and patient survival, posttransplantation cardiovascular disease, and main causes of graft loss and death. Five- and 10-year graft and patient survival rates were lower in the group with proteinuria. The main cause of death was vascular disease in both groups. The presence of posttransplantation cardiovascular disease was higher in the group with proteinuria. Persistent proteinuria was associated with graft loss (RR=4.18), patient death (RR=1.92), and cardiovascular disease (RR=2.45). In conclusion, persistent proteinuria was an independent risk factor for increased cardiovascular morbidity and mortality in renal transplant patients.

Epidemiologic appraisal of hypertension as a coronary risk factor in the elderly

Five decades of epidemiologic research has established elevated blood pressure as a major contributor to atherosclerotic cardiovascular diseases in the elderly, including coronary heart disease. Clinicians formerly favored the diagnosis and treatment of hypertension in terms of the diastolic blood pressure and categorical "hypertension." Epidemiologic data now emphasize the essential role of systolic blood pressure, pulse pressure, and a graded influence of blood pressure, even within the high-normal range. The risk of coronary heart disease, the most common lethal sequela of hypertension, increases with the extent of risk factor clustering. Among hypertensive persons, about 39% of coronary events in men and 68% in women are attributable to the presence of two or more additional risk factors. When risk factor clustering is associated with glucose intolerance, obesity, and dyslipidemia, it may be attributed to insulin resistance promoted by abdominal obesity. Other hazardous influences often accompanying hypertension in the elderly are the presence of an elevated heart rate, elevated levels of fibrinogen, and left ventricular hypertrophy. Because clustering with other risk factors is characteristic of hypertension in the elderly, it is essential to screen for them and for the presence of comorbid cardiovascular diseases, target organ disease, and subclinical vascular disease likely to be present. Multivariate risk assessment profiles enable global estimation of hypertensive risk of developing coronary heart disease. Hypertensive elderly patients are more appropriately targeted for antihypertensive therapy by such risk stratification than by relying solely on the severity of the blood pressure elevation. The goal of therapy should be to improve the multivariate risk profile as well as the level of the blood pressure.

Prevalence and correlates of diabetes mellitus in a screened cohort in Okinawa, Japan

The incidence of end-stage renal disease due to diabetes mellitus (DM) is increasing. There have been too few epidemiological studies of the predictors of DM nephropathy, particularly type 2 DM, among a statistically significant population. We studied the prevalence and correlates of DM in a screened cohort in Okinawa, Japan. A total of 9,914 screenees (6,163 men and 3,751 women) over 18 years of age underwent a 1-day health check at the Okinawa General Health Maintenance Association between April 1997 and March 1998. Subjects were considered to have DM if they showed a fasting plasma glucose > or = 126 mg/dl and hemoglobin A1c > or = 7.0%, or if they were receiving treatment for DM. Non-DM subjects were followed-up until March 2000 to see whether or not they developed DM. Relative risk for developing DM was evaluated by Cox proportional hazard analysis after adjusting for confounding variables. A total of 673 screenees (520 men and 153 women) were diagnosed with DM. The prevalence of DM was 67.9 per 1,000 screenees (84.4 for men and 40.8 for women). A total of 7,125 non-DM screenees were examined a second time. Among them, 164 screenees (130 men and 34 women) had developed DM during the follow-up period. Over 2 years, the cumulative incidence of DM was 2.3% (2.9% in men and 1.3% in women). The adjusted relative risk (95% confidence interval) for developing DM was highest for proteinuria, or 1.90 (1.14-3.17). The results indicated that the prevalence and incidence of DM were high among this screened cohort in Okinawa, Japan. Subjects with proteinuria may thus be at high risk for developing DM.

Routine renin-angiotensin system blockade in renal transplantation?

There is ample evidence to support the recommendation of renin-angiotensin system blockade therapy as the standard of care for strategies aimed at preserving renal function in chronic renal disease. Nevertheless, despite the well established antihypertensive effects of these drugs, the use of renin-angiotensin system blockers in renal transplantation has been quite limited so far, nephrologists being afraid of the possibility of inducing renal insufficiency in patients with a single kidney transplant. However, current knowledge of the ability of these agents to control blood pressure and urinary protein excretion, as well as post-transplant erythrocytosis, effectively in kidney transplant recipients suggests that it is now time to apply renin-angiotensin system blockers to the field of renal transplantation.

Renal function: the Cinderella of cardiovascular risk profile

The presence of an altered renal function in essential hypertension, advanced heart failure (HF) and after a myocardial infarction (MI) is associated with higher cardiovascular morbidity and mortality. Indices of altered renal function (e.g., microalbuminuria, increased serum creatinine concentrations, decrease in estimated creatinine clearance or overt proteinuria) are independent predictors of cardiovascular morbidity and mortality in any of the three clinical situations. These parameters should then be routinely evaluated in clinical practice. These facts have several therapeutic implications. First, although there is no evidence-based information on the level of blood pressure that confers optimal renal protection, levels substantially lower than past recommendations are advisable. Second, hypertensive kidney damage should be prevented by early treatment of hypertensive patients, particularly those with microalbuminuria. Finally, to avoid further aggravation of high cardiovascular risk, antihypertensive agents devoid of unwanted metabolic side effects should be used for the treatment of hypertensive vascular damage. In HF, the combination of an angiotensin-converting enzyme (ACE) inhibitor and a beta-blocker seem to be the most renoprotective. Renal outcome is also improved by ACE inhibition after an MI. Finally, renal and cardiovascular outcome seem to run in parallel in all these situations.

Proteinuria after renal transplantation affects not only graft survival but also patient survival

BACKGROUND

Proteinuria is associated with an increased risk of renal failure. Moreover, proteinuria is associated with an increased death risk in patients with diabetes mellitus or hypertension and even in the general population.

METHODS

One year after renal transplantation, we studied the influence of the presence of proteinuria on the risk of either graft failure or death in all 722 recipients of a kidney graft in our center who survived at least 1 year with a functioning graft. Proteinuria was analyzed both as a categorical variable (presence versus absence) and as a continuous variable (quantification of 24 hr urine). Other variables included in this analysis were: donor/recipient age and gender, original disease, race, number of HLA-A and HLA-B mismatches, previous transplants, postmortal or living related transplantation, and transplantation year. At 1 year after transplantation, we included: proteinuria, serum cholesterol, serum creatinine, blood pressure, and the use of antihypertensive medication.

RESULTS

In the Cox proportional hazards analysis, proteinuria at 1 year after transplantation (both as a categorical and continuous variable) was an important and independent variable influencing all endpoints. The influence of proteinuria as a categorical variable on graft failure censored for death showed no interaction with any of the other variables. There was an adverse effect of the presence of proteinuria on the graft failure rate (RR=2.03). The influence of proteinuria as a continuous variable showed interaction with original disease. The presence of glomerulonephritis, hypertension, and systemic diseases as the original disease significantly increased the risk of graft failure with an increasing amount of proteinuria at 1 year. The influence of proteinuria as a categorical variable on the rate ratio for patient failure was significant, and there was no interaction with any of the other significant variables (RR=1.98). The death risk was almost twice as high for patients with proteinuria at 1 year compared with patients without proteinuria. The influence of proteinuria as a continuous variable was also significant and also without interaction with other variables. The death risk increased with increasing amounts of proteinuria at 1 year. Both the risks for cardiovascular and for noncardiovascular death were increased.

CONCLUSION

Proteinuria after renal transplantation increases both the risk for graft failure and the risk for death.

Vascular function of the peripheral circulation in patients with nephrosis

BACKGROUND

Nephrotic syndrome is associated with abnormal lipoprotein metabolism and increased risk of coronary heart disease. Endothelial dysfunction, an early phase of atherogenesis that manifests as impaired flow-mediated dilation (FMD) of the peripheral circulation, may link these associations.

METHODS

We examined endothelial function of the brachial artery and forearm resistance arteries in 15 patients with nephrosis (NP), 15 patients with primary hyperlipidemia (HL) alone, and 15 normolipidemic, nonproteinuric subjects (NC) matched for age, sex, and weight. The NP and HL groups had similar serum cholesterol and triglyceride concentrations. Post-ischemic FMD (endothelium-dependent) and glyceryl trinitrate-mediated dilation (GTNMD; endothelium-independent) of the brachial artery were studied using ultrasonography and computerized edge detection software. Postischemic forearm blood flow was also measured using plethysmography.

RESULTS

Postischemic FMD of the brachial artery was significantly lower in the NP and HL groups compared with NC group (mean +/- SE): NP 4.91 +/- 0.8%, HL 4.53 +/- 0.6%, NC 8.45 +/- 0.5% (P < 0.001). There were no significant differences among the groups in baseline diameter and GTNMD of the brachial artery, nor in maximal forearm blood flow and flow debt repayment of the forearm microcirculation. Significant differences in FMD among the groups were principally related to differences in serum low-density lipoprotein cholesterol.

CONCLUSIONS

Patients with NP have abnormal endothelium-dependent but preserved endothelium-independent dilation of the brachial artery following an ischemic stimulus. Postischemic forearm microcirculatory function is unimpaired. Dyslipoproteinemia is probably the principal cause of endothelial dysfunction of conduit arteries in patients with NP and the basis for their increased risk of cardiovascular disease.

Cardiovascular mortality in non-insulin-dependent diabetes mellitus. A controlled study among 683 diabetics and 683 age- and sex-matched normal subjects

Although non-insulin-dependent diabetes mellitus (NIDDM) is considered a major cause of death, the role of some independent risk factors in diabetic patients is under debate. In fact the prognosis of NIDDM diabetes varies considerably in relation to the individual risk pattern, and the different studies are not directly comparable because of differences in size, age and geography of the samples, and type of statistical analysis. The aim of the study is to identify the independent predictors of mortality in a cohort of subjects with NIDDM, and to verify whether the relative risk (RR) of cardiovascular mortality is different in comparison to that of coeval non-diabetic subjects from a general population. The study includes 683 patients with NIDDM from the Northern Italian town of Pordenone, followed up for 6 years and age- and sex-matched to 683 non-diabetic subjects from a Northern Italian general population. When the two cohorts were compared, NIDDM turned out to be a strong risk factor for cardiovascular mortality (RR: 2.67). Age, coronary artery disease (RR: 1.78), arterial hypertension (RR: 1.39), macro- (RR: 2.97) and microalbuminuria (RR: 2.01) were independent predictors of cardiovascular mortality in the diabetics. In conclusion, survival of diabetic patients is worse than that of non-diabetic coeval subjects. Only few items are able to predict cardiovascular mortality in the diabetics, namely age, hypertension, CAD, macro- and microalbuminuria.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

A computationally simple test of homogeneity of odds ratios for twin data

It is of interest to compare measures of association of binary traits among samples of bivariate data. One example is the comparison of association within a sample of monozygotic (MZ) twins to that within a sample of dizygotic (DZ) twins. A larger association in the MZ twins suggests that the trait of interest may have a genetic component. The Bivariate data in this example are binary traits for the twins in each pair. Another example is the comparison of a measure of Hardy-Weinberg disequilibrium across several populations. The bivariate data in this example are the two alleles comprising the genotype of interest. We propose using derived logistic regression equations from the full exponential model for the bivariate outcomes to test for homogeneity. We adjust for correlation among outcomes via generalized estimating equations. This modeling approach allows for adjustment for individual-level and pair-level covariates and thereby allows for testing for gene x environment interactions. Further, we extend the model to allow for simultaneous analysis of two diseases, which allows for testing for a genetic component to the coaggregation of two diseases. In contrast to approaches proposed by previous authors, no special software is required; our approach can be easily implemented in standard software packages. We compare our results to those of other methods proposed in the literature for data from the Vietnam Era Twins Study. We apply our methods also to the Anqing Twin Study and to data on major depression and generalized anxiety disorder from the Virginia Twin Register.

Microproteinuria and long-term prognosis with respect to renal function and survival in normotensive and hypertensive women--a 24-year follow-up of a representative population sample of women in Gothenburg, Sweden

OBJECTIVE

This study aimed to assess albuminuria and subclinical proteinuria, their association with hypertension and their role as predictors of hypertension, impaired renal function and mortality.

MATERIAL AND METHODS

A baseline population study comprising 1462 women in five different age groups in Gothenburg, Sweden, was carried out in 1968-69. Comprehensive clinical examinations and laboratory tests were performed, including blood pressure measurement and an Albustix test. A systematic subsample of women additionally collected a 24 h urine sample for quantitative protein analysis. Values of urinary protein (u-protein) excretion between 80 and 300 mg/24 h were defined as microproteinuria. The results described in this paper are based on a 24-year follow-up.

RESULTS

The baseline Albustix test was positive in 6.8% of 1458 women, from whom a urine sample was obtained. Of 741 baseline urine collections for u-protein excretion, 16.9% were in the microproteinuric range (80-300 mg/24 h), 1.1% in the macroproteinuric range (> 300 mg/24 h) and 82.1% in the normoproteinuric range (< 80 mg/24 h). Hypertension was more common in Albustix-positive women than in those with negative Albustix, and hypertension was also more prevalent in women with microproteinuria than in women with normoproteinuria. Neither positive Albustix nor microproteinuria was related to later renal impairment. Hypertension was associated with increased mortality in both Albustix-positive and Albustix-negative women, and in women with both normoproteinuria and microproteinuria at baseline. The mortality ratio during the follow-up period was, however, not significantly influenced by positive Albustix or by microproteinuria at baseline, in either hypertensive or non-hypertensive women.

CONCLUSIONS

This study demonstrated that both a positive Albustix test and microproteinuria were associated with hypertension. Hypertension at baseline increased the risk for death during the follow-up period, while neither albuminuria, defined as a positive Albustix test, nor microproteinuria was associated with an impaired long-term prognosis with respect to renal function or survival in this cohort of Swedish middle-aged women during 24 years of follow-up. Microproteinuria in otherwise healthy normotensive or hypertensive women does not appear to impair the long-term prognosis.

Screening for proteinuria in Japanese schoolchildren: a new approach

By governmental mandate, Japanese school children are screened annually for proteinuria, hematuria, and glucosuria to identify children with possible renal disorders. We added urine dipstick tests for albumin and creatinine to the Japanese screening protocol, and used their dipstick results for blood, glucose and protein. The sulfosalicylic acid precipitation test was used to confirm "trace" positive protein dipsticks. The Japanese and our screening protocol have in common the same data for glucosuria and proteinuria. Their scheme has an algorithm for repeat testing of children with abnormal results, and further testing and medical evaluation for those showing persistently abnormal values. Out of the 23,121 students, we found seven with likely nephritis, one with confirmed nephritis, one with nephrotic syndrome, 170 with persistent unexplained hematuria, 19 with persistent unexplained proteinuria, 14 cases of urinary tract infection, and 20 cases of likely diabetes mellitus. We conclude that dipstick testing for albumin, protein, creatinine, glucose and occult blood has significant value in a multilevel testing scheme for identifying children with urinary tract abnormalities or diabetes. The assay of albumin increases the sensitivity of the screening, and dividing the albumin by the creatinine concentration reduces the potential errors arising from concentrated or dilute urines.

Effects of current smoking and smoking discontinuation on renal function and proteinuria in the general population

BACKGROUND

Smoking may adversely affect the progression of renal diseases. However, it is unknown whether smoking affects renal function in subjects without nephropathy.

METHODS

In 1998, 28,409 volunteers from the general population were examined at the Institut Régional pour la Santé (IRSA). Renal function was estimated with creatinine clearance using the Cockcroft formula. Dipstick proteinuria was assessed on an overnight urine sample by a trained technician.

RESULTS

Adjusted creatinine clearance was higher in current smokers than in former smokers and never smokers (100.6 +/- 13.6 vs. 98.8 +/- 13.9 mL/min/1.73 m2, P < 0.0001, and vs. 98.5 +/- 14.0 mL/min/1. 73 m2, P < 0.0001, respectively). This difference was predominant in men and weak in women, and was associated with the number of cigarettes smoked daily. The slope of the projected age-related decline in the creatinine clearance accelerated with age, but it was similar in current smokers, former smokers, and never smokers. Creatinine clearance was associated with a relative risk of proteinuria [for each mL/min/1.73 m2, the relative risk was 1.007 (95% CI, 1.000 to 1.015), P = 0.056, for 1+ or higher proteinuria; and 1.018 (1.004 to 1.030), P = 0.0078, for 2+ or higher proteinuria]. Current and former smokers had a marked risk of 2 or higher proteinuria [adjusted RR (95% CI), 3.26 (1.66 to 6.80), P = 0. 0009, and 2.69 (1.24 to 5.99), respectively, P = 0.013, vs. never smoking], which was independent of the daily or cumulative cigarette consumption.

CONCLUSIONS

In the general population, smokers do not exhibit lower creatinine clearance than never smokers. In fact, creatinine clearance is slightly higher in current smokers at least in men, even when normotensive and hypertensive subjects are analyzed separately, but the difference is small, especially in women. This effect seems reversible upon smoking discontinuation. Chronic smoking results in a marked risk of irreversible proteinuria that may occur despite moderate smoking.

Proteinuria as a risk factor for cardiovascular disease and mortality in older people: a prospective study

BACKGROUND

The prognostic significance of proteinuria in older people is not well defined. We examined the associations between proteinuria and incident coronary heart disease, cardiovascular mortality, and all-cause mortality in older people.

SUBJECTS AND METHODS

Casual dipstick proteinuria was determined in 1,045 men (mean [+/- SD] age 68 +/- 7 years) and 1,541 women (mean age 69 +/- 7 years) attending the 15th biennial examination of the Framingham Heart Study. Participants were divided by grade of proteinuria: none (85.3%), trace (10.2%), and greater-than-trace (4.5%). Cox proportional hazards analyses were used to determine the relations of baseline proteinuria to the specified outcomes, adjusting for other risk factors, including serum creatinine level.

RESULTS

During 17 years of follow-up, there were 455 coronary heart disease events, 412 cardiovascular disease deaths, and 1,214 deaths. In men, baseline proteinuria was associated with all-cause mortality (hazards ratio [HR] = 1.3, 95% confidence interval [CI] 1.0 to 1.7 for trace proteinuria; HR = 1.3, 95% CI 1.0 to 1.8 for greater-than-trace proteinuria; P for trend = 0.02). In women, trace proteinuria was associated with cardiovascular disease death (HR = 1. 6, 95% CI 1.1 to 2.4), and all-cause mortality (HR = 1.4, 95% CI 1.1 to 1.7).

CONCLUSION

Proteinuria is a significant, although relatively weak, risk factor for all-cause mortality in men and women, and for cardiovascular disease mortality in women.

Hyperinsulinemia and abdominal obesity are more prevalent in non-diabetic subjects with family history of type 2 diabetes

BACKGROUND

This study was undertaken in order to identify the relationships between family history of type 2 diabetes and cardiovascular risk factors in non-diabetic Mexican individuals.

METHODS

The design was a cross-sectional, population-based study stratified by age and sex. Participants consisted of 189 non-diabetic volunteers 30-64 years of age, both males and non-pregnant females randomly selected from a middle income neighborhood in Durango, Mexico and distributed into two groups, with and without family history of type 2 diabetes mellitus. Hypertensive subjects were excluded. Body mass index (BMI) and waist-to-hip ratio (WHR) were assessed. Hematocrit, both fasting and 2-h post 75-g glucose load insulin, and glucose levels, lipid profile, serum albumin, and proteinuria were measured.

RESULTS

Ninety-four (49.7%) individuals with family history of type 2 diabetes, and 95 (50.3%) in the control group were included. The prevalence of obesity was greater among women with family history of diabetes, 39 (73.6%) vs. 27 (50.0%) of the control group, p = 0.02. Adiposity tended to be centrally distributed in 86 subjects, of whom 22 (25. 6%) males and 54 (62.8%) females were in the group with family history of diabetes and four (4.6%) males and six (7.0%) females in the control group, p <0.000. Multivariate logistic regression analysis showed a strong relationship between family history of type 2 diabetes with both abdominal obesity (odds ratio [OR] 4.2, CI 95% 1.9-10.1, p <0.05) and fasting hyperinsulinemia (OR 3.1, CI 95% 1. 4-11.2, p <0.05).

CONCLUSION

In the absence of additional risk factors such as diabetes and hypertension, there is a strong relationship between family history of diabetes with hyperinsulinemia and abdominal obesity in middle-aged Mexican individuals.

Evaluation and management of proteinuria and nephrotic syndrome in children: recommendations from a pediatric nephrology panel established at the National Kidney Foundation conference on proteinuria, albuminuria, risk, assessment, detection, and elimination (PARADE)

OBJECTIVE

The development of this review article evolved from a National Kidney Foundation consensus conference on recent advances in the importance of evaluating and treating proteinuria. From this conference, a series of recommendations for the evaluation of adults with proteinuria was published. Because specific pediatric aspects of the problem were outside the scope of the original National Kidney Foundation publication, an ad hoc committee of 6 pediatric nephrologists who were active participants in the National Kidney Foundation conference was established to provide primary care physicians with a concise, up-to-date reference on this subject.

METHODS

The recommendations that are given represent the consensus opinions of the authors. These are based on data from controlled studies in children when available, but many of the opinions are, by necessity, based on uncontrolled series in children or controlled trials performed in adults, because controlled trials in children have not been performed to evaluate many of the treatments described.

RESULTS AND CONCLUSIONS

These recommendations are intended to provide primary care physicians with a useful reference when they are faced with a young child or teenager who presents with proteinuria, whether this is mild and asymptomatic or more severe, leading to nephrotic syndrome.

Proteinuria: its clinical importance and role in progressive renal disease

In patients with essential hypertension and in those with diabetes mellitus, the presence of increased amounts of urinary protein or albumin has been shown to be an important and independent risk for an increased incidence of cardiovascular morbidity and mortality. A constellation of cardiovascular risk factors has been described in these individuals, as well as evidence for diffuse endothelial cell dysfunction, which suggests these individuals are particularly susceptible to the development of extensive vascular disease. Recent studies have also suggested that proteinuria is not only a marker for renal disease but it also predicts those patients at greatest risk for the development of chronic and progressive renal insufficiency. This effect of proteinuria was evident in patients in whom urinary protein excretion rates exceeded 1 g/24 hours, but probably is true even in patients with smaller amounts of proteinuria. This effect of proteinuria on progression of renal disease is independent of other risk factors such as level of renal function, blood pressure, and dyslipidemia. Recent clinical studies have demonstrated that modification of proteinuria by the use of angiotensin-converting enzyme (ACE) inhibitors independent of reductions in systemic blood pressure results in slowing of the rate of loss of renal function and even stabilization of renal function over longer periods of treatment. In patients with renal disease, the totality of evidence suggests that multiple pharmacological and dietary modifications will be necessary to achieve the optimal slowing of the progression of renal disease. In addition, strategies will be required to reduce risks involved in the development of cardiovascular disease to ensure optimal patient survival. The similarity of risk factors involved in cardio-renal disease progression should allow us to achieve this goal with our current therapeutic armamentarium.

Persistent improvement of cardiovascular risk factors in spontaneously hypertensive rats following early short-term captopril treatment

This study was designed to determine whether an improvement in cardiovascular risk factors persists in spontaneously hypertensive rats (SHR) following withdrawal of angiotensin converting enzyme inhibitor (ACE-I) treatment. SHR were given deionized drinking water or captopril solution from four to sixteen weeks of age. At twelve weeks of age, rats from each group were instrumented with radiotelemetry devices for continuous monitoring of blood pressure. Mean arterial blood pressure was significantly lower in captopril-treated SHR during treatment (92+/-2 vs 147+/-1 mm Hg), and at twelve weeks after treatment withdrawal (131+/-2 vs 158+/-2 mm Hg). In addition, proteinuria, renal vascular resistance, plasma triglyceride levels, fasting glucose levels, post-prandial insulin levels, and heart weights were significantly reduced in the treated SHR compared to control SHR, at time-points between three to seven months after captopril withdrawal. Our findings indicate that short-term administration of an ACE-I during the developmental phase of hypertension in the SHR results in a long-term overall improvement of cardiovascular risk factors.

Microalbuminuria in essential hypertension: significance, pathophysiology, and therapeutic implications

Some patients with essential hypertension manifest greater than normal urinary albumin excretion (UAE). The significance of this association, which is the object of this review, is not well established. Hypertensive patients with microalbuminuria manifest greater levels of blood pressure, particularly at night, and higher serum levels of cholesterol, triglycerides, and uric acid than patients with normal UAE. Levels of high-density lipoprotein cholesterol, on the other hand, were lower in patients with microalbuminuria than in those with normal UAE. Patients with microalbuminuria manifested greater incidence of insulin resistance and thicker carotid arteries than patients with normal UAE. After a follow-up of 7 years, we observed that 12 cardiovascular events occurred among 54 (21.3%) patients with microalbuminuria and only two such events among 87 patients with normal UAE (P < 0.0002). Stepwise logistic regression analysis showed that UAE, cholesterol level, and diastolic blood pressure were independent predictors of the cardiovascular outcome. Rate of creatinine clearance from patients with microalbuminuria decreased more than that from those with normal UAE. In conclusion, these studies suggest that hypertensive individuals with microalbuminuria manifest a variety of biochemical and hormonal derangements with pathogenic potential, which results in hypertensive patients having a greater incidence of cardiovascular events and a greater decline in renal function than patients with normal UAE.

Proteinuria is an independent risk factor for ischemic stroke in non-insulin-dependent diabetes mellitus

BACKGROUND AND PURPOSE

Proteinuria is an independent risk factor for cardiovascular disease in patients with NIDDM. The aim of this study was to assess the relationship between proteinuria and ischemic stroke in subjects with NIDDM, and to determine whether proteinuria is an independent risk factor for stroke.

METHODS

We performed a case-control study of 59 diabetic patients with first-ever ischemic stroke due to thrombotic arterial occlusion, who were considered cases, and 180 diabetic patients without stroke, matched by gender, age, and diabetes duration, as a control group. WHO criteria for verified definite or possible stroke were used to ascertain the diagnosis of stroke. For the purpose of this study proteinuria was defined as a 24-hour urinary protein excretion rate of >/=20 and <200 microg/min. Risk factors included were smoking, blood pressure, body mass index, serum total cholesterol, hyperglycemia, and proteinuria.

RESULTS

Subjects with stroke had higher proteinuria proportion and systolic and diastolic blood pressures. Both frequency of antihypertensive treatment and antihypertensive drugs used were similar among subjects with and without stroke. In multivariate logistic regression analysis, the ORs and 95% CIs for the variables identified as risk factors for stroke were as follows: systolic pressure (OR 3.10; 95% CI 3.01 to 4.21; P=0.03); diastolic pressure (OR 3.30; 95% CI 1.04 to 4.48; P<0.0001); fasting glucose >/=11.1 mmol (OR 1.82; 905% CI 1.4 to 3.8; P=0.04), HbA1c >/=9.5% (OR 1.7; 95% CI 1.3 to 5.1; P<0.01), and proteinuria (OR 3.23; 95% CI 1.06 to 4.36; P<0.0001).

CONCLUSIONS

Our case-control study gives evidence that proteinuria is an independent risk factor for ischemic stroke in patients with NIDDM.

Left ventricular mass and microalbuminuria: relation to ambulatory blood pressure. Hypertension Diagnostic Service Investigators

1. Both microalbuminuria and left ventricular hypertrophy may reflect target organ damage in essential hypertension. Both are related to the prevailing level of blood pressure and both are associated with an increase in morbidity and mortality. 2. The database of the Hypertension Diagnostic Service, a multicentre secondary referral clinic for patients with essential hypertension, was analysed in order to clarify the level of association between microalbuminuria and left ventricular hypertrophy, which might explain the observed increase in morbidity and mortality in patients with microalbuminuria. Microalbuminuria was measured semiquantitatively by urine dip-stix. After the exclusion of patients with potential secondary hypertension, renal disease and diabetes mellitus, patients with complete data for microalbuminuria, left ventricular mass (LVM) and 24 h blood pressure monitoring were selected. 3. Data were complete for 704 patients (47% male, age 51 +/- 12 years) and 42% tested positive for microalbuminuria. Microalbuminuria was positively related to 24 h systolic blood pressure and weight and was negatively related to age. Left ventricular mass was higher in patients with microalbuminuria (men, 265 +/- 69 g; women, 207 +/- 61 g) than in those without (men, 250 +/- 64 g, P < 0.05; women, 185 +/- 50 g, P < 0.001). After correction for the effects of gender, body mass index and 24 h systolic blood pressure, the presence of microalbuminuria was associated with an increase in LVM of 10 g (P < 0.05, 95% confidence interval, 2-19 g).

Renal surrogates in essential hypertension

The kidney can be considered both as culprit and victim in the hypertensive process. Renal functional derangement contributes to the development of arterial hypertension and the development of secondary vascular damage both at the glomerular and arteriolar level accounts for the development of progressive nephrosclerosis. The most common alteration of renal function observed in humans since the early stages of essential hypertension is the presence of renal vasoconstriction. This can be accompanied by the appearance of hyperuricemia, increased urinary excretion of enzymes such as N-acetyl-beta- glucosaminidase and of proteins like albumin and beta2-microglobulin. Later on, a progressive fall in glomerular filtration rate accompanied or not by proteinuria can be observed if high blood pressure persists.

Biochemical and inflammatory changes in the exercising claudicant

Intermittent claudication is an early manifestation of atherosclerosis in the leg. The prognosis for the claudicating limb is reasonably good, but patients have excess cardiovascular morbidity and mortality rates compared with a control population. Increasing evidence suggests that the calf pain experienced when walking followed by rest generates a low-grade inflammatory response. The cumulative effects of these individual events may have an adverse effect on the progression of atherosclerosis. A review of the literature was performed to identify studies measuring the exercise-induced inflammatory response in claudicants and to try to identify the role of cumulative inflammatory changes in the progression of atherosclerosis. The effect of exercise training on these markers is briefly explored. Walking until the onset of calf pain (ischaemia) followed by rest (reperfusion) results in the generation of oxygen-derived free radicals, neutrophil activation and a generalized increase in vascular permeability. Baseline levels of chronic inflammatory markers such as acute-phase proteins are elevated in claudicants compared with controls, suggesting that the transient acute inflammatory response has longer-term consequences. Therapeutic exercise training appears to lead to an attenuation of these inflammatory markers. Intermittent claudication can be considered as part of an inflammatory disease process. However, the concerns that exercise training might potentiate the vascular inflammatory response appear to be unjustified, although further work is needed to clarify this. Exercise training should therefore be considered as an important treatment option for claudication.

Circadian variation of urinary microalbumin excretion and ambulatory blood pressure in patients with essential hypertension

OBJECTIVE

To investigate the relationship between circadian changes in urinary microalbumin excretion (UAE), blood pressure (BP) and physical activity in patients with essential hypertension.

DESIGN AND METHODS

The subjects were 45 patients with essential hypertension (EH group: 26 male and 19 female, age 56+/-12 years (mean +/- SD)) and 25 patients with diabetes mellitus (DM group: 14 male and 11 female, age 61+/-10 years). Their BP and physical activity (acceleration) were measured at 30-min intervals for 24 h by means of a multi-biomedical recorder (TM2425). Urine samples were collected during each of four 4-h daytime periods and one 8-h night-time period. From these samples, per-h UAE (UAE/h) was measured. Mean values for mean blood pressure (MBP) and acceleration were calculated for corresponding time periods. Plasma hormones were measured during an early morning rest period.

RESULTS

In the EH group, a significant positive correlation was observed between circadian variation of UAE/h and MBP in 35 (78%) subjects, and the mean coefficient of correlation (r) was 0.86+/-0.12. A significant positive correlation was observed between circadian variation of UAE/h and mean acceleration value (Gh) in 25 (56%) subjects, and the mean r value was 0.70+/-0.26. Multivariate linear regression analysis showed that MBP exerted a greater influence on UAE/h than Gh. Significant positive correlations were observed between UAE/day and plasma human atrial natriuretic peptide and plasma aldosterone concentration (r = 0.50, P < 0.01; r = 0.36, P< 0.05). None of these relations, however, was observed in the DM group.

CONCLUSIONS

In patients with essential hypertension, circadian changes in activity and variation of BP influence UAE/h, but no definite relationship of this kind was observed in patients with diabetes mellitus. Measurement of circadian changes in UAE or UAE/day may be useful in estimating the degree of daily stress in non-diabetic patients with essential hypertension.

Angiotensin II, nitric oxide, and end-organ damage in hypertension

The adaptive changes that accompany hypertension and involve the kidney, heart, and vessels, namely, muscle hypertrophy/hyperplasia, endothelial dysfunction and extracellular matrix increase can, in fact, be maladaptive and eventually lead to end-organ disease, such as renal failure, heart failure, and coronary disease. However, these changes vary markedly between individuals with similar levels of hypertension. Nitric oxide (NO), an endogenous vasodilator and inhibitor of vascular smooth muscle and mesangial cell growth, is synthesized in the endothelium by a constitutive NO synthase (NOS). NO antagonizes the effects of angiotensin II on vascular tone and growth and also down-regulates the synthesis of angiotensin converting enzyme (ACE) and angiotensin II type 1 (AT-1) receptors. In hypertension, the physiologic response to the increased shear stress and cyclic strain is to upregulate NOS activity in endothelial cells. Upregulation of vascular NOS activity is a homeostatic adaptation to the increased hemodynamic workload that may help in preventing end-organ damage. Indeed, hypertension-prone salt-sensitive rats manifest a decrease (instead of an increase) in vascular NOS activity when hypertensive; these rats develop severe vascular hypertrophy, left ventricular hypertrophy, and renal injury. Studies in hypertensive humans suggest that, independent of the effects of salt on blood pressure, salt sensitivity may be a marker for susceptibility to the development of endothelial dysfunction as well as cardiovascular and renal injury. We hypothesize that in hypertension, recognition of markers of cardiovascular susceptibility to injury and the understanding of the pathophysiological mechanisms involved may open new opportunities for therapeutic intervention. In this context, only those antihypertensive agents that lower blood pressure and concomitantly restore the homeostatic balance of vasoactive agents such as angiotensin II and NO within the vessel wall would be effective in preventing or arresting end-organ disease.

American Indian heritage and risk factors for renal injury

BACKGROUND

Little is known about the causes and consequences of renal disease among American Indians in the Great Lakes region of the United States.

METHODS

We examined clinical correlates of albumin/creatinine ratios among 1368 participants in the three tribal communities of the Inter-Tribal Heart Project using univariate and multivariate analysis.

RESULTS

Compared to 1086 participants without albuminuria, the 240 with microalbuminuria (30 to 299 mg/g) and the 42 with macroalbuminuria (>300 mg/g) were more likely to report a history of a myocardial infarction (6.4%, 16.0%, and 23.8%, respectively, P < 0.001). Similarly, compared to patients without albuminuria, those with microalbuminuria and macroalbuminuria were more likely to report a history of stroke (2.3%, 8.4% and 26.2%, respectively, P < 0.001). In a multiple linear regression model, independent correlates of albumin excretion (P < 0.05) included: fasting blood sugar, treated diabetes, treated hypertension, higher systolic blood pressure, lower diastolic blood pressure, abnormal electrocardiogram, a history of stroke, the degree of American Indian heritage, and lower household income.

CONCLUSIONS

Urinary albumin excretion is associated with cardiovascular disease outcomes and risk factors among American Indians of the Great Lakes region. Both heredity and socioeconomic status appear to play a role in the pathogenesis of renal injury in this population.

The Valsartan Antihypertensive Long-term Use Evaluation (VALUE) trial of cardiovascular events in hypertension. Rationale and design

Essential hypertension is a major Public Health issue. Although the number of treated hypertensive patients has increased, only 25% of treated patients have their blood pressure levels under control. The benefit of treating hypertension has been proven, but cardiovascular morbidity and mortality rates remain high. The ideal antihypertensive drug should not only normalize blood pressure levels, but also reduce the associated cardiovascular morbidity and mortality rates. The role of angiotensin II in systemic hypertension and its complications has been recently redefined. The potent trophic effects of angiotensin II on blood vessels and on cardiac cells have been well demonstrated, especially the role of angiotensin II in left ventricular hypertrophy, vascular hypertrophy, endothelial dysfunction, and congestive heart failure. Of all ongoing mortality and morbidity trials in systemic hypertension, VALUE (Valsartan Antihypertensive Long-term Use Evaluation) is the only one comparing an angiotensin II antagonist (valsartan) with a third-generation calcium channel blocker (amlodipine). The main hypothesis of the VALUE trial is that, for an equivalent decrease in blood pressure, valsartan will be more effective than amlodipine in decreasing cardiac mortality and morbidity. VALUE is a prospective, multinational, multicentre, double-blind, randomized, active-controlled, 2-arm parallel group comparison with a response-dependent dose titration scheme. VALUE involves 14,400 patients in over 30 countries, who will be followed for 4 years or until 1450 patients experience a primary endpoint. The population to be included in VALUE consists of hypertensive men and women, aged 50 years or older, and at a relatively high risk of sustaining a cardiovascular event. The high risk profile is defined taking into account age, gender, and a list of cardiovascular risk factors and disease factors. Risk factors are cigarette smoking, hypercholesterolaemia, diabetes mellitus, uncomplicated left ventricular hypertrophy, proteinuria, and high serum creatinine. Disease factors include documented history of myocardial infarction, peripheral vascular disease, stroke or transient ischaemic attack, or the presence of left ventricular hypertrophy with strain on the ECG. A unique feature of VALUE is the assessment of the predictive power of this cardiovascular risk factor scale in a large population of treated hypertensive patients. The trial started on 10 September 1997.

A randomized trial of captopril for microalbuminuria in normotensive adults with sickle cell anemia

PURPOSE

Nephropathy is a common complication of sickle cell anemia and is often preceded by proteinurea. Our aim was to evaluate the effect of angiotensin-converting enzyme inhibition on microalbuminuria in sickle cell patients.

PATIENTS AND METHODS

We performed a randomized, double-blind, placebo-controlled trial in 22 normotensive patients with sickle cell anemia and persistent microalbuminuria. Patients received captopril (25 mg/day) or placebo and were followed up for 6 months. Albuminuria, blood pressure, and serum creatinine and hemoglobin concentrations were measured at baseline and at 1, 3, and 6 months. The primary outcome variable was the 6-month change in albuminuria between the two groups.

RESULTS

Baseline albuminuria was 121 (SD 66) mg per 24 hours in the captopril group and 107 (SD 86) mg per 24 hours in the placebo group. Microalbuminuria decreased from baseline in the captopril group but increased in the placebo group. The mean absolute change and the mean percentage change in microalbuminuria were significantly different between the two groups at 6 months (absolute change -45 mg per 24 hours in the captopril group versus +18 mg per 24 hours in the placebo group, P <0.01; and percentage change -37% in the captopril group versus +17% in the placebo group, P <0.01). The 95% confidence intervals (CI) for the difference in albuminuria between the two groups were 63 (CI 40 to 86) mg per 24 hours for the mean absolute change and 54% (CI 22% to 85%) for the mean percentage change. Blood pressure decreased slightly from baseline in captopril-treated patients and did not change in the placebo group. The change was significantly different between the two groups only for diastolic blood pressure at 6 months (P <0.01).

CONCLUSION

Captopril reduces albuminuria and slightly decreases blood pressure in patients with sickle cell anemia. More studies are required to demonstrate the sustained benefit on protein excretion.

The evidence for exercise-induced inflammation in intermittent claudication: should we encourage patients to stop walking?

OBJECTIVES

To review clinical and experimental evidence that exercise to the onset of calf pain in patients with intermittent claudication results in an inflammatory response, and to consider whether repeated inflammatory events induced by therapeutic exercise training may lead to progression of atherosclerosis.

METHODS

A literature search was performed to identify studies measuring biochemical markers of exercise-induced ischaemia-reperfusion injury in patients with intermittent claudication. Current theories of atherogenesis were reviewed and the use of acute-phase proteins as potential markers of vascular disease explored.

RESULTS

Exercise to the onset of calf pain results in an inflammatory response with free radical formation, neutrophil activation and systemic vascular endothelial damage. Acute-phase proteins such as C-reactive protein and serum amyloid A protein have exciting potential use as stable biochemical markers of disease in claudication.

CONCLUSIONS

Further studies are needed to determine the effect of long-term exercise training on exercise-induced inflammation in claudication. Early work suggests, in fact, that exercise attenuates this inflammatory response. If this were confirmed then it would support the clinical impression that exercise training is beneficial in terms of symptomatic improvement and cardiovascular health in patients with intermittent claudication.

Nitric oxide in hypertension: relationship with renal injury and left ventricular hypertrophy

Hypertension is accompanied by architectural changes in the kidney, heart, and vessels that are often maladaptive and can eventually contribute to end-organ disease such as renal failure, heart failure, and coronary disease. Nitric oxide, an endogenous vasodilator and antithrombotic agent synthesized in the endothelium by a constitutive nitric oxide synthase, inhibits growth-related responses to injury in vascular cells. Specifically, in the presence of hypertension, nitric oxide may work in the kidney by inhibiting both mesangial cell hypertrophy and hyperplasia as well as synthesis of extracellular matrix and in the heart and systemic vessels by modulating smooth muscle cell hypertrophy and hyperplasia. The effects of nitric oxide are antagonistic of the effects of angiotensin II. Shear stress and cyclic strain, physical forces known to operate in hypertension, are accompanied by increases in endothelial nitric oxide synthase expression, nitric oxide synthase protein, and nitric oxide synthase activity in endothelial cells. Experimental studies using genetic models of hypertension show a variation in hypertension-modulated vascular nitric oxide synthase activity in different strains of rats. These studies suggest that upregulation of vascular nitric oxide synthase activity is a homeostatic adaptation to increased hemodynamic workload in hypertension and that this may help prevent end-organ damage. If these findings apply to humans, differences in end-organ disease seen in patients with similar degrees of hypertension may be due in part to genetic differences in vascular nitric oxide synthase activity in response to hypertension.

Usefulness of microalbuminuria in predicting cardiovascular mortality in treated hypertensive men with and without diabetes mellitus. Risk Factor Intervention Study Group

In the present study we report on the predictive power of microalbuminuria for total and cardiovascular mortality in a prospective study (mean follow up 6.3 years) of treated hypertensive men, aged 50 to 72 years, with (n = 94) and without (n = 345) maturity onset diabetes mellitus. Thirty-three (35.1%) of the hypertensive patients with diabetes mellitus died during the follow-up period compared with 57 patients (16.5%) in the hypertensive group without diabetes mellitus (p <0.0002). In those with diabetes mellitus and hypertension, a log-rank test revealed a lower cardiovascular mortality in the normoalbuminuric group compared with both the microalbuminuric (p = 0.035) and the macroalbuminuric group (p = 0.002). The logarithm of urinary albumin excretion was a predictor of both total (p = 0.009) and cardiovascular (p = 0.001) mortality during the follow-up period using Cox regression analysis. This relation remained significant even after adjustment for other risk factors. HbA1c was also an independent predictor of total and cardiovascular mortality. In patients without diabetes mellitus, the small group of patients with macroalbuminuria had a markedly increased cardiovascular mortality compared with both the microalbuminuric (p <0.0001) and the normoalbuminuric groups (p <0.0001). No difference was observed between the normoalbuminuric and the microalbuminuric groups. Smoking at entry and concomitant cardiovascular disease at entry were independent predictors of cardiovascular mortality in these patients. We conclude that microalbuminuria was an independent predictor for cardiovascular mortality in treated hypertensive men with maturity onset diabetes mellitus. Macroalbuminuria, but not microalbuminuria, predicted cardiovascular mortality in nondiabetic treated hypertensive men.

Risk factors of end-stage renal disease and serum creatinine in a community-based mass screening

This study evaluated risk factors for end-stage renal disease (ESRD) and the prognostic significance of serum creatinine levels in a community-based mass screening. We used the registries of both community-based mass screening and chronic dialysis programs. In 1983, a total of 107,192 subjects over 18 years of age (51,122 men and 56,070 women) participated in a mass-screening program in Okinawa, Japan. Among them, serum creatinine data were available for 14,609 participants (5,613 men and 8,996 women). During 10 years of follow-up, we identified 60 dialysis patients (29 men and 31 women) among this group. Logistic regression analysis on the risk of ESRD was performed to determine the significance of serum creatinine levels in comparison with other clinical variables. The adjusted odds ratio (95% confidence interval) was 5.31 (3.39 to 8.32) in men and 3.92 (2.88 to 5.34) in women when compared to baseline serum creatinine levels of less than 1.0 mg/dl in women and 1.2 mg/dl in men. Diastolic blood pressure was not a significant predictor of ESRD. Results demonstrated the prognostic significance of serum creatinine in a community-based mass screening. Gender difference in the incidence of ESRD was explained, at least partly, by differences between clinical predictors and baseline serum creatinine levels.

ACE inhibitors and proteinuria

This review discusses the clinical consequences of urinary protein loss and the effects of inhibitors of the angiotensin converting enzyme (ACE) on this clinical finding. Proteinuria appears to be an important risk factor for renal function deterioration and for cardiovascular mortality. ACE inhibitors have been shown to reduce proteinuria more effectively than other antihypertensives. Their antiproteinuric effect seems to be independent of the underlying renal disease, and is mediated by a specific, not yet fully elucidated mechanism. Urinary protein loss related phenomena, such as hypoalbuminemia and aberrant lipoprotein profile, tend to improve also during ACE inhibitor treatment. Furthermore, ACE inhibition has been shown to prevent the renal function deterioration that is frequently observed in patients with renal disease. Interestingly, it has recently been shown that in proteinuric patients with renal disease the initial proteinuria lowering response to ACE inhibition predicts long-term renal function outcome during this treatment the more proteinuna is lowered during the first months, the better renal function will be preserved over the following years. Because of these favorable effects ACE inhibitors have become a widely used class of agents in nephrology. They are not only prescribed for lowering blood pressure in the hypertensive renal patient, but also as symptomatic treatment of patients with proteinuria, and to prevent renal function loss in patients with both diabetic and non-diabetic renal disease.

Effect of ramipril on blood pressure and protein excretion rate in normotensive nondiabetic patients with proteinuria

Angiotensin-converting enzyme inhibitors reduce proteinuria in both normotensive and hypertensive patients with proteinuric renal disease. However, the mechanism of the antiproteinuric effect has not been clarified. We performed a prospective, double-blind, placebo-controlled, randomized crossover trial to test the hypothesis that the antiproteinuric effect of ramipril was due to an improvement in glomerular permselectivity independent of blood pressure and glomerular filtration rate. The effect of low-dose (1.25 mg/d) and high-dose (5 mg/d) ramipril was assessed in 15 normotensive nondiabetic patients with proteinuria (> 150 mg/d). The study was divided into four 12-week periods: placebo, high- or low-dose ramipril, crossover to low- or high-dose ramipril, and placebo. Blood pressure, glomerular filtration rate, renal plasma flow rate, urinary protein excretion rate, and plasma angiotensin II levels were measured at the end of each period. Mean arterial pressure, urine protein to creatinine ratio, and albumin excretion rate decreased significantly during low- and high-dose ramipril. Glomerular filtration rate and renal plasma flow rate were not changed significantly. Plasma angiotensin II levels decreased with both low- and high-dose ramipril. There were no episodes of hypotension and only one subject developed cough during ramipril that did not require discontinuation of the study drug. In conclusion, administration of ramipril in both low and high doses lowered blood pressure and reduced proteinuria in this cohort of normotensive patients with a variety of proteinuric renal diseases. The antiproteinuric effect of ramipril is probably mediated by a reduction in glomerular capillary pressure.

Proteinuria predicts stroke and other atherosclerotic vascular disease events in nondiabetic and non-insulin-dependent diabetic subjects

BACKGROUND AND PURPOSE

Increased urinary albumin and protein excretion is associated with cardiovascular disease mortality independent of other cardiovascular risk factors in subjects with non-insulin-dependent diabetes mellitus (NIDDM). We assessed the relationship between the different degrees of proteinuria at baseline and the incidence of stroke, as well as other atherosclerotic vascular disease events, in a prospective study of nondiabetic and NIDDM subjects.

METHODS

Our study was based on the 7-year follow-up of cohorts of nondiabetic (n = 1375) and NIDDM (n = 1056) subjects in Finland. The urinary protein concentration at baseline was stratified into three categories: no proteinuria (< 150 mg/L), borderline (150 to 300 mg/L), and clinical proteinuria (> 300 mg/L).

RESULTS

The association between the different degrees of proteinuria and the atherosclerotic vascular events was similar in nondiabetic and NIDDM subjects. Cardiovascular disease mortality was higher both in nondiabetic and NIDDM subjects with clinical proteinuria than in those without proteinuria. The incidence of stroke was 1.6% in nondiabetic subjects without proteinuria, 3.2% in subjects with borderline proteinuria, and 8.5% in subjects with clinical proteinuria (P < .001 for trend). In NIDDM patients, the corresponding rates were 7.2%, 11.1%, and 23.0%, respectively (P < .001 for trend). The association between clinical proteinuria and the incidence of stroke remained significant both in nondiabetic and in NIDDM subjects after adjustment for other cardiovascular risk factors. Clinical proteinuria was also associated with the incidence of coronary heart disease events and that of lower-extremity amputation. NIDDM independently increased the risk of atherosclerotic vascular disease events regardless of the proteinuria status.

CONCLUSIONS

Clinical proteinuria significantly predicted stroke and other atherosclerotic vascular disease events independent of other cardiovascular risk factors. This finding is compatible with the view that increased urinary protein excretion rate may be associated with widespread vascular damage.

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

The aim of this prospective study was to investigate the risk factors for development of microalbuminuria in treated hypertensive men with and without diabetes mellitus. Two hundred and ninety-seven treated hypertensive men, aged fifty to seventy-two years, with at least one of the following: serum cholesterol > or = 6.5 mmol/L, smoking, or diabetes mellitus, were included in the study. Patients with elevated overnight urinary albumin excretion (> 17 mg/12 hr) were excluded. Urinary albumin excretion (UAE), blood pressure, and various well-established risk factor levels were measured. Two hundred thirteen nondiabetic patients and 40 patients with diabetes mellitus completed the three-year follow-up. Development of microalbuminuria was more prevalent in those with diabetes mellitus at baseline compared with the group without diabetes mellitus, 25% and 10.3%, respectively (P = 0.02). Nondiabetic patients who developed microalbuminuria had higher UAE. 10.2 mg +/- 3.7 and 5.7 +/- 3.2, respectively (P < 0.0001), and higher systolic blood pressure 160 mm Hg +/- 27 and 152 +/- 17, respectively (P = 0.043), at baseline compared with whose who remained normoalbuminuric. In the group with diabetes mellitus, a higher UAE, 9.8 +/- 2.7 and 7.1 +/- 3.6, respectively (P = 0.036), at baseline was observed in whose who developed microalbuminuria compared with whose who remained normoalbuminuric. In conclusion, concomitant diabetes mellitus significantly increased the risk for development of microalbuminuria during the three-year follow-up in treated hypertensive men. Patients who progressed to microalbuminuria had higher UAE at baseline, but still within the normoalbuminuric range, compared with thosewho remained normoalbuminuric. Systolic blood pressure at baseline was higher in those who progressed to microalbuminuria, although reaching statistically significance only in the larger nondiabetic group.

Current drug treatment and treatment patterns with antihypertensive drugs

The 4 major classes of antihypertensive drugs are diuretics, beta-blockers, ACE inhibitors and calcium antagonists. The diuretics have recently regained prominence, largely due to the results of recent controlled trials. These trials in elderly patients demonstrated that low-dose diuretics were effective not only in preventing stroke but also in greatly reducing coronary-related events. Diuretics also decrease left ventricular mass more than the other major drug classes. In addition, they are the most effective drugs for use in combination therapy. By contrast, the safety of calcium antagonists has recently been questioned because of report of increased coronary morbidity and mortality. However, these adverse events may be restricted to the short-acting preparations, especially nifedipine, which causes cardiac stimulation. ACE inhibitors, like beta-blockers, are not only effective in reducing blood pressure, particularly when combined with a diuretic, but also improve angina and decrease postinfarction mortality. They also benefit congestive heart failure, stabilise or improve renal function in hypertensive and diabetic nephropathy and reduce albuminuria. Beta-Blockers are especially effective in reducing sudden cardiac death in patients with coronary heart disease, particularly in postinfarction patients. Final proof of the relative effectiveness of these drugs in preventing morbidity and mortality must await the outcome of large comparative trials currently under way. A recent national survey in the US found that more than 75% of hypertensive patients did not have their hypertension completely controlled. Possible reasons for this disturbing statistic are discussed along with suggestions for improvement.