Alcohol consumption and microvascular dysfunction: a J-shaped association: The Maastricht Study

BACKGROUND

Microvascular dysfunction (MVD) is an important contributor to major clinical disease such as stroke, dementia, depression, retinopathy, and chronic kidney disease. Alcohol consumption may be a determinant of MVD.

OBJECTIVE

Main objectives were (1) to study whether alcohol consumption was associated with MVD as assessed in the brain, retina, skin, kidney and in the blood; and (2) to investigate whether associations differed by history of cardiovascular disease or sex.

DESIGN

We used cross-sectional data from The Maastricht Study (N = 3,120 participants, 50.9% men, mean age 60 years, and 27.5% with type 2 diabetes [the latter oversampled by design]). We used regression analyses to study the association between total alcohol (per unit and in the categories, i.e. none, light, moderate, high) and MVD, where all measures of MVD were combined into a total MVD composite score (expressed in SD). We adjusted all associations for potential confounders; and tested for interaction by sex, and history of cardiovascular disease. Additionally we tested for interaction with glucose metabolism status.

RESULTS

The association between total alcohol consumption and MVD was non-linear, i.e. J-shaped. Moderate versus light total alcohol consumption was significantly associated with less MVD, after full adjustment (beta [95% confidence interval], -0.10 [-0.19; -0.01]). The shape of the curve differed with sex (P_interaction = 0.03), history of cardiovascular disease (P_interaction < 0.001), and glucose metabolism status (P_interaction = 0.02).

CONCLUSIONS

The present cross-sectional, population-based study found evidence that alcohol consumption may have an effect on MVD. Hence, although increasing alcohol consumption cannot be recommended as a policy, this study suggests that prevention of MVD may be possible through dietary interventions.

Microalbuminuria, cardiovascular risk factors and cardiovascular morbidity in a British population: The EPIC-Norfolk Population-based Study

BACKGROUND

Microalbuminuria is independently associated with increased cardiovascular risk and renal function deterioration in diabetes and hypertension, but the clinical relevance of raised albuminuria in the general population is less certain. We examined the prevalence of microalbuminuria and its relationship to cardiovascular risk factors and cardiovascular morbidity in the UK general population.

METHODS

Cross-sectional population-based study of 23,964 individuals, aged 40-79 years recruited in 1993-1997 for the EPIC-Norfolk Study. Smoking status, prevalent physician diagnosed diabetes, hypertension, cardiovascular disease and cancer were derived from a health and lifestyle questionnaire. Albumin-to-creatinine ratios were estimated from random spot urine specimens collected at the survey visit, and using these ratios participants were categorized into normoalbuminuria, microalbuminuria (2.5-25 mg/mmol), and macroalbuminuria.

RESULTS

The prevalence of microalbuminuria and macroalbuminuria was 11.8% and 0.9% respectively in the total population and significantly higher in women (14.4%) compared with men (8.9%) (P<0.001). Independent determinants of microalbuminuria were age, sex, systolic blood pressure and current smoking. Microalbuminuria was independently associated with cardiovascular morbidity, after adjusting for known cardiovascular risk factors, with odds ratio (95% confidence interval) for prevalent cardiovascular disease of 1.30 (1.12-1.51) in all men and women.

CONCLUSION

Microalbuminuria was present in approximately 12% of this population. It was independently associated with cardiovascular risk factors and prevalent cardiovascular disease. Microalbuminuria may be a useful indicator of high absolute cardiovascular risk in the community but prospective data are needed to establish its independent predictive value for future events.

Reversibility of albuminuria and continuous positive airway pressure compliance in patients of obstructive sleep apnea syndrome

A positive correlation between albuminuria and severity of obstructive sleep apnea syndrome (OSAS) has been demonstrated, as indexed by urine albumin-to-creatinine ratios (UACRs). However, the effect of continuous positive airway pressure (CPAP) treatment on albuminuria in OSAS patients has not been established.Sixty subjects, with apnea-hypopnea indices >15 events per hour and no other diagnoses associated with albuminuria, underwent overnight polysomnography for sleep apnea and were examined for UACR at baseline and after 6 months of CPAP therapy. CPAP compliance rates were also recorded.Significant improvement in UACR was found in OSAS patients with good compliance to CPAP treatment after 6 months of therapy (baseline vs 6-month follow-up, 32.0 ± 9.5 vs 19.2 ± 6.5 mg/g, respectively, P = 0.007), whereas slight worsening in UACRs was noted in patients with poor compliance to CPAP treatment (baseline vs 6-month follow-up, respectively, 16.7 ± 4.4 vs 19.1 ± 6.3 mg/g, respectively, P = 0.39). Change in UACR was significant between poor compliance versus good compliance groups (2.4 ± 2.7 vs -12.8 ± 4.4 mg/g, respectively, t = 2.9, P = 0.005). A significant correlation between improvement in UACR and CPAP compliance rates was also noted (Spearman's correlation coefficient: -0.37, P = 0.007). Baseline UACR, good CPAP compliance, and body mass index were independent predictors of changes in UACR.Adequate CPAP treatment improves albuminuria in OSAS patients. In addition to monitoring CPAP adherence and subjective sleepiness, UACR may offer an objective physiological index of CPAP therapeutic effectiveness.

Association between Salt Intake and Albuminuria in Normotensive and Hypertensive Individuals

Background. There is a little published data regarding the association between salt intake and albuminuria as an important alarm for progression of cardiovascular and renal dysfunction. We aimed to assess this relationship to emphasize the major role of restricting salt intake to minimize albuminuria and prevent these life-threatening events. Methods. The study population comprised 820 individuals. Participants were assigned to groups as follows: normal albuminuria, slight albuminuria, and clinical albuminuria. Daily salt intake was assessed on the basis of 24-hour urinary sodium excretion, since urinary sodium excretion largely equals sodium intake. Results. In normotensive participants, the mean level of urine albumin was higher in those who had higher amounts of salt intake with a significantly upward trend (the mean urinary albumin level in low-salt-diet group, in medium-salt-intake group, and in high-salt-intake group was 42.70 ± 36.42, 46.89 ± 38.91, and 53.38 ± 48.23, resp., (P = 0.017)). There was a significant positive correlation between 24-hour urinary sodium secretion and the level of urine albumin (beta = 0.130, P < 0.001). The amount of salt intake was significantly associated with urine albumin concentration (beta = 3.969, SE = 1.671, P = 0.018). Conclusion. High salt intake was shown to be associated with higher level of microalbuminuria even adjusted for potential underlying risk factors.

Bariatric surgery and renal function

Obesity causes a significant healthcare burden and has been shown to be an important risk factor in the development of cardiovascular disease, type 2 diabetes, and increasingly chronic kidney disease. Bariatric surgery is the most effective treatment for obesity and has been shown to drastically improve both blood pressure and diabetic control. However, the interaction of bariatric surgery and renal function is less clear. This review focuses on the effect of bariatric surgery on renal function both in the acute situation, with respect to acute kidney injury, and also on changes in renal function parameters post-bariatric surgery weight loss. The interaction of obesity, bariatric surgery, and nephrolithiasis as a precipitant of acute kidney injury will also be considered. The role of bariatric surgery in pre- and post-renal transplant recipients is discussed as well as possible mechanisms underlying the improvement in renal function.

Obesity-related cardiovascular risk factors after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention

OBJECTIVE

Weight reduction improves several obesity-related health conditions. We aimed to compare the effect of bariatric surgery and comprehensive lifestyle intervention on type 2 diabetes and obesity-related cardiovascular risk factors.

DESIGN

One-year controlled clinical trial (ClinicalTrials.gov identifier NCT00273104).

METHODS

Morbidly obese subjects (19-66 years, mean (s.d.) body mass index 45.1 kg/m(2) (5.6), 103 women) were treated with either Roux-en-Y gastric bypass surgery (n=80) or intensive lifestyle intervention at a rehabilitation centre (n=66). The dropout rate within both groups was 5%.

RESULTS

Among the 76 completers in the surgery group and the 63 completers in the lifestyle group, mean (s.d.) 1-year weight loss was 30% (8) and 8% (9) respectively. Beneficial effects on glucose metabolism, blood pressure, lipids and low-grade inflammation were observed in both groups. Remission rates of type 2 diabetes and hypertension were significantly higher in the surgery group than the lifestyle intervention group; 70 vs 33%, P=0.027, and 49 vs 23%, P=0.016. The improvements in glycaemic control and blood pressure were mediated by weight reduction. The surgery group experienced a significantly greater reduction in the prevalence of metabolic syndrome, albuminuria and electrocardiographic left ventricular hypertrophy than the lifestyle group. Gastrointestinal symptoms and symptomatic postprandial hypoglycaemia developed more frequently after gastric bypass surgery than after lifestyle intervention. There were no deaths.

CONCLUSIONS

Type 2 diabetes and obesity-related cardiovascular risk factors were improved after both treatment strategies. However, the improvements were greatest in those patients treated with gastric bypass surgery.

Off-pump surgery does not eliminate microalbuminuria or other markers of systemic inflammatory response to coronary artery bypass surgery

OBJECTIVE

To evaluate whether off-pump surgery attenuates microalbuminuria and other markers of systemic inflammatory response to coronary artery bypass surgery as compared to surgery performed using cardiopulmonary bypass.

DESIGN

Forty-three adult patients undergoing elective coronary artery bypass grafting surgery were operated on with or without cardiopulmonary bypass (CPB). Microalbuminuria, serum C-reactive protein, and oxygenation and lung function parameters were measured at several time points until the first postoperative morning.

RESULTS

The urinary albumin/creatinine ratio was low in both groups before surgery, but reached a maximum level at the end of CPB or just after opening the last coronary artery clamp in the off-pump group (p<0.05). The urinary albumin/creatinine ratio remained slightly elevated in both groups until the morning after the operation (p<0.05). There were no statistical differences between groups. Serum C-reactive protein remained at the initial level the evening after the operation, but increased by the first postoperative morning in both groups (p<0.001). The alveolar-arterial gradient for oxygen partial pressure rose significantly after the operation in the intensive care unit in both groups (p<0.0001). The shunt fraction of the pulmonary circulation did not change in either group.

CONCLUSIONS

Off-pump coronary artery surgery did not prevent the acute phase inflammatory response measured in the present study. The acute phase inflammatory response after coronary artery bypass surgery is more likely a response to the surgical trauma itself rather than to CPB.

Blood pressure, atherosclerosis, and albuminuria in 10,113 participants in the atherosclerosis risk in communities study

BACKGROUND

Albuminuria predicts cardiovascular risk, but its function as a marker of endothelial damage and atherosclerosis is uncertain, as is the complex relationship with hypertension and diabetes.

OBJECTIVE

To determine whether hypertension contributes to albuminuria across levels of atherosclerosis and type 2 diabetes.

METHODS

Cross-sectional associations of cardiovascular risk factors and albuminuria were examined in 10,113 middle-aged participants in the atherosclerosis risk in communities study divided into four subgroups: type 2 diabetes with marked atherosclerosis, type 2 diabetes without marked atherosclerosis, without diabetes with marked atherosclerosis, and without diabetes without marked atherosclerosis. Marked atherosclerosis was defined as high levels of carotid atherosclerosis or prevalent coronary heart disease.

RESULTS

Hyperglycemia and hypertriglyceridemia were associated with albuminuria, but only among patients with type 2 diabetes. In multivariate models, increasing blood pressure levels (but not albuminuria) were significantly associated (P-trend <0.001) with carotid atherosclerosis when stratified by prevalent coronary heart disease. Excluding individuals on hypertension medication, higher blood pressure was associated with albuminuria in all groups (P-trend<0.05). The association was strong even for high-normal blood pressure among individuals without diabetes without marked atherosclerosis (odds ratio 2.7, 95% confidence interval 1.6-4.6) and patients with type 2 diabetes with marked atherosclerosis (12.0, 1.3-108.2).

CONCLUSION

Blood pressure, even at high-normal levels, is consistently associated with albuminuria across categories of type 2 diabetes and atherosclerosis. Our results suggest that the effects of blood pressure on albuminuria are not solely mediated through generalized vascular damage, as represented by degree of atherosclerosis.

Anemia as a risk factor for chronic kidney disease

Chronic kidney disease (CKD) is an important and leading cause of end-stage renal disease (ESRD) and moreover, plays a role in the morbidity and mortality due to cardiovascular disease, infection, and cancer. Anemia develops during the early stages of CKD and is common in patients with ESRD. Anemia is an important cause of left ventricular hypertrophy and congestive heart failure. Correction of anemia by erthyropoiesis-stimulating agent (ESA) has been shown to improve survival in patients with congestive heart failure. Anemia is counted as one of the non-conventional risk factors associated with CKD. Hypoxia is one of the common mechanisms of CKD progression. Treatment by ESA is expected to improve quality of life, survival, and prevent the CKD progression. Several clinical studies have shown the beneficial effects of anemia correction on renal outcomes. However, recent prospective trials both in ESRD and in CKD stages 3 and 4 failed to confirm the beneficial effects of correcting anemia on survival. Similarly, treatment of other risk factors such as hyperlipidemia by statin showed no improvement in the survival of dialysis patients. Given the high prevalence of anemia in ESRD and untoward effects of anemia in CKD stages 3 and 4, appropriate and timely intervention on renal anemia using ESA is required for practicing nephrologists and others involved in the care of high-risk population. Lessons from the recent studies are to correct renal anemia (hemoglobin <10 g/dl not hemoglobin > or =13 g/dl). Early intervention for renal anemia is a part of the treatment option in the prevention clinic. In this study, clinical significance of anemia management in patients with CKD is discussed.

Obesity and kidney disease

The prevalence of obesity worldwide has increased dramatically. Besides, an approximately two-fold higher rate of increase in mean BMI among the incident ESRD has been reported in the US population from 1995-2002. Chronic kidney disease (CKD) prevalence increases from 2.9% among adults with an ideal BMI to 4.5% among obese adults. The development of CKD is usually the culminating result of the interaction of multiple risk factors. Obesity represents one example of a multitoxicity state and given the background of genetic susceptibility and/or reduced nephron number, overweight may initiate renal remodeling and/or accelerate kidney failure. Obesity may be the number one preventable risk factor for CKD. Weight loss has indeed been shown to improve glomerular hemodynamics and reduce urine albumin excretion. Thus, obese patients with CKD should be counseled on the benefits of weight loss.

Central obesity is an independent risk factor for albuminuria in nondiabetic South Asian subjects

OBJECTIVE

South Asians have a high prevalence of central obesity. When the diagnosis of diabetes is made, they have a very high risk of developing renal failure. In the current study, we explored the hypothesis that central obesity is associated with the development of renal injury, before the manifestation of diabetes.

RESEARCH DESIGN AND METHODS

We invited first-degree nondiabetic relatives of South Asian type 2 diabetic patients for investigation of microalbuminuria and diabetes. Subjects who used antihypertensive or antidiabetic medication were excluded. We performed a glucose tolerance test according to the classic World Health Organization criteria. A total of 205 subjects were normoglycemic; we excluded 25 subjects because of impaired glucose tolerance, and 30 subjects were excluded because of de novo diabetes. Central obesity was measured by waist-to-hip ratio (WHR). Albuminuria was measured as albumin-to-creatinine ratio (ACR) in the early-morning urine.

RESULTS

Central obesity was independently related with albuminuria in the 205 normoglycemic subjects. We found no relation of fasting blood glucose or systolic blood pressure with albuminuria. Multivariate analysis for the presence of increased albuminuria (median ACR >0.31 mg/mmol) showed a relative risk of 4.1 for the highest versus the lowest tertile of WHR (P = 0.002).

CONCLUSIONS

Central obesity is an early and independent risk factor for increased albuminuria in normoglycemic South Asian subjects. This could explain the high incidence of diabetic renal disease in South Asians, probably by the mechanism of insulin resistance and endothelial dysfunction in the pre-diabetic state.

Diabetic nephropathy in the elderly

Renal impairment is frequent in aged diabetic patients, notably with type 2 diabetes. It results from a multifactorial pathogeny, particularly the combined actions of hyperglycaemia, arterial hypertension and ageing. Diabetic nephropathy (DN) is associated with an increased cardiovascular mortality. DN often leads to end stage renal failure (ESRF) which causes specific problems of decision and practical organization of extra-renal epuration in diabetic and aged patients. In the absence of renal biopsy, clinical signs are often insufficient to assess the diabetic origin of a nephropathy in an elderly diabetic patient. Prevention of DN is principally based on tight glycaemic and blood pressure control. The progression of renal lesions can be retarded by strict blood pressure control, notably by blocking of the renin-angiotensin system, if well tolerated in aged patients. It is absolutely necessary to avoid the worsening of renal lesions by potentially nephrotoxic products, notably non steroidal anti-inflammatory drugs (NSAIDs) and iodinated contrast media. At the stage of renal failure, it is important to adapt the antidiabetic treatment, and in the majority of the cases, to switch to insulin when glomerular filtration rate (GFR) is below 30 ml/mn/1.73 m2.

Changes in the Demographics and Prevalence of Chronic Kidney Disease in Okinawa, Japan (1993 to 2003)

To compare the risk factor demographics and the prevalence of chronic kidney disease (CKD), we analyzed two databases from the 1993 (N=143,948) and 2003 (N=154,019) mass screenings in Okinawa, Japan (Okinawa General Health Maintenance Association registry). We estimated the glomerular filtration rate (GFR) using serum creatinine (SCr) levels. SCr was measured by the modified Jaffe method in 1993 and by enzyme assay in 2003; the relation between the two methods was: SCr (Jaffe) = 0.194 + 1.079 x SCr (enzyme). CKD prevalence was compared using the estimated GFR calculated by the abbreviated Modification of Diet in Renal Disease (MDRD) equation. SCr was measured in 66.2% (1993) and 69.8% (2003) of the total screenees. Proteinuria was present in 3.4% (1993) and 4.3% (2003) of the total screened population, respectively. The prevalence of CKD (GFR<60 ml/min/1.73 m(2)) was similar between the two databases, being 15.7% in 1993 and 15.1% in 2003. However, the demographics of the CKD risk factors changed during the study period. The mean level of systolic blood pressure decreased, whereas the prevalence of obesity and the mean levels of serum cholesterol and fasting plasma glucose increased. In 2003, the estimated prevalence of metabolic syndrome in the general population of Japan calculated using the modified National Cholesterol Education Program (NCEP) criteria was 19.1%. The prevalence of CKD was significantly associated with that of metabolic syndrome: the age- and sex-adjusted odds ratio was 1.332 (95% confidence interval [CI], 1.277-1.389; p<0.0001). In conclusion, the demographics of the participants of the general screenings in Okinawa, Japan differed between the 1993 and 2003 screenings, but the prevalence of CKD seemed to be similar, or at least did not increase substantially, between the two databases.

Risk factors for chronic kidney disease in a community-based population: a 10-year follow-up study

The purpose of this study was to explore risk factors affecting the incidence of chronic kidney disease (CKD) in general population. We conducted a 10-year follow-up study with 123 764 (male: 41 012, female: 82 752) adults aged 40 years and over who received community-based annual examinations. The primary outcome for the analysis was the development of CKD during the follow-up period. Predictors for the development of CKD were obtained by the significant hazard ratios (HR) in Cox regression model by sex. During the follow-up period, 4307 subjects (male: 2048, female: 2259) developed CKD stage I or II, and 19 411 subjects (male: 4257, female: 15 154) developed CKD stage III or higher. The baseline-adjusted predictor of developing CKD included age, glomerular filtration rate, hematuria, hypertension, diabetes, serum lipids, obesity, smoking status, and consumption of alcohol. Treated diabetes in male subjects, and treated hypertension, systolic blood pressure >160 mm Hg and/or diastolic blood pressure >100 mm Hg, diabetes, and treated diabetes in female subjects were associated with more than a doubling of the HR. For the development of CKD stage III or higher, proteinuria of >or= + +, and proteinuria and hematuria were associated with more than a doubling of the HR in male subjects. The prevalence of newly developed CKD over 10 years was 23 718 subjects (19.2%) in adults. This study suggested that not only hypertension and diabetes but also several metabolic abnormalities were independent risk factors for developing CKD.

Time to abandon microalbuminuria?

The term microalbuminuria--a urinary albumin excretion (UAE) between 20 and 200 microg/min--has been introduced to identify subjects at increased risk of renal and cardiovascular disease. However, the relationship between albuminuria and risk is not restricted to the microalbuminuric range and extends to as low as 2-5 microg/min. On the contrary, the increase of UAE above 200 microg/min (macroalbuminuria) heralds the onset of proteinuria (urinary protein excretion above 0.5 g/24 h) and progressive renal and cardiovascular disease. Albuminuria is a component of the metabolic syndrome and may represent a marker of the increased risk of renal and cardiovascular disease associated with insulin resistance and endothelial dysfunction. Proteinuria is a sign of established kidney damage and plays a direct pathogenic role in the progression of renal and cardiovascular disease. Albuminuria reflects functional and potentially reversible abnormalities initiated by glomerular hyperfiltration, proteinuria, a size-selective dysfunction of the glomerular barrier normally associated with glomerular filtration rate (GFR) decline that may result in end-stage renal disease. Thus, the limit of 200 microg/min segregates patients with albuminuria or proteinuria who are at quite different risk. Among subjects with albuminuria, however, there is a continuous relationship between albumin excretion and risk and no lower bound between normal albuminuria and microalbuminuria can be identified that segregates subjects at different risk. Thus, the terms microalbuminuria and macroalbuminuria could be replaced by the concepts of albuminuria- and proteinuria-associated diseases. Future studies are needed to identify levels of albuminuria below which therapy is no longer beneficial.

Dyslipidemia and the progression of renal disease in chronic renal failure patients

Dyslipidemia is a common complication of progressive kidney disease and contributes to the high cardiovascular morbidity and mortality of chronic kidney disease (CKD) patients. Recent evidence also suggests a role for dyslipidemia in the development and progression of renal disease. Experimental studies have demonstrated that lipids may induce glomerular and tubulointerstitial injury, and that lipid-lowering treatments ameliorate renal injury. Various lipid abnormalities have been associated with the development and progression of renal disease in diabetic and nondiabetic patients. Population-based studies and studies of diabetic patients have reported associations of various lipid abnormalities with the development of renal disease. In patients with CKD, lipid abnormalities have also been associated with renal disease progression. Post hoc analyses of some large clinical trials on patients with vascular disease, diabetes, or dyslipidemia, and a meta-analysis of small, prospective, controlled studies on patients with CKD (diabetics and nondiabetics) suggest that statins may slow the progression of kidney disease. It is unclear whether the beneficial renal effects of statins are due to the reduction of serum cholesterol levels and/or their pleiotropic effects. There is also evidence for synergistic renoprotective effects between statins and renin-angiotensin system inhibitors. According to the results of post hoc analysis of several studies, treatment with fibrates does not seem to confer renoprotection, but evidence is scarce. In summary, there is growing evidence that lipid abnormalities may be a risk factor for renal disease, and that statins appear to confer a renoprotective effect.

Metabolic syndrome and chronic kidney disease in Okinawa, Japan

We assessed the prevalence of chronic kidney disease (CKD) in a hospital-based screening program in Okinawa, Japan. The significance of metabolic syndrome as a determinant of CKD was examined using multivariate logistic regression analysis. A total of 6980 participants, aged 30-79 years, participated in a screening program in Tomishiro Chuo Hospital. Metabolic syndrome was defined according to the criteria of the Adult Treatment Panel III (ATP III). Data were also analyzed according to the modified criteria of the National Cholesterol Education Program (NCEP) that defines abdominal obesity as a waist circumference of > oe =85 cm in men and > or =90 cm in women. CKD was defined as dipstick proteinuria (> or =1+) or a reduced glomerular filtration rate (GFR). GFR was estimated using the abbreviated Modification of Diet in Renal Disease (MDRD) formula. The prevalence of metabolic syndrome and CKD was 12.8 and 13.7%, respectively. Metabolic syndrome was a significant determinant of CKD (adjusted odds ratio (OR) 1.537 and 95% confidence interval (CI) 1.277-1.850, P<0.0001). The adjusted OR (95% CI) was 1.770 (1.215-2.579, P=0.0029) for those with four metabolic syndrome risk factors compared to those with no metabolic syndrome risk factors. Metabolic syndrome was a significant determinant for younger participants (<60 years; OR 1.686, 95% CI 1.348-2.107, P<0.0001), but not for older participants (> or =60 years; OR 1.254, 95% CI 0.906-1.735, NS). The relationship between the number of metabolic syndrome risk factors and the prevalence of CKD was linear using the modified criteria. The results suggest that metabolic syndrome is a significant determinant of CKD in men under 60 years of age, in Okinawa, Japan.

Body mass index and angiotensin-dependent control of the renal circulation in healthy humans

Obesity is increasingly recognized as a risk factor for renal disease, but the mechanism is unclear. Renal plasma flow response to captopril, as an index of renin-angiotensin system activity, was measured by para-aminohippurate clearance technique in 100 healthy, normotensive subjects in balance on a high-salt diet. Of the 100 subjects, body mass index exceeded 25 in 56 and exceeded 30 in 22. The average vasodilator response to captopril was 27+/-7 mL/min per 1.73 m2 (P<0.0001). After adjustment for other predictors of the renal plasma flow response to captopril using a multivariate linear regression model, there was a highly significant relationship between age- and plasma renin activity-adjusted body mass index and the renal plasma flow response to captopril; however, a quadratic model provided a substantially better fit (r=0.55; P<0.0001; P=0.03 versus linear correlation). The strong association between increasing body mass index and angiotensin-dependent control of the renal circulation suggests that this may be a mechanism by which obesity contributes to renal disease. Weight loss should be considered in the overweight or obese patient for renal protection.

Associations of microalbuminuria and blood pressure with carotid, aortic and femoral atheromatous plaques in elderly Finns

AIMS

To evaluate the possible associations of microalbuminuria (MA) and blood pressure (BP) with the ultrasonographic manifestations of carotid, aortic and femoral atherosclerosis in 65-year-old Finns.

METHODS

Ultrasonographic measurements were performed on 54 diabetic subjects, 97 subjects with impaired glucose tolerance (IGT) and 57 normoglycemic subjects (NGT). Urinary albumin and creatinine concentrations were measured from an early morning spot urine sample, and the urinary albumin-to-creatinine ratio (ACR) of > or = 2.5 mg/mmol in men and > or = 3.5 mg/mmol in women was used as a measure of MA. Hypertension was defined as either a systolic BP of > or = 160 mmHg or a diastolic BP of > or = 95 mmHg or being on antihypertensive medication.

RESULTS

Eighteen subjects were microalbuminuric and 176 subjects normoalbuminuric. MA was associated with diabetes mellitus and high systolic and diastolic BP. The subjects were divided into two groups according to the median total number of carotid, aortic and femoral plaques: > or = 9 versus 0-8 plaques. A high number of plaques were associated with hypertension, male gender, smoking and MA. When the study subjects were stratified according to hypertension, it turned out that MA was associated with a high number of plaques in hypertensive, but not in nonhypertensive subjects. According to the results of logistic regression analysis with a high number of plaques as the dependent variable, the unadjusted OR for smoking was 6.0 (95% CI 2.4-15.3) in hypertensive subjects. Microalbuminuria was of borderline statistical significance (OR 4.5, 95% CI 0.9-22.9). After adjustment for systolic blood pressure and fasting glucose concentration, the OR for microalbuminuria was reduced to 3.3 (95% CI 0.6-18.4).

Lifestyle modification and progressive renal failure

There is increasing evidence that lifestyle factors impact on the risk of developing chronic kidney disease (CKD) and the risk of progression of CKD. Equally important is the consideration that patients with CKD are more likely to die from cardiovascular disease than to reach the stage of end-stage renal failure. It is advantageous that manoeuvres that interfere with progression at the same time also reduce the risk of cardiovascular events. Lifestyle factors that aggravate progression include, among others, smoking, obesity and dietary salt intake. Alcohol consumption, according to some preliminary information, has a bimodal relationship to cardiovascular risk and progression, with moderate consumption being protective.

Body mass index and the risk of development of end-stage renal disease in a screened cohort

BACKGROUND

Obesity is associated with proteinuria and could be a risk factor for end-stage renal disease (ESRD). However, few studies have examined the significance of body mass index (BMI) as a risk factor for the development of ESRD in the general population.

METHODS

We examined the relationship between BMI and the development of ESRD using data from a 1983 community-based screening in Okinawa, Japan. Screenees who developed ESRD by the end of 2000 were identified through the Okinawa Dialysis Study registry. BMI data were available for 100,753 screenees (47,504 men and 53,249 women) aged >/=20 years. The cumulative incidence of ESRD was analyzed according to the quartile of BMI: <21.0, 21.0 to 23.1, 23.2 to 25.4, and >/=25.5 kg/m(2).

RESULTS

The mean (SD) BMI of the screenees was 23.4 (3.3) kg/m(2) (range 7.9 to 59.1 kg/m(2)); the mean was 23.4 kg/m(2) for both men and women. During the follow-up period, 404 screenees (232 men and 172 women) developed ESRD. The cumulative incidences of ESRD per 1000 screenees were, from the lowest to highest BMI quartile, 2.48, 3.79, 3.86, and 5.81. The odds ratio (95% CI) of BMI for developing ESRD, after adjustment for age, sex, systolic blood pressure, and proteinuria, was 1.273 (1.121-1.446, P= 0.0002) for men and 0.950 (0.825-1.094, not significant) for women.

CONCLUSION

We found that BMI was associated with an increased risk of the development of ESRD in men in the general population in Okinawa. The maintenance of optimal body weight may reduce the risk of ESRD.

From secondary to primary prevention of progressive renal disease: The case for screening for albuminuria

Many subjects nowadays present with end-stage renal failure and its attendant cardiovascular complications without known prior renal damage. In this report we review the evidence available to strongly suggest that the present practice of secondary prevention in those with known prior renal disease should be extended to primary prevention for those subjects in the general population who are at risk for progressive renal failure, but who had never suffered from a primary renal disease. We show that such subjects can be detected by screening for albuminuria. Elevated urinary albumin loss is an indicator not only of poor renal, but also of poor cardiovascular prognosis. In addition to diabetic subjects who are at risk for albuminuria, we also show that hypertensive, obese, and smoking subjects are more susceptible. We suggest that therapies that have been shown to lower albumin excretion, such as ACE inhibitors, angiotensin II receptor antagonists, and statins be started early in such patients to prevent them from developing clinical renal disease and its attendant cardiovascular complications.

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.

Is it time to measure microalbuminuria in hypertension?

Former guidelines on hypertension never made a commitment to the detection of microalbuminuria for screening or follow-up of hypertensive patients. On the other hand, growing evidence support the contributory role of microalbuminuria in the prediction of absolute cardiovascular risk in hypertension and document the potential relevance of this parameter to the initial choice of antihypertensive treatment. Upcoming new guidelines and diagnostic algorithms in hypertension need to underscore the clinical positioning of microalbuminuria for stratification of risk and follow-up purposes.

Blood pressure predicts risk of developing end-stage renal disease in men and women

Blood pressure as a risk factor for development of end-stage renal disease has not been fully studied, particularly in women. We studied the development of end-stage renal disease from 1983 through 2000 in 98 759 subjects, 46 881 men and 51 878 women, 20 to 98 years of age, who were screened in 1983 in Okinawa, Japan. Data for all dialysis patients registered from 1983 to 2000 in Okinawa were used to identify the screened subjects in whom end-stage renal disease developed. In follow-up, 400 subjects, 231 men and 169 women, had end-stage renal disease. Age, body mass index, and adjusted relative risk for systolic and diastolic blood pressure for both men and women were measured. When these results were compared with an optimal blood pressure, the relative risk of development of end-stage renal disease for those with high-normal blood pressure and hypertension were significant in both men and women. Hypertension is a significant risk factor for development of end-stage renal disease not only in men but also in women. Control of blood pressure within normal levels should be stressed as a strategy to prevent end-stage renal disease in both men and women.

The effects of weight loss on renal function in patients with severe obesity

Severe obesity is associated with increased renal plasma flow (RPF) and glomerular filtration rate (GFR). The aim of the present study was to examine whether weight loss may reverse glomerular dysfunction in obese subjects without overt renal disease. Renal glomerular function was studied in eight subjects with severe obesity (body mass index [BMI] 48.0 +/- 2.4) before and after weight loss. Nine healthy subjects served as controls. GFR and RPF were determined by measuring inulin and PAH clearance. In the obese group, GFR (145 +/- 14 ml/min) and RPF (803 +/- 39 ml/min) exceeded the control value by 61% (90 +/- 5 ml/min, P = 0.001) and 32% (610 +/- 41 ml/min, P < 0.005), respectively. Consequently, filtration fraction was increased. Mean arterial pressure, although normal, was higher than in the control group (101 +/- 4 versus 86 +/- 2 mmHg, P < 0.01). After weight loss, BMI decreased by 32 +/- 4%, to 32.1 +/- 1.5 (P = 0.001). GFR and RPF decreased to 110 +/- 7 ml/min (P = 0.01) and 698 +/- 42 ml/min (P < 0.02), respectively. Albumin excretion rate decreased from 16 microg/min (range, 4 to 152 microg/min) to 5 microg/min (range, 3 to 37 microg/min) (P < 0.01). Fractional clearance of albumin decreased from 3.2 x 10(-6) (range, 1.1 to 23 x 10(-6)) to 1.2 x 10(-6) (range, 0.5 to 6.8 x 10(-6)) (P < 0.02). This study shows that obesity-related glomerular hyperfiltration ameliorates after weight loss. The improvement in hyperfiltration may prevent the development of overt obesity-related glomerulopathy.

Cardiovascular risk factors are differently associated with urinary albumin excretion in men and women

Cardiovascular morbidity and mortality is not equally distributed among genders, men being more affected than women. It is not clear whether this is only related to a higher prevalence of the cardiovascular risk factors or to a similar prevalence of the risk factors as in women but a greater vascular susceptibility to these risk factors in men. This was tested by studying the association between various cardiovascular risk factors and urinary albumin excretion (UAE) in a large cohort of male and female subjects. While the prevalence of smoking and hypercholesterolemia was comparable between the genders, obesity was more common in women, and diabetes and hypertension were more frequent in men. The prevalence of microalbuminuria was about twofold higher in men. Interestingly, for a given level of any risk factor, UAE was higher in men than in women. On multivariate analysis with UAE as the dependent variable, an interaction with gender was found for the risk factors age, body mass index, and plasma glucose. Thus, for a higher age, body mass index, and glucose, the UAE is significantly increased in men when compared with women. It is concluded that gender differences exist in the association between cardiovascular risk factors and UAE. This is consistent with a larger vascular susceptibility to these risk factors in men as compared with women.

Proteinuria and the risk of developing end-stage renal disease

BACKGROUND

Dipstick urinalysis for proteinuria and hematuria has been used to screen renal disease, but evidence of the clinical impact of this test on development of end-stage renal disease (ESRD) is lacking.

METHODS

We assessed development of ESRD through 2000 in 106,177 screened patients (50,584 men and 55,593 women), 20 to 98 years old, in Okinawa, Japan, who participated in community-based mass screening between April 1983 and March 1984. We used data from the Okinawa Dialysis Study Registry to identify ESRD patients. Multivariate logistic analyses were performed to calculate adjusted odds ratio and 95% confidence interval (95% CI) for the significance of proteinuria and hematuria on the risk of developing ESRD with confounding variables such as age, gender, blood pressure, and body mass index. A similar analysis was repeated in a subgroup of screened patients in whom serum creatinine data existed.

RESULTS

During 17 years of follow-up, 420 screened persons (246 men and 174 women) entered the ESRD program. We identified a strong, graded relationship between ESRD and dipstick urinalysis positive for proteinuria; adjusted odds ratio (95% CI) was 2.71 (2.51 to 2.92, P < 0.001). Similar trends were observed after adding serum creatinine data. Compared with dipstick-negative proteinuria, adjusted odds ratio (95% CI) of proteinuria (1+) was 1.93 (1.53 to 2.41, P < 0.001) in men and 2.42 (1.91 to 3.06, P < 0.001) in women.

CONCLUSION

Proteinuria was a strong, independent predictor of ESRD in a mass screening setting. Even a slight increase in proteinuria was an independent risk factor for ESRD. Therefore, asymptomatic proteinuria warrants further work-up and intervention.

High-normal blood pressure and microalbuminuria

BACKGROUND

High-normal blood pressure (BP) is associated with increased cardiovascular risk compared with optimal BP, but no study has specifically examined the association between high-normal BP and microalbuminuria, an established predictor of future cardiovascular events.

METHODS

This was a cross-sectional study of normotensive (systolic BP [SBP] < 140 mm Hg, diastolic BP [DBP] < 90 mm Hg) individuals without diabetes with no hypertension history enrolled in the Third National Health and Nutrition Examination Survey. BP was categorized as high normal (SBP, 130 to 139 mm Hg or DBP, 85 to 89 mm Hg), normal (SBP, 120 to 129 mm Hg or DBP, 80 to 84 mm Hg), and optimal (SBP < 120 mm Hg and DBP < 80 mm Hg). We also separately examined SBP, DBP, mean arterial pressure (MAP), and pulse pressure. Microalbuminuria was defined using sex-specific cutoff values (urine albumin-creatinine ratio > or = 17 and < or = 250 microg/mg [> or =1.0 and < or =28 mg/mmol] for men and > or = 25 and < or = 355 microg/mg for women [> or =3 and < or =40 mg/mmol]). We used multivariate logistic regression to analyze the association between different BP measurements and microalbuminuria.

RESULTS

Compared with optimal BP, high-normal BP was significantly associated with increased odds of microalbuminuria (odds ratio [OR], 2.13; 95% confidence interval [CI], 1.51 to 3.01). Similarly, MAP (OR, 1.41; 95% CI, 1.15 to 1.74 per 10-mm Hg increment), SBP (OR, 1.27; 95% CI, 1.09 to 1.48 per 10-mm Hg increment), and DBP (OR, 1.29; 95% CI, 1.06 to 1.57 per 10-mm Hg increment) were significantly associated with microalbuminuria.

CONCLUSION

High-normal BP is significantly associated with microalbuminuria compared with optimal BP and may be a biomarker of the increased cardiovascular risk observed in this population.

Triglyceride, but not total cholesterol or low-density lipoprotein cholesterol levels, predict development of proteinuria

BACKGROUND

Epidemiological data about the relationship between dyslipidemia and proteinuria are sparse. We conducted a retrospective and longitudinal study in a large screened cohort to evaluate whether triglyceride, high-density lipoprotein (HDL) cholesterol, total cholesterol, and low-density lipoprotein (LDL) cholesterol levels increase the risk of development of proteinuria and loss of renal function.

METHODS

Post hoc analysis was performed for 4326 subjects who were free from proteinuria (dipstick 1+ or higher) at baseline (1997) with a follow-up period through 2000. Outcome measures were the development of proteinuria (1+ or higher) and change in glomerular filtration rate (GFR). Multiple logistic analysis and multiple regression analysis were used to analyze baseline characteristics related to the outcome measures.

RESULTS

During the observational period, 505 (11.7%) of subjects had one or more episodes of proteinuria (>/=1+). Adjusted relative risk of triglycerides for one or more incidences of proteinuria was 1.007 (95% CI 1.000 to 1.105, P = 0.04) in men and 1.032 (95% CI 1.004 to 1.061, P = 0.02) in women. Total cholesterol, HDL cholesterol, and LDL cholesterol were not significant predictors of proteinuria. The mean change in GFR between 1997 and 2000 was -6.3 (SD = 9.0) mL/min/1.73 m2 in men, and -7.8 (SD = 10.7) mL/min/1.73 m2 in women. HDL cholesterol (beta = 0.04, t = 3.7, P = 0.0002) in men and triglycerides (per 10 mg/dL, beta = -0.09, t = -2.2, P = 0.02) in women were correlated with the change in GFR.

CONCLUSIONS

High triglyceride levels predicted a risk of developing proteinuria in both men and women, but not total cholesterol nor LDL cholesterol. High triglyceride in women and low HDL cholesterol in men predicted the decline of renal function. It remains to be determined whether prospective treatment of dyslipidemia will protect against renal injury.

Microalbuminuria modifies the mortality risk associated with electrocardiographic ST-T segment changes

OBJECTIVES

We sought to investigate whether microalbuminuria, a proposed marker of generalized vascular damage, enhances the prognostic value of ST-T segment changes for all-cause and cardiovascular mortality in the general population.

BACKGROUND

ST-T segment changes on the rest electrocardiogram (ECG) predict mortality in the general population. However, the excess risk seems to be low, particularly in nonhospitalized populations with a low cardiovascular risk profile.

METHODS

In a population of 7,330 male and female subjects, a total of 89 deaths (1.2%) occurred during a median three-year follow-up. In 69 of these, the cause of death was obtained from the Central Bureau of Statistics: 25 subjects died of cardiovascular causes (36%). Using computerized Minnesota coding, ST-T segment changes were coded as 4.1-4 and 5.1-4. Microalbuminuria was defined as a urinary albumin excretion of 30 to 300 mg per 24 h.

RESULTS

The combination of ST-T segment changes and microalbuminuria showed a higher hazard ratio (HR) for all-cause mortality (HR 8.6 [95% confidence interval [CI] 4.8 to 15.2, p < 0.0001), as compared with ST-T segment changes in the absence of microalbuminuria (HR 1.3 [95% CI 0.7 to 2.5]), which was independent of other cardiovascular risk factors (HR 3.3 [95% CI 1.5 to 7.1], p = 0.002). The combination showed a higher HR when only cardiovascular deaths were taken into account, as compared with all-cause mortality (HR 24.5 [95% CI 7.9 to 76.0], p < 0.0001), which also counted for ST-T segment changes alone (HR 4.4 [95% CI 1.4 to 14.5], p = 0.02). After controlling for other risk factors, the HRs were 10.4 (95% CI 2.5 to 43.6, p = 0.001) for the combination and 2.7 (95% CI 0.6 to 12.3) for ST-T segment changes alone.

CONCLUSIONS

This study suggests that, in subjects with ST-T segment changes on their rest ECG, microalbuminuria could identify those at increased risk of all-cause and cardiovascular mortality.

Influence of smoking and obesity on the development of proteinuria

BACKGROUND

Proteinuria is a significant risk factor for end-stage renal disease. Previous evidence suggested that smoking and obesity increase the risk of proteinuria. However, it is unclear whether these risk factors predict the development of proteinuria independently of hypertension and diabetes mellitus. The aim of this study was to analyze the effects of obesity and smoking on the development of proteinuria in a screened cohort of subjects with normal kidney function.

METHODS

A total of 5403 subjects (3403 men and 2000 women) who participated in the 1997 and 1999 health screening examinations in Okinawa Japan, and who were normal renal function (serum creatinine < or =1.2 mg/dL in men, < or =1.0 mg/dL in women) and negative proteinuria by dipstick examination in 1997 were eligible for study. Logistic analysis was used to examine the relation between the baseline state of smoking or obesity in 1997, and the development of proteinuria in 1999, adjusted for age, sex, and other confounding factors.

RESULTS

Proteinuria developed in 5.8% of participants (6.7% in men, 4.4% in women; dipstick score, 1+ in 277, 2+ in 37, and > or =3+ in 4 participants). The incidence of proteinuria was positively associated with the number of cigarettes smoked per day (P = 0.04), and a body mass index (P < 0.0001) at baseline. Analysis showed that the relative risk (95% confidence interval) of developing proteinuria was 1.32 (1.00 to 1.74), P = 0.04 for cigarette smoking, 1.45 (1.13 to 1.86), P = 0.002 for obesity, 1.56 (1.19 to 2.06), P = 0.001 for hypertension, and 2.27 (1.55 to 3.32), P < 0.0001 for diabetes mellitus. Stratified with men and women, the relative risk was 1.28 (0.96 to 1.72), P = 0.09 for smoking, and 1.60 (1.19 to 2.14), P = 0.001 for obesity in men; the relative risk was 1.30 (0.44 to 3.80), P = 0.62 for smoking, and 1.04 (0.63 to 1.72), P = 0.87 for obesity in women.

CONCLUSIONS

Hypertension and diabetes mellitus were superior to smoking and obesity in predicting the development of proteinuria in all subjects. Stratified with men and women, obesity was a significant risk factor for the development of proteinuria independently of both hypertension and diabetes mellitus in men. The risk of developing proteinuria also tended to be increased with cigarette smoking in men. Smoking and obesity in women were not significant in this data set.

Hypertensive disorders of pregnancy in women with Type 1 and Type 2 diabetes

AIMS

Hypertensive disorders in pregnancy are common in women with Type 1 diabetes and can be associated with adverse fetal outcomes, but little is known about hypertension in pregnancy in women with Type 2 diabetes. The aim of this study was to compare the incidence and outcomes of, and risk factors for, hypertension in pregnancy in women with Type 1 and Type 2 diabetes.

METHODS

One hundred consecutive singleton pregnancies in women with Type 2 and 100 in women with Type 1 diabetes were studied. Hypertension in pregnancy was classified according to Australasian Society for the Study of Hypertension in Pregnancy guidelines. Outcomes of pregnancy examined included birth weight, rates of caesarean section, premature delivery and special care unit admission, and perinatal mortality.

RESULTS

The overall incidence of hypertension in pregnancy was similar in Type 2 and Type 1 diabetes (41% vs. 45%), but the distribution of subtypes differed (P = 0.028). Women with Type 2 diabetes had more chronic hypertension (diagnosed at < 20 weeks gestation), but less preeclampsia than women with Type 1 diabetes. Hypertension in pregnancy was strongly associated with a number of adverse outcomes, but the impact of hypertension was significantly less for Type 2 diabetes than it was for Type 1 (premature delivery, P < 0.005; admission to Special Care Unit, P < 0.01; caesarean section, P = 0.05). This was, in part, because the frequency of adverse outcomes was greater in women with preeclampsia. Nulliparity, poor glycaemic control at presentation, and early pregnancy blood pressure and not smoking were risk factors for hypertension of similar magnitude in both types of diabetes. Significant effects of duration of diabetes and obesity were not seen in Type 2 subjects, but were in Type 1 (P < 0.01, P < 0.05, respectively). Early pregnancy albumin excretion rate was increased more frequently in Type 2 subjects than in Type 1 (P < 0.035), but was less strongly associated with the development of preeclampsia (P < 0.035).

CONCLUSIONS

The incidence of hypertension in pregnancy is similar in Type 2 and Type 1 diabetes, but the different population characteristics are reflected in a significantly different pattern of types of hypertension. Hypertension has less impact on adverse outcomes in Type 2 diabetes. Some risk factors for hypertension also differ between Type 2 and Type 1 diabetes.

Microalbuminuria in hypertension is not a determinant of insulin resistance

BACKGROUND

Microalbuminuria (MA) clusters with metabolic derangements linked to the insulin resistance syndrome, and is associated with increased risk of cardiovascular disease in both diabetes and hypertension. This study questioned if MA, reflecting endothelial damage, is directly linked to impaired insulin action.

METHODS

MA was measured in two 24-hour urine samples in 84 persons with untreated hypertension recruited from a population survey (diastolic blood pressures 90 to 105 mm Hg). Thirty-one percent had MA values>20 microg/min (MA group, N = 26), and these were matched according to age, gender, and body-mass index with hypertensive persons without MA (non-MA group, N = 32) for comparison of the metabolic profile. Insulin sensitivity was measured with clamp techniques.

RESULTS

The MA and non-MA groups were similar in their fasting and post-load glucose and insulin levels, in the first (930 +/- 594 vs. 1097 +/- 707 pmol/L) and second (1111 +/- 662 vs. 1163 +/- 702 pmol/L) phases of insulin release during a hyperglycemic clamp, and in their insulin sensitivity indices (0.16 +/- 0.10 vs. 0.17 +/- 0.13, P> 0.3 for all). The MA group had higher systolic blood pressure (157 +/- 13 vs. 150 +/- 12 mm Hg, P = 0.05) and a higher serum level of circulating advanced glycation end products (AGEs; 11.0 +/- 3.0 vs. 7.9 +/- 3.5 U/mL, P = 0.05) than the controls. No associations were found between MA and the insulin sensitivity index, or glucose and insulin levels. Weak associations were found with systolic blood pressure (r = 0.25, P = 0.05), AGEs (r = 0.27, P = 0.05), and smoking habits (r = 0.39, P = 0.01).

CONCLUSION

In hypertension, MA is not a determinant of insulin resistance, provided confounding factors such as degree of adiposity are carefully controlled.

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.

Proteinuria in obstructive sleep apnea

BACKGROUND

Previous studies have reported an association between obstructive sleep apnea (OSA) and proteinuria, but are limited in their ability to assess proteinuria accurately, to adjust for confounders such as obesity, or to exclude confidently underlying renal disease in patients with OSA and nephrotic-range proteinuria.

METHODS

The spot urine protein/creatinine ratio was measured in a prospective consecutive series of 148 patients referred for polysomnography who were not diabetic and had not been treated previously for OSA. The urine protein/creatinine ratio was compared across four levels of OSA severity, based on the frequency of apneas and hypopneas per hour: <5 (absent), 5 to 14.9 (mild), 15 to 29.9 (moderate), and > or =30 (severe).

RESULTS

The median level of urine protein/creatinine ratio in all categories of OSA was <0.2 (range 0.03 to 0.69; median 0.06 in patients with normal apnea hypopnea index, 0.06, 0.07, 0.07 in patients with mild, moderate, and severe OSA, respectively). Eight subjects had a urine protein/creatinine ratio greater than 0.2. Univariate analysis showed a significant association between urine protein/creatinine ratio and older age (P < 0.0001), hypertension (P < 0.0001), coronary artery disease (P = 0.003), and arousal index (P = 0.003). Body mass index (P = 0.16), estimated creatinine clearance (P = 0.17), and apnea hypopnea index (P = 0.13) were not associated with the urine protein/creatinine ratio. In multiple regression analysis, only age and hypertension were independent positive predictors of the urine protein/creatinine ratio (P < 0.0001, R2 = 0.17).

CONCLUSION

Clinically significant proteinuria is uncommon in sleep apnea. Nephrotic range proteinuria should not be ascribed to sleep apnea and deserves a thorough renal evaluation.

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.

Microalbuminuria is common, also in a nondiabetic, nonhypertensive population, and an independent indicator of cardiovascular risk factors and cardiovascular morbidity

OBJECTIVES

To assess the prevalence of microalbuminuria in the general population, especially in nondiabetic and nonhypertensive subjects, and its association with known cardiovascular risk factors and cardiovascular morbidity.

DESIGN

Cross-sectional cohort study.

SETTING

Inhabitants of the city of Groningen, the Netherlands.

SUBJECTS

All inhabitants, aged between 28 and 75 years, were send a postal questionnaire and a vial to collect an early morning urine sample (n = 85 421). Of these 40 856 subjects (47.8%) responded. Cardiovascular risk factors and morbidity were validated in a well defined nondiabetic and nonhypertensive group of 5241 subjects.

MAIN OUTCOME MEASURES

Microalbuminuria, self-reported cardiovascular risk and cardiovascular morbidity in the total study cohort, and additionally more detailed measurements in a subset of the total population.

RESULTS

Microalbuminuria (20-200 mg L-1) was present in 7.2% of the subjects and independently associated with age, gender, hypertension, diabetes, smoking, previous myocardial infarction and stroke. Some of these associations were already observed at albuminuria levels of 10-20 mg L-1. After exclusion of the diabetic and hypertensive subjects, microalbuminuria was still prevalent in 6.6% of the subjects.

CONCLUSIONS

Microalbuminuria appears to be common not only in the general population but also in a nondiabetic, nonhypertensive population and is independently associated with increased cardiovascular risk factors and cardio-vascular morbidity. Importantly, some of these associations are present at urinary albumin levels currently considered to be normal. These findings suggest that urinary albumin measurements may be useful in early risk profiling and prevention of cardiovascular disease in the population at large.

Microalbuminuria is associated with the insulin resistance syndrome independent of hypertension and type 2 diabetes in the Korean population

To investigate whether microalbuminuria is associated with the insulin resistance syndrome independent of hypertension and type 2 diabetes, we studied the association between microalbuminuria and features of insulin resistance syndrome in Korean general population. We selected 1006 subjects by a random cluster sampling among residents aged >40 years living in the Chung-Up district, a rural area of South Korea. Subjects were stratified by oral glucose tolerance status [normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetes mellitus], and by the presence or absence of hypertension. Urinary albumin excretion rate (UAER) was determined using timed overnight urine collection. Various cardiovascular risk factors including anthropometric indices, serum lipid, true insulin and proinsulin concentrations were also measured. The prevalence of microalbuminuria (UAER between 20 and 200 microg/min) increased as the glucose tolerance worsened (6.0% in NGT, 11.8% in IGT, and 21.8% in diabetes; chi(2) trend=25.9, P<0.001). Subjects with microalbuminuria had a higher body mass index (BMI), waist-to-hip circumference ratio (WHR), systolic and diastolic blood pressure (BP), fasting and 2 h plasma glucose, fasting plasma insulin and proinsulin levels, and lower HDL-cholesterol level than subjects without microalbuminuria. In multiple regression analysis, BMI, diastolic BP, 2 h plasma glucose, and fasting plasma insulin levels were found to be independent factors associated with UAER. Multiple logistic regression analysis showed that not only diabetes mellitus and hypertension, but also fasting hyperinsulinemia and waist-to-hip ratio were independent factors associated with the presence of microalbuminuria. When the normotensive, non-diabetic subjects were analyzed separately, fasting hyperinsulinemia and impaired glucose tolerance remained independent variables associated with the presence of microalbuminuria. These results show that microalbuminuria in the Korean general population is associated with hyperinsulinemia and central obesity, and suggest that microalbuminuria is a feature of the insulin resistance syndrome independent of hypertension or type 2 diabetes.

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.