Prevalence of microalbuminuria and relationship to the risk of cardiovascular disease in the Japanese population

Microalbuminuria as the Tip of Iceberg in Type 2 Diabetes Mellitus: Prevalence, Risk Factors, and Associated Diabetic Complications

Background Microalbuminuria (MA) is an important clinical marker for the early detection of kidney damage in patients with type 2 diabetes (T2DM). Urine albumin-to-creatinine ratio (ACR), also known as urine microalbumin, is a sign of diabetic nephropathy (DN), which is a prevalent complication of diabetes and can result in end-stage renal disease (ESRD) if not managed. The prevalence of MA in T2DM has been steadily increasing worldwide, making it a significant public health concern. The goal of this study was to estimate the prevalence of MA and its relationship to hypertension and other diabetic complications among people with T2DM. Methodology This descriptive cross-sectional study was conducted from February 5, 2022, to February 10, 2023, to analyse data from T2DM patients who visited the outpatient diabetic clinic of Sheikh Zayed Medical College and Hospital, Rahim Yar Khan, Pakistan. This study included a total of 640 patients, aged 35-60 years, who had been diagnosed with T2DM for at least five years and fulfilled the inclusion criteria. Data on demographic and clinical characteristics, blood pressure (BP) measurements, and laboratory investigations were collected. MA was assessed based on the ACR in a spot urine sample of more than 30 mg/l. Blood pressure greater than 140/90 or already taking anti-hypertensives was taken to constitute hypertension. Factors associated with MA like hypertension, gender, mode of diabetes treatment, duration of diabetes, glycosylated haemoglobin (HbA1c), dyslipidemia, and other diabetic complications such as retinopathy and neuropathy were also recorded. Results The prevalence of MA in this study of T2DM patients study was 39.1%. The mean age of the participants with MA was 53.9 with a standard deviation (SD) of 6.1 years, and the mean duration of diabetes was 10.1 years (SD 6.2 years); 101 (33.4%) males (n=302) and 103 (30.5%) females (n=338) had MA.  There was a statistically significant correlation between MA > 30mg/d and hypertension (p = <0.001), diabetes duration since diagnosis (p=0.04), HbA1C level (p = <0.001), dyslipidemia (p=0.001), therapy type (p = <0.001), triglyceridemia (p = 0.03), history of diabetes retinopathy (p= <0.002), and peripheral neuropathy (p= <0.001). However, there was no statistically significant correlation between MA and age (p = 0.56), female gender (p = 0.08), low- and high-density lipids, or statin use (p = 0.06). Conclusion The prevalence of microalbuminuria among T2DM patients is significantly high (39.1%) and is positively correlated with various factors such as male gender, hypertension, suboptimal control of diabetes mellitus, high HbA1c levels, longer disease duration, dyslipidemia with high triglycerides, treatment modalities of T2DM, and other diabetic complications like neuropathy and retinopathy. As diabetes is very prevalent in our country, the number of patients with diabetic kidney disease will rise significantly in the near future, leading to ESRD and other diabetic complications, and immediate intervention is needed to prevent this. Further research is warranted to explore potential interventions and evaluate their impact on patient outcomes.

Development of a Risk Model for Predicting Microalbuminuria in the Chinese Population Using Machine Learning Algorithms

Objective

Microalbuminuria (MAU) occurs due to universal endothelial damage, which is strongly associated with kidney disease, stroke, myocardial infarction, and coronary artery disease. Screening patients at high risk for MAU may aid in the early identification of individuals with an increased risk of cardiovascular events and mortality. Hence, the present study aimed to establish a risk model for MAU by applying machine learning algorithms.

Methods

This cross-sectional study included 3,294 participants ranging in age from 16 to 93 years. R software was used to analyze missing values and to perform multiple imputation. The observed population was divided into a training set and a validation set according to a ratio of 7:3. The first risk model was constructed using the prepared data, following which variables with P <0.1 were extracted to build the second risk model. The second-stage model was then analyzed using a chi-square test, in which a P ≥ 0.05 was considered to indicate no difference in the fit of the models. Variables with P <0.05 in the second-stage model were considered important features related to the prevalence of MAU. A confusion matrix and calibration curve were used to evaluate the validity and reliability of the model. A series of risk prediction scores were established based on machine learning algorithms.

Results

Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), triglyceride (TG) levels, sex, age, and smoking were identified as predictors of MAU prevalence. Verification using a chi-square test, confusion matrix, and calibration curve indicated that the risk of MAU could be predicted based on the risk score.

Conclusion

Based on the ability of our machine learning algorithm to establish an effective risk score, we propose that comprehensive assessments of SBP, DBP, FBG, TG, gender, age, and smoking should be included in the screening process for MAU.

The prevalence and risk factors of microalbuminuria in hypertensive patients under current medical treatment

OBJECTIVE

A link between urinary albumin excretion and an increased incidence of cardiovascular mortality has already been demonstrated. However, the reported prevalence of microalbuminuria (MAU) in patients with hypertension is highly variable. We therefore aimed to conduct a cross-sectional multicenter study to investigate the prevalence of urinary albumin excretion in treated hypertensive patients in our current practice.

METHODS

A total of 1,258 hypertensive patients were enrolled in this study. Patients with macroalbuminuria were excluded. The concentrations of urinary microalbumin and creatinine were measured. Urinary albumin excretion was expressed as the ratio of albumin to creatinine excretion.

RESULTS

The mean systolic and diastolic blood pressures were 130.9±12.7 mmHg and 74.7±8.9 mmHg, respectively. The overall prevalence of MAU was 42.8%, and it was observed in 35.8% of patients treated with a single medication. Patients with polyvascular disease exhibited a higher prevalence of MAU compared with patients with monovascular disease. The factors related to the presence of MAU included the estimated glomerular filtration rate (eGFR), systolic blood pressure, and glycated hemoglobin (HbA1c) level (odds ratios [ORs] of 0.988, 1.026, and 1.371, respectively).

CONCLUSION

The present study showed that the prevalence of MAU among hypertensive patients was 42.8%, even in patients whose blood pressure was relatively well controlled. Additionally, the eGFR, systolic blood pressure, and HbA1c level are risk factors for the development of MAU. These findings suggest that a substantial number of hypertensive patients have MAU and highlight the importance of strictly controlling these factors to improve patient prognosis.

Association of serum carotenoid levels with urinary albumin excretion in a general Japanese population: the Yakumo study

Background

Albuminuria is a risk factor for not only nephropathy progression but also cardiovascular disease. Oxidative stress may have a role in the positive association between albuminuria and cardiovascular disease.

Methods

This cross-sectional study investigated the associations of serum levels of carotenoids, which are dietary antioxidants, with albuminuria among 501 Japanese adults (198 men, mean age ± SD: 66.4 ± 10.0 years; 303 women, mean age ± SD: 65.4 ± 9.8 years) who attended a health examination. Serum levels of carotenoids were determined by high-performance liquid chromatography. Logistic regression analysis was used to estimate odds ratios (ORs) with 95% CIs for albuminuria after adjustment for age, body mass index, smoking habits, drinking habits, hypertension, diabetes mellitus, and dyslipidemia.

Results

Prevalence of albuminuria was 15.4% among men and 18.1% among women. Among women with albuminuria, geometric mean serum levels of canthaxanthin, lycopene, β-carotene, total carotenes, and provitamin A were significantly lower than those of normoalbuminuric women. Adjusted ORs for albuminuria among women in the highest tertiles of serum β-carotene (OR, 0.45; 95% CI, 0.20–0.98) and provitamin A (OR, 0.45; 95% CI, 0.20–0.97) were significantly lower as compared with those for women in the lowest tertile. There were no associations between serum carotenoids and albuminuria in men.

Conclusions

An increased level of serum provitamin A, especially serum β-carotene, was independently associated with lower risk of albuminuria among Japanese women.

A Comparative Study of Clinical Utility of Spot Urine Samples with 24-h Urine Albumin Excretion for Screening of Microalbuminuria in Type 2 Diabetic Patients

Twenty-four hour urinary albumin excretion (UAE) is considered as gold standard method for albuminuria measurement, but collection of 24-h urine is inconvenient. The aim of present study was to evaluate whether albumin: creatinine ratio (ACR) and urinary albumin concentration (UAC) in different spot urine samples correlate or not with 24-h UAE for screening of microalbuminuria in type 2 diabetic patients. We collected first morning void (FMV), random urine sample (RUS) and 24-h urine, separately on consecutive days from 104 type 2 diabetic patients. ACR and UAC in each spot urine sample compared with 24-h UAE with regard to Pearson correlation coefficient. Pearson's correlation of albumin: creatinine ratio (ACR) with 24-h UAE was (r = 0.802 and 0.623) in first morning void (FMV) and random urine sample (RUS), respectively. Pearson's correlation coefficient of urinary albumin concentration (UAC) compared with 24-h UAE was (r = 0.943 and 0.920), in FMV and RUS, respectively, P < 0.01. Results revealed that values in first morning void (FMV) were better correlated with 24-h urinary albumin excretion (UAE), than the values in random urine sample (RUS). We conclude that the first morning void (FMV) may be able to replace 24-h urine collection, preferably urinary albumin concentration (UAC) in the initial screening of microalbuminuria in diabetic patients.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s12291-011-0136-0) contains supplementary material, which is available to authorized users.

Establishment of a method to detect microalbuminuria by measuring the total urinary protein-to-creatinine ratio in diabetic patients

Diabetes and chronic kidney disease (CKD) which are risk facters of cardiovascular disease, are increasing global public health problems. Microalbuminuria is an early sign of progressive cardiovascular and renal disease in individuals with or without diabetes. Screening for microalbuminuria and early treatment are recommended for patients with increased cardiovascular and renal risk factors. However, the procedure used to measure urinary albumin is expensive. Alternatively, the measurement of total urinary protein is simple and inexpensive. Thus, we aimed to establish a method that could predict the presence of microalbuminuria by measuring the total protein-to-creatinine ratio. Spot urine samples were obtained from 150 patients with diabetes mellitus, and the total protein-to-creatinine ratio and the albumin-to-creatinine ratio (ACR) were measured. There was a significant positive correlation between the protein-to-creatinine ratio and the ACR (r = 0.95). The presence of albuminuria (both micro- and macroalbuminuria) could be predicted from the value of the protein-to-creatinine ratio in more than 90% of patients. A receiver-operating characteristic curve analysis revealed that the protein-to-creatinine ratio had a sensitivity and a specificity of 90.8% and 91.9%, respectively, for the detection of albuminuria and a cutoff value of 0.091 g/g creatinine. These results suggest that screening for microalbuminuria can be replaced by the detection of the protein-to-creatinine ratio, which may be cost-effective for patients with cardiovascular risks as well as for the general population.

Polymorphism of proinflammatory cytokine genes and albuminuria in the Japanese general population: the Takahata study

BACKGROUND

A cluster of proinflammatory cytokines plays an important role in the development of various renal diseases, and the expression of these cytokines is genetically modified. To examine the association between polymorphisms of proinflammatory cytokine genes and albuminuria, a cross-sectional study was conducted in the general population.

METHODS

Single nucleotide polymorphisms (SNPs) in six proinflammatory cytokine genes, including interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, CC chemokine ligand 1 (CCL1) and monocyte chemoattractant protein-1 (MCP-1), were genotyped in 2927 Japanese subjects. Urine albumin-creatinine ratio (UACR) was measured in morning spot urine samples.

RESULTS

Albuminuria (UACR ≥ 30 mg/g) was significantly associated with the A/A + A/G genotype at rs2069852 in the IL-6 gene (P = 0.01) and the A/A genotype at rs228269 in the CCL1 gene (P = 0.002). Multivariate analysis with adjustment for traditional risk factors showed that these genotypes independently predicted albuminuria [odds ratio (OR) 1.782, 95% confidence interval (CI) 1.171-2.712, P = 0.007 for the A/A + A/G genotype at rs2069852 in IL-6, and OR 1.432, 95% CI 1.128-1.770, P = 0.003 for the A/A genotype at rs228269 in CCL1]. The prevalence of albuminuria and the UACR were increased along with the increase of risk genotypes.

CONCLUSIONS

This study revealed that SNPs in the IL-6 and CCL1 genes were associated with albuminuria, and the combination of these genotypes had an additive effect on the prevalence and severity of albuminuria. This indicates that genetic factors influencing inflammatory responses may affect the development of renal injury in the Japanese general population.

Prevalence and risk factors of microalbuminuria in Thai nondiabetic hypertensive patients

PURPOSE

To assess the prevalence and risk factors of microalbuminuria in nondiabetic hypertensive patients in Thailand.

PATIENTS AND METHODS

A cross-sectional study was performed during January to December 2007 at outpatients departments of Bhumibol Adulyadej hospital. Nondiabetic hypertensive patients without a history of pre-existing kidney diseases participated in this study. A questionnaire was used for collecting information on demographics, lifestyle, and family history of cardiovascular and kidney disease. Spot morning urine samples were collected for albuminuria estimation. Albuminuria thresholds were evaluated and defined using albumin-creatinine ratio (ACR).

RESULTS

A total of 559 hypertensive patients (283 males, 276 females), aged 58.0 +/- 11.6 years were enrolled in this study. Microalbuminuria (ACR 17 to 299 mg/g in males and 25 to 299 mg/g in females) was found in 93 cases (16.6%) [15.0%-18.2%]. The independent determinants of elevated urinary albumin excretion in a multiple logistic regression model were; body mass index > or =30 (odds ratio (OR) = 2.24, 95% confidence intervals (CI): 1.33-3.76) and dihydropyridine calcium channel blockers (DCCB) use (OR = 1.92, 95% CI: 1.22-3.02).

CONCLUSION

In Thai nondiabetic hypertensive patients, microalbuminuria was not uncommon. Obesity and use of dihydropyridine calcium channel blocker were found to be the important predictors. Prognostic value of the occurrence of microalbuminuria in this population remains to be determined in prospective cohort studies.

Confirming the Utility of Four Kidney Biomarker Tests in a Longitudinal Follow-Up Study

In this follow-up study, 526 persons were followed for almost 5 years to assess the reversibility and predictive value of four kidney biomarkers in a field epidemiology setting. This study examined (a) whether elevations in urinary albumin, N-acetyl-beta-D-glucosaminidase, retinol-binding protein, and alanine aminopeptidase remained elevated at follow-up and (b) whether these initial elevations were predictive of kidney disease (as measured by markers of kidney dysfunction: serum creatinine, serum cystatin C, creatinine clearance, and urine osmolality) at follow-up. Study participants were 8-76 years of age at baseline and were followed for an average of 4.5 years. Approximately 50% of adults who had an elevated biomarker did not have an elevation at followup. Youths with elevated biomarkers at baseline, but who completed adolescence by the time of the follow-up, no longer had any elevations in biomarkers at follow-up. Adult participants who had elevated biomarkers and selected health conditions at baseline (diabetes and, to a lesser extent, heart disease, hypertension, gout, and urinary tract disease) were more likely to show early indicators of kidney impairment at follow-up. Participants with these health conditions and normal kidney biomarker values at baseline had kidney test results at follow-up that were similar to results of study participants who did not have these health conditions at baseline. The presence or absence of elevated biomarkers at baseline among generally healthy participants was not associated with the development of early indicators of kidney impairment at follow-up. This longitudinal study confirmed the utility of these four kidney biomarker tests as markers of preclinical organ dysfunction among adults with certain preexisting medical conditions.

Changes in albumin excretion in the diabetes prevention program

OBJECTIVE

Increased urinary albumin excretion rates have been linked to nephropathy and macrovascular disease. We here describe the baseline prevalence and effect of Diabetes Prevention Program (DPP) interventions on the development and reversal of elevated albumin excretion.

RESEARCH DESIGN AND METHODS

Urine albumin-to-creatinine ratios (ACRs) were calculated from untimed urine collections. Analyses compared participants by treatment group, diabetes and hypertension status, and use of ACE inhibitors or angiotensin II receptor blockers (ARBs).

RESULTS

Elevated ACR levels (>or=30 mg/g creatinine) were present at baseline in 198 (6.2%) of 3,188 participants: placebo 5.3%, metformin 6.5%, and intensive lifestyle (ILS) 6.8%. Of the 2,802 with ACR measurements at baseline and at the end of the study, the percentage with elevated levels declined (incident and regression) from 6.2 to 6.1%, with no significant differences between the groups even with adjustment for ACE inhibitor and ARB use. The odds of developing an elevated ACR were 59% higher for a participant who developed diabetes compared with one who did not.

CONCLUSIONS

At entry into the DPP, an elevated ACR was present in 6.2%. Despite the marked decrease in progression to diabetes and the improvement in insulin resistance and other cardiovascular risk markers in the ILS and metformin groups, there was no improvement in ACR, on average, in those two groups. However, the frequency of an elevated ACR was higher in participants who developed diabetes. An increased ACR may have multiple causes, thus obscuring the improvements that might have been expected with the reduction in insulin resistance seen in the DPP.

Microalbuminuria in Thai essential hypertensive patients

Essential hypertensive patients (176 males and 329 females), aged 58.0+/-11.2 years were enrolled in a cross-sectional study conducted from February to March 2006 to investigate the prevalence and risk factors for microalbuminuria in hypertensive patients attending the Outpatient Department of Siriraj Hospital, Bangkok, Thailand. Macroalbuminuria was detected in 11 (2.2%) patients and microalbuminuria in 94 (18.6%) patients. Only male aged>or=45 years or female aged>or=55 years correlated significantly with a high occurrence of microalbuminuria, while calcium channel blocker and statin users were protected against microalbuminuria. The presence of microalbuminuria was not associated with age>or=60 years, male gender, current/previous smokers, hypertension duration>or=10 years, lack of blood pressure normalization, metabolic syndrome, use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and multi-drug use. Risk factor recognition for microalbuminuria will enable physicians to identify cases that should be screened for microalbuminuria.

The protective effects of angiotensin II blockade with olmesartan medoxomil on resistance vessel remodeling (The VIOS study): rationale and baseline characteristics

BACKGROUND

The VIOS (Vascular Improvement with Olmesartan medoxomil Study) study is a randomized, parallel study to determine the relative effects of suppressing the renin-angiotensin system (RAS) with the angiotensin receptor antagonist olmesartan medoxomil versus suppressing sympathetic drive with the beta-adrenoceptor antagonist atenolol on remodeling of the subcutaneous small resistance vessel. Remodeling of small resistance vessels may be the earliest pathologic finding associated with hypertension. It may predate the onset of clinically apparent hypertension.

METHODS

In this study, 100 patients with stage I hypertension are characterized at baseline before being treated for 1 year to obtain a goal BP of less than 140/90 mm Hg as defined by Joint National Committee (JNC)-7. Resistance vessel remodeling is determined using the gluteal fat biopsy technique in the hypertensive patients and a group of normotensive healthy volunteers. Additionally, efforts will be made to define whether noninvasive hemodynamic parameters, retinal vessel measurement changes, or biologic markers may predict and track the underlying vascular morphologic and physiologic changes induced by either regimen during the 12-month treatment period.

RESULTS

The primary endpoint will be the degree of vascular remodeling as obtained from percutaneous biopsy of gluteal subcutaneous resistance vessels in each of two treatment arms compared with the normal volunteers. The design of the study and the pertinent baseline characteristics of these patients with uncomplicated essential hypertension are presented.

CONCLUSION

The suppression of the RAS by the blockade of angiotensin II type 1 (AT(1)) receptors may demonstrate remodeling effects on the ubiquitous small resistance vessels similar to that seen in the myocardium and renal glomeruli, thus affording more complete end-organ protection.

Prevalence and risk factor analysis of microalbuminuria in Japanese general population: the Takahata study

Microalbuminuria, an indicator of glomerular injury, is associated with increased risk of progressive renal deterioration, cardiovascular disease, and mortality. However, the prevalence of microalbuminuria in Japanese general population is less certain. Thus, we examined the prevalence of microalbuminuria and its associated risk factors in Japan. Subjects of this cross-sectional study were asymptomatic individuals over 40 years in Takahata, Japan. Urine albumin-creatinine ratio was calculated from a single-spot urine specimen collected in the morning. Creatinine clearance (CCr) was obtained by Cockcroft-Gault equation. Multivariate logistic regression analysis was used to determine which risk factors (i.e., age, hypertension, diabetes, obesity, and salt intake) might predict the presence of microalbuminuria. A total of 2321 subjects (mean age, 64 years; men, 1034; women, 1287) were entered into the final analysis. Among them, the prevalence of microalbuminuria, macroalbuminuria, and proteinuria by dipstick test (> or = 1+) were 317 (13.7%), 39 (1.7%), and 103 (4.4%), respectively. Age, hypertension, and diabetes were independently associated with microalbuminuria in men. In addition to the classical risk factors detected in men, estimated 24-h urinary sodium excretion and uric acid were also independently associated with microalbuminuria in women. Among the 668 subjects with renal insufficiency (CCr <60 ml/min/1.73 m(2)), the prevalence of microalbuminuria and macroalbuminuria were 119 (17.8%) and 18 (2.7%), respectively. In conclusion, microalbuminuria is prevalent across all age groups and is associated with lifestyle-related risk factors in Japanese general population. However, there are a substantial number of subjects with renal insufficiency accompanying no microalbuminuria.

Urinary creatinine concentration is inversely related to glycaemic control and the presence of some diabetic complications in patients with newly diagnosed Type 2 diabetes

BACKGROUND

The ratio between urinary albumin concentration (UAC) and urinary creatinine concentration (UCC) is widely used to estimate renal involvement. We examined how UAC and UCC associate with each other, with other risk factors, and with diabetic complications in a population-based sample of Type 2 diabetic patients.

METHODS

A freshly voided morning urine specimen was provided by 1,284 consecutive, newly diagnosed diabetic patients aged 40 years or over in general practice. Albumin was measured by a polyethyleneglycol radioimmunoassay and creatinine by a modified Jaffe method.

RESULTS

In a multivariate model including UAC, UCC, age, sex, HbA1c, and urinary glucose concentration, UAC increased with both age (P=.042) and HbA1c (P=.014), while UCC decreased (P<.001 and P<.001, respectively). In two regression models, the prevalence of diabetic retinopathy (P<.001) and relatively high resting heart rate (P<.001) increased with increasing UAC but decreased with increasing UCC (P=.002 and P=.005, respectively).

CONCLUSION

The use of albumin/creatinine ratio (ACR) may introduce bias of unpredictable size and direction in comparisons of ACR with variables that are associated with UCC in their own right. In daily clinical practice, renal involvement in the individual patient can be estimated reliably with UAC or ACR measured in a freshly voided morning urine specimen, especially when considered together. However, the associations of the combined measure ACR should be interpreted with great caution in clinical and epidemiological research.

An alarmingly high prevalence of diabetic nephropathy in Asian type 2 diabetic patients: the MicroAlbuminuria Prevalence (MAP) Study

AIM/HYPOTHESIS

Microalbuminuria represents the earliest clinical evidence of diabetic nephropathy and is a marker of increased cardiovascular morbidity and mortality. Its early detection allows the implementation of individualised and aggressive intervention programmes to reduce cardiovascular risk factors. There is limited information on the prevalence of microalbuminuria among hypertensive type 2 diabetic patients in Asia.

METHODS

This cross-sectional epidemiological study aimed to assess the prevalence of microalbuminuria and macroalbuminuria among consecutively screened hypertensive type 2 diabetic adult patients in 103 centres in 10 Asian countries or regions. Predictive factors for microalbuminuria and macroalbuminuria were characterised using a stepwise logistic regression model.

RESULTS

A total of 6,801 patients were enrolled and 5,549 patients constituted the per-protocol population (patients with bacteriuria and haematuria were excluded). The prevalence of microalbuminuria was 39.8% (39.2-40.5; 95% CI) and the prevalence of macroalbuminuria was 18.8% (18.2-19.3; 95% CI). Only 11.6% of the patients had systolic and diastolic blood pressure below the 130/80 mm Hg target. In the multivariate analyses, the predictive factors for the presence of microalbuminuria were age, BMI, systolic blood pressure and ethnic origin. The highlighted predictive factors for the presence of macroalbuminuria were age, sex, ethnic origin, BMI, duration of diabetes, presence of diabetic complications, intake of diuretics, intake of calcium channel blockers, diastolic and systolic blood pressure.

CONCLUSIONS/INTERPRETATION

The high prevalence (58.6%) of micro or macroalbuminuria observed in these patients is alarming and indicates an impending pandemic of diabetic cardiovascular and renal diseases in Asia with its potential economic consequences.

Evaluation of measures of urinary albumin excretion in epidemiologic studies

Twenty-four-hour urinary albumin excretion (UAE) is considered the gold standard for determining albumin level in epidemiologic studies, but this measure is inconvenient and often unavailable. Simpler alternatives include the albumin:creatinine ratio (ACR) and urinary albumin concentration (UAC) obtained from a single sample. The authors assessed the strengths and weaknesses of ACR and UAC as alternatives to UAE using albumin measurements from two 24-hour urine samples collected in 1996-1999 from 4,678 participants aged 40-59 years in the International Study of Macronutrients and Blood Pressure (17 population samples from four countries). The authors compared ACR and UAC with regard to correlations with UAE, daily within-person variability, and associations with known predictors of UAE. Rank-order correlations of ACR with UAE were 0.949 and 0.942 for men and women, respectively, versus 0.881 and 0.816 for UAC. Mean within-person coefficients of variation were 34.0-40.0% for the three measures, with the smallest values being observed for UAC. Average correlations with blood pressure were similar for UAE, ACR, and UAC, but the correlation with body mass index was lower for ACR (0.118 for ACR and 0.188 for UAC vs. 0.211 for UAE) because of high correlation between body mass index and creatinine level. Thus, UAC and ACR are acceptable alternatives to the more complex UAE, and the simpler UAC may be preferable to ACR in some respects.

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.

Microalbumin measurement alone or calculation of the albumin/creatinine ratio for the screening of hypertension patients?

BACKGROUND

Spot urine sampling seems to be a reliable screening method for the detection of microalbuminuria in hypertensive patients. It remains unclear whether microalbumin measurement alone or calculation of the albumin/creatinine ratio (ACR) are more reliable for the detection of microalbuminuria in non-selected hypertensive patients.

METHODS

Following collection of a spot, midstream urine sample, urine was collected for 24 h for the measurement of microalbumin in 264 hypertensive patients. We compared microalbumin concentration in the spot urine with microalbumin measured in the 24-h urine sample and examined the utility of the ACR in evaluating microalbuminuria in hypertensive patients. Pathologic microalbuminuria was assumed when the microalbumin concentration exceeded 30 mg/l in the 24-h urine sample. Diagnostic performance is expressed in terms of specificity, sensitivity, positive (PPV) and negative predictive value (NPV), and area under receiver operating characteristics curve (AUC).

RESULTS

A total of 47 samples (17.8%) showed pathologic microalbuminuria in the 24-h urine sample. The diagnostic performance expressed as AUC was 0.94 (95% CI 0.90-0.98) for microalbumin measurement alone and 0.94 (95% CI 0.89-0.97) for ACR. The PPV and NPV were 44.2 and 97.9% for microalbumin measurement alone. ACR revealed a PPV of 29.3% and a NPV of 96.2% for males and 42.9 and 98% for females, if a cut-off value of 2.5 mg/mmol for males and of 4.0 mg/mmol for females was used.

CONCLUSIONS

The ACR did not provide any advantage compared with microalbumin measurement alone, but requires an additional determination of creatinine and the use of gender-specific cut-off values. Therefore, measurement of microalbuminuria alone in the spot urine sample is more convenient in daily clinical practice and should be used as the screening method for hypertensive patients.

Cardiovascular risk factors in normotensive and hypertensive Egyptians

OBJECTIVES

To define the prevalence of cardiovascular risk factors and their relation to the level of blood pressure, in Egyptians.

METHODS

Data were collected during the Egyptian National Hypertension project, a national hypertension survey in Egypt. During phase I of the survey, hypertensive (HT) patients were identified. In phase II, clinical and laboratory evaluations were made on HT and gender-matched normotensives (NT). A total of 2313 individuals were examined, 311 NT males, 443 NT females, 670 HT males and 889 HT females.

RESULTS

The prevalence of obesity was 33 and 47% in hypertensive men and women, respectively. After adjusting for age, HT men had significantly higher heart rate, total cholesterol (TC), triglycerides (TG), fasting blood sugar (FBS), post-prandial blood sugar (PBS), body mass index and waist/hip (W/H) ratio than their NT counterparts. In addition, HT women had higher low-density lipoprotein cholesterol (LDL-C). The prevalence of elevated LDL-C and FBS increased with age. The prevalence of hypertriglyceridemia, elevated FBS and obesity rose with increasing level of blood pressure (BP). From the 25-34 to the 55-64 age group, the percentage of hypertensives with > or = 2 risk factors rose from 42.9 to 60.6% in men, and from 9.4 to 46.2% in women. All risk factors were more prevalent in urban populations.

CONCLUSION

This is one of the few reports on the prevalence of cardiovascular risk factors in a developing country. Risk factors cluster with rising level of BP and with ageing. Obesity is very prevalent, particularly in hypertensive Egyptian women. Health efforts directed at the prevention and treatment of obesity should be a high priority.

[Prevalence of microalbuminuria and association with cardiovascular risk factors in a Spanish Mediterranean area]

BACKGROUND

The primary objective of this study was to know the prevalence of microalbuminuria (mAlb)in a general population from the Spanish Mediterranean area along with its association with other cardiovascular risk factors (CRF).

PATIENTS AND METHOD

We studied 99 consecutive patients who were classified in mAlb+ or mAlb-,depending on whether their mAlb was higher or lower than 30 mg/day,respectively.

RESULTS

Thirty-seven patients(9.3% of the general population) were mAlb positive. Twenty-one percent of them were males with hypertension. The presence of mAlb was positively correlated with age, systolic blood pressure,body mass index, waist-to-hip ratio, pulse pressure, HDL cholesterol,triglycerides, glycemia and serum creatinine. The level of mAlb was 12.9 (11.2) (mg/day) in non-hypertensive non diabetic individuals,while it was 14.1 (16.5) in diabetic non-hypertensive subjects, 22.5 (53,5) in hypertensive non-diabetic subjects and 27.7 (49.1)in diabetic individuals who were also hypertensive. Hypertension correlationed with the presence of mAlb with an odds ratio of 2.4 (CI 95%: 1.1-5.2)and the addition of a male gender increased the odds ratio to 3.8 (CI 95%: 1.8-8.1).

CONCLUSIONS

The prevalence of mAlb in the Spanish Mediterranean area appears to be low (9.3%),although it is especially high in hypertensive males with or without diabetes.