Cystatin C and creatinine in an HIV cohort: the nutrition for healthy living study.

BACKGROUND: Human immunodeficiency virus (HIV)-infected persons have an increased risk of chronic kidney disease (CKD). Serum creatinine level may underestimate the prevalence of CKD in subjects with decreased lean body mass or liver disease. Level of serum cystatin C, an alternative kidney function marker, is independent of lean body mass. STUDY DESIGN: Cross-sectional. SETTING & PARTICIPANTS: 250 HIV-infected subjects on highly active antiretroviral therapy in the Nutrition for Healthy Living (NFHL) cohort; 2,628 National Health and Nutrition Examination Survey (NHANES) 2001-2002 subjects. PREDICTORS & OUTCOMES: Comparison of serum creatinine levels in NFHL to those in NHANES subjects; comparison of CKD in NFHL subjects ascertained using serum creatinine versus cystatin C levels. MEASUREMENTS: Standardized serum creatinine, serum cystatin C, glomerular filtration rate (GFR) estimated from serum creatinine and cystatin C levels. RESULTS: Creatinine levels were lower in NFHL than NHANES subjects despite greater rates of hepatitis, diabetes, and drug use (mean difference, -0.18 mg/dL; P < 0.001 adjusted for age, sex, and race). Of NFHL subjects, only 2.4% had a creatinine-based estimated GFR less than 60 mL/min/1.73 m(2), but 15.2% had a cystatin-based estimated GFR less than 60 mL/min/1.73 m(2). LIMITATIONS: GFR was estimated rather than measured. Other factors in addition to GFR may affect creatinine and cystatin C levels. Measurements of proteinuria were not available. CONCLUSIONS: Serum creatinine levels may overestimate GFRs in HIV-infected subjects. Kidney disease prevalence may be greater than previously appreciated.

Using "socially assigned race" to probe white advantages in health status.

OBJECTIVES: We explore the relationships between socially assigned race ("How do other people usually classify you in this country?"), self-identified race/ethnicity, and excellent or very good general health status. We then take advantage of subgroups which are discordant on self-identified race/ethnicity and socially assigned race to examine whether being classified by others as White conveys an advantage in health status, even for those who do not self-identify as White. METHODS: Analyses were conducted using pooled data from the eight states that used the Reactions to Race module of the 2004 Behavioral Risk Factor Surveillance System. RESULTS: The agreement of socially assigned race with self-identified race/ethnicity varied across the racial/ethnic groups currently defined by the United States government. Included among those usually classified by others as White were 26.8% of those who self-identified as Hispanic, 47.6% of those who self-identified as American Indian, and 59.5% of those who self-identified with More than one race. Among those who self-identified as Hispanic, the age-, education-, and language-adjusted proportion reporting excellent or very good health was 8.7 percentage points higher for those socially assigned as White than for those socially assigned as Hispanic (P=.04); among those who self-identified as American Indian, that proportion was 15.4 percentage points higher for those socially assigned as White than for those socially assigned as American Indian (P=.05); and among those who self-identified with More than one race, that proportion was 23.6 percentage points higher for those socially assigned as White than for those socially assigned as Black (P<.01). On the other hand, no significant differences were found between those socially assigned as White who self-identified as White and those socially assigned as White who self-identified as Hispanic, as American Indian, or with More than one race. CONCLUSIONS: Being classified by others as White is associated with large and statistically significant advantages in health status, no matter how one self-identifies.

Microalbuminuria in the US population: third National Health and Nutrition Examination Survey.

Microalbuminuria (MA) is associated with adverse health outcomes in diabetic and hypertensive adults. The prevalence and clinical significance of MA in nondiabetic populations is less clear. The purpose of this study was to generate national estimates of the prevalence of MA in the US population. Untimed urinary albumin concentrations (UACs) and creatinine concentrations were evaluated in a nationally representative sample of 22,244 participants aged 6 years and older. Persons with hematuria and menstruating or pregnant women were excluded from analysis. The percent prevalence of clinical proteinuria (UAC > or = 300 mg/L) was similar for males and females. However, the prevalence of MA (urinary albumin-creatinine ratio [ACR], 30 to 299 mg/g) was significantly lower in males (6.1%) compared with females (9.7%). MA prevalence was greater in children than young adults and increased continuously starting at 40 years of age. MA prevalence was greater in non-Hispanic blacks and Mexican Americans aged 40 to 79 years compared with similar-aged non-Hispanic whites. MA prevalence was 28.8% in persons with previously diagnosed diabetes, 16.0% in those with hypertension, and 5.1% in those without diabetes, hypertension, cardiovascular disease, or elevated serum creatinine levels. In adults aged 40+ years, after excluding persons with clinical proteinuria, albuminuria (defined as ACR > or = 30 mg/g) was independently associated with older age, non-Hispanic black and Mexican American ethnicity, diabetes, hypertension, and elevated serum creatinine concentration. MA is common, even among persons without diabetes or hypertension. Age, sex, race/ethnicity, and concomitant disease contribute to the variability of MA prevalence estimates.

Epidemic of end-stage renal disease in people with diabetes in the United States population: do we know the cause?

BACKGROUND: The number of individuals initiating renal replacement therapy in the United States population grew exponentially over the past two decades. Cases of end-stage renal diseae (ESRD) attributed to diabetes accounted for most of this increase. In this report we examined factors that may account for the increase to determine whether it truly represents an epidemic of ESRD due to diabetes. METHODS: We reviewed time trends in data of the United States Renal Data system, the Diabetes Surveillance Program of the Centers for Disease Control and Prevention, and diabetes literature. RESULTS: Recent growth of the number of individuals with diabetes accounted for less than 10% of the increase in the number of diabetes-related ESRD. Instead, most of it was due to a threefold increase in risk of ESRD in people with diabetes and, therefore, qualifies as an epidemic. Curiously, this epidemic occurred despite widening implementation of effective renoprotective therapies. Individuals with type 2 diabetes, regardless of gender, age, or race, experienced the greatest increase in risk. There is no evidence that diabetic patients have been surviving longer, so the increased risk was not attributable to the high risk associated with long duration diabetes. CONCLUSION: We hypothesize that an epidemic of ESRD has occurred in people with diabetes in the United States population over the last two decades. The nature of the factor responsible for the epidemic and the reasons it affects patients with type 2 diabetes particularly are unknown. Research efforts to identify the putative factor deserve high priority, as does a commitment of resources to provide care for the burgeoning number of patients with ESRD and type 2 diabetes.

Hypertension and renal dysfunction: NHANES III.

The incidence rate of end-stage renal disease has increased in many countries in the past 20 yr, including the United States and Singapore. The increase in ESRD incidence in the United States is primarily attributable to diabetes and to hypertension. In Singapore the major cause of ESRD is diabetes, however the prevalence of hypertension in the Singapore population is rising rapidly, and renal complications of hypertension may become more common in the future. Information on the association of hypertension with renal dysfunction and ESRD in the United States may be useful in predicting future trends in the incidence of ESRD due to hypertension in Singapore. This paper describes published and unpublished data presented at a conference to assist in developing plans for a comprehensive renal disease prevention program in Singapore. It compares recent data on the reported prevalence of hypertension in the United States and Singapore; and presents information on the association of hypertension with serum creatinine, urinary albumin excretion, and ESRD in the United States.

Time trends in reported prevalence of kidney stones in the United States: 1976-1994.

BACKGROUND: A body of evidence establishes that the occurrence of kidney stone disease has increased in some communities of industrialized countries. Information on recent temporal trends in the United States is lacking and population-based data on epidemiologic patterns are limited. Study objective was to determine whether kidney stone disease prevalence increased in the United States over a 20-year period and the influence of region, race/ethnicity, and gender on stone disease risk. METHODS: We measured the prevalence of kidney stone disease history from the United States National Health and Nutrition Examination Survey (II and III), population-based, cross-sectional studies, involving 15,364 adult United States residents in 1976 to 1980 and 16,115 adult United States residents in 1988 to 1994. RESULTS: Disease prevalence among 20- to 74-year-old United States residents was greater in 1988 to 1994 than in 1976 to 1980 (5.2% vs. 3.8%, P < 0.05), greater in males than females, and increased with age in each time period. Among 1988 to 1994 adults, non-Hispanic African Americans had reduced risk of disease compared to non-Hispanic Caucasians (1.7% vs. 5.9%, P < 0.05), and Mexican Americans (1.7% vs. 2.6%, P < 0.05). Also, age-adjusted prevalence was highest in the South (6.6%) and lowest in the West (3.3%). Findings were consistent across gender and multivariate adjusted odds ratios for stone disease history, including all demographic variables, as well as diuretic use, tea or coffee consumption, and dietary intake of calcium, protein, and fat did not materially change the results. CONCLUSION: Prevalence of kidney stone disease history in the United States population increased between 1980 and 1994. A history of stone disease was strongly associated with race/ethnicity and region of residence.

Predictors of loss of residual renal function among new dialysis patients.

Residual renal function (RRF) in end-stage renal disease is clinically important as it contributes to adequacy of dialysis, quality of life, and mortality. This study was conducted to determine the predictors of RRF loss in a national random sample of patients initiating hemodialysis and peritoneal dialysis. The study controlled for baseline variables and included major predictors. The end point was loss of RRF, defined as a urine volume <200 ml/24 h at approximately 1 yr of follow-up. The adjusted odds ratios (AOR) and P values associated with each of the demographic, clinical, laboratory, and treatment parameters were estimated using an "adjusted" univariate analysis. Significant variables (P < 0.05) were included in a multivariate logistic regression model. Predictors of RRF loss were female gender (AOR = 1.45; P < 0.001), non-white race (AOR = 1.57; P = <0.001), prior history of diabetes (AOR = 1.82; P = 0.006), prior history of congestive heart failure (AOR = 1.32; P = 0.03), and time to follow-up (AOR = 1.06 per month; P = 0.03). Patients treated with peritoneal dialysis had a 65% lower risk of RRF loss than those on hemodialysis (AOR = 0.35; P < 0.001). Higher serum calcium (AOR = 0.81 per mg/dl; P = 0.05), use of an angiotensin-converting enzyme inhibitor (AOR = 0.68; P < 0.001). and use of a calcium channel blocker (AOR = 0.77; P = 0.01) were independently associated with decreased risk of RRF loss. The observations of demographic groups at risk and potentially modifiable factors and therapies have generated testable hypotheses regarding therapies that may preserve RRF among end-stage renal disease patients.