Elizabeth Hedgeman

Prevalence of Chronic Kidney Disease in US Adults with Undiagnosed Diabetes or Prediabetes

BACKGROUND AND OBJECTIVES Prevalence of chronic kidney disease (CKD) in people with diagnosed diabetes is known to be high, but little is known about the prevalence of CKD in those with undiagnosed diabetes or prediabetes. We aimed to estimate and compare the community prevalence of CKD among people with diagnosed diabetes, undiagnosed diabetes, prediabetes, or no diabetes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The 1999 through 2006 National Health and Nutrition Examination Survey is a representative survey of the civilian, noninstitutionalized US population. Participants who were aged > or =20 years; responded to the diabetes questionnaire; and had fasting plasma glucose (FPG), serum creatinine, and urinary albumin-creatinine ratio measurements were included (N = 8188). Diabetes status was defined as follows: Diagnosed diabetes, self-reported provider diagnosis (n = 826); undiagnosed diabetes, FPG > or =126 mg/dl without self-reported diagnosis (n = 299); prediabetes, FPG > or =100 and <126 mg/dl (n = 2272); and no diabetes, FPG <100 mg/dl (n = 4791). Prevalence of CKD was defined by estimated GFR 15 to 59 ml/min per 1.73 m(2) or albumin-creatinine ratio > or =30 mg/g; adjustment was performed with multivariable logistic regression. RESULTS Fully 39.6% of people with diagnosed and 41.7% with undiagnosed diabetes had CKD; 17.7% with prediabetes and 10.6% without diabetes had CKD. Age-, gender-, and race/ethnicity-adjusted prevalence of CKD was 32.9, 24.2, 17.1, and 11.8%, for diagnosed, undiagnosed, pre-, and no diabetes, respectively. Among those with CKD, 39.1% had undiagnosed or prediabetes. CONCLUSIONS CKD prevalence is high among people with undiagnosed diabetes and prediabetes. These individuals might benefit from interventions aimed at preventing development and/or progression of both CKD and diabetes.

Prevalence of Chronic Kidney Disease in Persons With Undiagnosed or Prehypertension in the United States

Hypertension is both a cause and a consequence of chronic kidney disease, but the prevalence of chronic kidney disease throughout the diagnostic spectrum of blood pressure has not been established. We determined the prevalence of chronic kidney disease within blood pressure categories in 17 794 adults surveyed by the National Health and Nutrition Examination Survey during 1999–2006. Diagnosed hypertension was defined as self-reported provider diagnosis (n=5832); undiagnosed hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg, without report of provider diagnosis (n=3046); prehypertension was defined as systolic blood pressure ≥120 and <140 mm Hg or diastolic blood pressure ≥80 and <90 mm Hg (n=3719); and normal was defined as systolic blood pressure <120 mm Hg and diastolic blood pressure <80 mm Hg (n=5197). Chronic kidney disease was defined as estimated glomerular filtration rate <60 mL/min per 1.73 m2 or urinary albumin:creatinine ratio >30 mg/g. Prevalences of chronic kidney disease among those with prehypertension and undiagnosed hypertension were 17.3% and 22.0%, respectively, compared with 27.5% with diagnosed hypertension and 13.4% with normal blood pressure, after adjustment for age, sex, and race in multivariable logistic regression. This pattern persisted with varying definitions of kidney disease; macroalbuminuria (urinary albumin:creatinine ratio >300 mg/g) had the strongest association with increasing blood pressure category (odds ratio: 2.37 [95% CI: 2.00 to 2.81]). Chronic kidney disease is prevalent in undiagnosed and prehypertension. Earlier identification and treatment of both these conditions may prevent or delay morbidity and mortality from chronic kidney disease.

Nonsteroidal Anti-Inflammatory Drug Use Among Persons With Chronic Kidney Disease in the United States

PURPOSE Because avoidance of nonsteroidal anti-inflammatory drugs (NSAIDs) is recommended for most individuals with chronic kidney disease (CKD), we sought to characterize patterns of NSAID use among persons with CKD in the United States. METHODS A total of 12,065 adult (aged 20 years or older) participants in the cross-sectional National Health and Nutrition Examination Survey (1999–2004) responded to a questionnaire regarding their use of over-the-counter and prescription NSAIDs. NSAIDs (excluding aspirin and acetaminophen) were defined by self-report. CKD was categorized as no CKD, mild CKD (stages 1 and 2; urinary albumin-creatinine ratio of ≥30 mg/g) and moderate to severe CKD (stages 3 and 4; estimated glomerular filtration rate of 15–59 mL/min/1.73 m2). Adjusted prevalence was calculated using multivariable logistic regression with appropriate population-based weighting. RESULTS Current use (nearly every day for 30 days or longer) of any NSAID was reported by 2.5%, 2.5%, and 5.0% of the US population with no, mild, and moderate to severe CKD, respectively; nearly all of the NSAIDs used were available over-the-counter. Among those with moderate to severe CKD who were currently using NSAIDs, 10.2% had a current NSAID prescription and 66.1% had used NSAIDs for 1 year or longer. Among those with CKD, disease awareness was not associated with reduced current NSAID use: (3.8% vs 3.9%, aware vs unaware; P=.979). CONCLUSIONS Physicians and other health care clinicians should be aware of use of NSAIDs among those with CKD in the United States and evaluate NSAID use in their CKD patients.

Estimating population distributions when some data are below a limit of detection by using a reverse kaplan-meier estimator

Background: Data with some values below a limit of detection (LOD) can be analyzed using methods of survival analysis for left-censored data. The reverse Kaplan-Meier (KM) estimator provides an effective method for estimating the distribution function and thus population percentiles for such data. Although developed in the 1970s and strongly advocated since then, it remains rarely used, partly due to limited software availability. Methods: In this paper, the reverse KM estimator is described and is illustrated using serum dioxin data from the University of Michigan Dioxin Exposure Study (UMDES) and the National Health and Nutrition Examination Survey (NHANES). Percentile estimates for left-censored data using the reverse KM estimator are compared with replacing values below the LOD with the LOD/2 or LOD/√2. Results: When some LODs are in the upper range of the complete values, and/or the percent censored is high, the different methods can yield quite different percentile estimates. The reverse KM estimator, which is the nonparametric maximum likelihood estimator, is the preferred method. Software options are discussed: The reverse KM can be calculated using software for the KM estimator. The JMP and SAS (SAS Institute, Cary, NC) and Minitab (Minitab, Inc, State College, PA), software packages calculate the reverse KM directly using their Turnbull estimator routines. Conclusion: The reverse KM estimator is recommended for estimation of the distribution function and population percentiles in preference to commonly used methods such as substituting LOD/2 or LOD/√2 for values below the LOD, assuming a known parametric distribution, or using imputation to replace the left-censored values.

Validation of CKD and Related Conditions in Existing Data Sets: A Systematic Review

BACKGROUND Accurate classification of individuals with kidney disease is vital to research and public health efforts aimed at improving health outcomes. Our objective is to identify and synthesize published literature evaluating the accuracy of existing data sources related to kidney disease. STUDY DESIGN A systematic review of studies seeking to validate the accuracy of the underlying data relevant to kidney disease. SETTING & POPULATION US-based and international studies covering a wide range of both outpatient and inpatient study populations. SELECTION CRITERIA FOR STUDIES Any English-language study investigating the prevalence or cause of kidney disease, existence of comorbid conditions, or cause of death in patients with chronic kidney disease (CKD). All definitions and stages of CKD, including end-stage renal disease (ESRD), were accepted. INDEX TESTS Presence of a kidney disease-related variable in existing data sets, including administrative data sets and disease registries. REFERENCE TESTS Presence of a kidney disease-related variable defined using laboratory criteria or medical record review. RESULTS 30 studies were identified. Most studies investigated the accuracy of kidney disease reporting, comparing coded renal disease with that defined using estimated glomerular filtration rate. The sensitivity of coded renal disease varied widely (0.08-0.83). Specificity was higher, with all studies reporting values ≥0.90. Studies evaluating the cause of CKD, comorbid conditions, and cause of death in patients with CKD used ESRD or transplant populations exclusively, and accuracy was highly variable compared with ESRD registry data. LIMITATIONS Only English-language studies were evaluated. CONCLUSIONS Given the heterogeneous results of validation studies, a variety of attributes of existing data sources, including the accuracy of individual data items within these sources, should be considered carefully before use in research, quality improvement, and public health efforts.

The university of Michigan dioxin exposure study: Predictors of human serum dioxin concentrations in Midland and Saginaw, Michigan

Background We conducted a population-based human exposure study in response to concerns among the population of Midland and Saginaw counties, Michigan, that discharges by the Dow Chemical Company of dioxin-like compounds into the nearby river and air had led to an increase in residents’ body burdens of polychlorinated dibenzofurans (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs), here collectively referred to as “dioxins.” Objectives We sought to identify factors that explained variation in serum dioxin concentrations among the residents of Midland and Saginaw counties. Exposures to dioxins in soil, river sediments, household dust, historic emissions, and contaminated fish and game were of primary interest. Methods We studied 946 people in four populations in the contaminated area and in a referent population, by interview and by collection of serum, household dust, and residential soil. Linear regression was used to identify factors associated with serum dioxins. Results Demographic factors explained a large proportion of variation in serum dioxin concentrations. Historic exposures before 1980, including living in the Midland/Saginaw area, hunting and fishing in the contaminated areas, and working at Dow, contributed to serum dioxin levels. Exposures since 1980 in Midland and Saginaw counties contributed little to serum dioxins. Conclusions This study provides valuable insights into the relationships between serum dioxins and environmental factors, age, sex, body mass index, smoking, and breast-feeding. These factors together explain a substantial proportion of the variation in serum dioxin concentrations in the general population. Historic exposures to environmental contamination appeared to be of greater importance than recent exposures for dioxins.

Establishing a National Chronic Kidney Disease Surveillance System for the United States

Despite the recognized importance of chronic kidney disease (CKD), the United States currently lacks a comprehensive, systematic surveillance program that captures and tracks all aspects of CKD in the population. As part of its CKD Initiative, the Centers for Disease Control and Prevention (CDC) funded two teams to jointly initiate the development of a CKD surveillance system. Here, we describe the process and methods used to establish this national CDC CKD Surveillance System. The major CKD components covered include burden (incidence and prevalence), risk factors, awareness, health consequences, processes and quality of care, and health system capacity issues. Goals include regular reporting of the data collected, plus development of a dynamic project web site and periodic issuance of a CKD fact sheet. We anticipate that this system will provide an important foundation for widespread efforts toward primary prevention, earlier detection, and implementation of optimal disease management strategies, with resultant increased awareness of CKD, decreased rates of CKD progression, lowered mortality, and reduced resource utilization. Final success will be measured by usage, impact, and endorsement.

Effect of Food Insecurity on Chronic Kidney Disease in Lower-Income Americans

Background: The relation of food insecurity (inability to acquire nutritionally adequate and safe foods) and chronic kidney disease (CKD) is unknown. We examined whether food insecurity is associated with prevalent CKD among lower-income individuals in both the general US adult population and an urban population. Methods: We conducted cross-sectional analyses of lower-income participants of the National Health and Nutrition Examination Survey (NHANES) 2003-2008 (n = 9,126) and the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study (n = 1,239). Food insecurity was defined based on questionnaires and CKD was defined by reduced estimated glomerular filtration rate or albuminuria; adjustment was performed with multivariable logistic regression. Results: In NHANES, the age-adjusted prevalence of CKD was 20.3, 17.6, and 15.7% for the high, marginal, and no food insecurity groups, respectively. Analyses adjusting for sociodemographics and smoking status revealed high food insecurity to be associated with greater odds of CKD only among participants with either diabetes (OR = 1.67, 95% CI: 1.14-2.45 comparing high to no food insecurity groups) or hypertension (OR = 1.37, 95% CI: 1.03-1.82). In HANDLS, the age-adjusted CKD prevalence was 5.9 and 4.6% for those with and without food insecurity, respectively (p = 0.33). Food insecurity was associated with a trend towards greater odds of CKD (OR = 1.46, 95% CI: 0.98-2.18) with no evidence of effect modification across diabetes, hypertension, or obesity subgroups. Conclusion: Food insecurity may contribute to disparities in kidney disease, especially among persons with diabetes or hypertension, and is worthy of further study.

The University of Michigan Dioxin Exposure Study: Population Survey Results and Serum Concentrations for Polychlorinated Dioxins, Furans, and Biphenyls

Background The University of Michigan Dioxin Exposure Study was undertaken to address concerns that the discharge of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo furans (PCDFs) from the Dow Chemical Company in the Midland, Michigan, area had resulted in contamination of soils in the Tittabawassee River floodplain and the city of Midland, leading to an increase in residents’ body burdens of these compounds. Objective In this article we present descriptive statistics from the resident survey and sampling of human serum, household dust, and soil and compare them with other published values. Methods From a multistage random sample of populations in four areas of Midland and Saginaw counties and from a distant referent population, we interviewed 946 adults, who also donated blood for analysis of PCDDs, PCDFs, and polychlorinated biphenyls (PCBs). Samples of household dust and house perimeter soil were collected from consenting subjects who owned their property. Results All five study populations were comparable in age, race, sex, and length of residence in their current home. Regional differences existed in employment history, personal contact with contaminated soils, and consumption of fish and game from contaminated areas. Median soil concentrations were significantly increased around homes in the Tittabawassee River floodplain (11.4 ppt) and within the city of Midland (58.2 ppt) compared with the referent population (3.6 ppt). Median serum toxic equivalencies were significantly increased in people who lived in the floodplain (23.2 ppt) compared with the referent population (18.5 ppt). Conclusions Differences in serum dioxin concentrations among the populations were small but statistically significant. Regression modeling is needed to identify whether the serum concentrations of PCDDs, PCDFs, and PCBs are associated with contaminated soils, household dust, and other factors.

Surveillance of chronic kidney disease around the world: tracking and reining in a global problem.

In recent years, there has been a general recognition of the importance of tackling noncommunicable chronic diseases throughout the world and not just in developed nations. Chronic kidney disease (CKD) is increasingly recognized as a public health threat, based on its high prevalence, rising incidence, associated complications, and cost. It is imperative that nations develop screening and surveillance programs related to CKD. This article provides a global perspective on existing and emerging CKD surveillance efforts. A variety of programs are described, ranging from cross-sectional screening studies to determine CKD prevalence; targeted screening of high-risk populations presenting for voluntary testing; to more systematic surveillance within the scope of integrated health care systems in many developed nations. The choice of surveillance programs for many countries will depend on available resources and competing health care priorities. Integration with surveillance programs for other major chronic diseases such as diabetes, hypertension, and obesity is highly desirable and could be a key to the prevention of CKD. Finally, we propose the model of integrated health systems as one that is perhaps best suited to systematic, longitudinal surveillance of many chronic diseases, a model based on a national electronic health care record with linkage across primary care and hospital-based programs. Robust health education efforts and timely dissemination strategies will remain the key to the success of disease surveillance. It is gratifying to note that more and more countries are developing and adopting CKD surveillance programs as part of national disease prevention strategies.