Chronic kidney disease in US adults with type 2 diabetes: an updated national estimate of prevalence based on Kidney Disease: Improving Global Outcomes (KDIGO) staging

Bailey et al. BMC Research Notes 2014, 7:415 http://www.biomedcentral.com/1756-0500/7/415 RESEARCH ARTICLE Open Access Chronic kidney disease in US adults with type 2 diabetes: an updated national estimate of prevalence based on Kidney Disease: Improving Global Outcomes (KDIGO) staging Robert A Bailey1*, Yiting Wang2, Vivienne Zhu2 and Marcia FT Rupnow1 Abstract Background: Kidney Disease Improving Global Outcomes (KDIGO) 2013 updated the classification and risk stratification of chronic kidney disease (CKD) to include both the level of renal function and urinary albumin excretion (UAE). The update subclassifies the previous category of moderate renal impairment. There is currently limited information on the prevalence of CKD based on this new classification in United States (US) adults with type 2 diabetes mellitus (T2DM). The objective of this study was to provide such estimates, for T2DM both overall and in those ≥ 65 years of age. We used the continuous National Health and Nutrition Examination Survey (NHANES) 1999–2012 to identify participants with T2DM. Estimated glomerular filtration rate (eGFR) and UAE were calculated using laboratory results and data collected from the surveys, and categorized based on the KDIGO classification. Projections for the US T2DM population were based on NHANES sampling weights. Results: A total of 2915 adults diagnosed with T2DM were identified from NHANES, with 1466 being age ≥ 65 years. Prevalence of CKD based on either eGFR or UAE was 43.5% in the T2DM population overall, and 61.0% in those age ≥ 65 years. The prevalence of mildly decreased renal function or worse (eGFR < 60/ml/min/1.73 m2) was 22.0% overall and 43.1% in those age ≥ 65 years. Prevalence of more severe renal impairment (eGFR < 45 ml/min/1.73 m2) was 9.0% overall and 18.6% in those age ≥ 65 years. The prevalence of elevated UAE (> 30 mg/g) was 32.2% overall and 39.1% in those age ≥ 65 years. The most common comorbidities were hypertension, retinopathy, coronary heart disease, myocardial infarction, and congestive heart failure. Conclusions: This study confirms the high prevalence of CKD in T2DM, impacting 43.5% of this population. Additionally, this study is among the first to report US prevalence estimates of CKD based on the new KDIGO CKD staging system. Keywords: Diabetes, Type 2 diabetes mellitus, Chronic kidney disease, Prevalence, Estimated glomerular filtration rate, Albuminuria Background Type 2 diabetes mellitus (T2DM) is the leading cause of chronic kidney disease (CKD) in the United States (US), with previous estimates suggesting close to 40% of patients with T2DM having evidence of CKD [1]. Concordant with the high prevalence of CKD in this population, diabetes was attributed as the cause of end-stage renal disease (ESRD) in 44.2% of incident dialysis patients in 2011 [2]. * Correspondence: 1 Janssen Scientific Affairs, LLC, 1000 Route 202 South, Raritan, NJ 08869, USA Full list of author information is available at the end of the article The high burden of CKD in T2DM and the associated adverse outcomes result in high health-care costs to both public and private payers [2,3]. Based on the significant impact of CKD, Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease: Improving Global Outcomes (KDIGO) recommend a focus on early identification of CKD. This early identification may allow for treatment directed at CKD to slow or prevent progression, and treatment of associated complications and comorbidities such as cardiovascular disease [4,5]. © 2014 Bailey et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Bailey et al. BMC Research Notes 2014, 7:415 http://www.biomedcentral.com/1756-0500/7/415 KDOQI originally proposed a uniform CKD staging and classification system based on estimated glomerular filtration rate (eGFR) [5]. The original classification ranged from Stage 1 CKD (defined as normal kidney function with other markers for kidney damage) to Stage 5 CKD (defined as kidney failure). This staging system served to provide clinicians with stage-specific action plans for treatment of CKD and associated comorbidities and complications. Additionally, this staging system facilitated research and served as a framework for developing a public-health approach to CKD. Soon after the original KDOQI CKD staging system was published, Go et al. [6] reported that although the risk for death, cardiovascular disease, and hospitalizations increased when eGFR declined below 60 ml/min/1.73 m2 (Stage 3 CKD), these risks substantially increased when eGFR declined below 45 ml/min/1.73 m2 [6]. Based on this evidence, Go et al. advocated for subclassification of Stage 3 to reflect these findings. A recent meta-analysis provided further evidence to support the division of Stage 3 CKD into 3a and 3b based on the increased risk for progression to ESRD, and cardiovascular and all-cause mortality at the GFR threshold of < 45 ml/min/m2 [7,8]. Based on this new evidence, developed since KDOQI, KDIGO recently updated the classification system for CKD [4]. This new classification system is based on the cause of CKD, gFR category, and albuminuria category (CGA). The cause category is based on the presence or absence of systemic disease. The GFR categories acknowledge the need to subdivide Stage 3 CKD, classified as G3 under the new classification system, into G3a (eGFR 45– 59) and G3b (eGFR 30–44). The albuminuria categories are based on the presence and severity of albuminuria. This new classification was developed to allow risk stratification based on progression of CKD and cardiovascular and all-cause mortality. The prevalence of diabetes in the older adult population (age > 65) is greater than 20%. This older adult group also has a higher prevalence of comorbid conditions (such hypertension, cardiovascular disease, and CKD) compared to younger populations [2,9]. Based on these specific considerations in the older adult population, the American Diabetes Association (ADA) recommends a different approach in this population. These specific recommendations include potentially less stringent treatment targets and special consideration in the selection of antihyperglycemic agents. To date, there are no US estimates of the prevalence of CKD in T2DM based on this new classification system, particularly for stages G3a and G3b. The objective of this study was to provide current national estimates of the prevalence of CKD in the overall T2DM population, and in the subpopulation aged ≥ 65 years using this new KDIGO classificat (...truncated)