The National Health and Nutrition Examination Survey (NHANES) is a nationally representative, cross-sectional survey that is currently conducted every 2 years by the Centers for Disease Control and Prevention's National Center for Health Statistics to examine disease prevalence and trends over time in noninstitutionalized U.S. civilian residents.
The survey consists of a standardized in-home interview and a physical examination with blood and urine collected at a mobile examination center (MEC). Here, we examined data from the 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, 2013-2014, 2015-2016, and 2017- March 2020 NHANES. Estimated glomerular filtration rate (eGFR) was calculated according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for calibrated creatinine (Levey et al., 2009). Serum creatinine was calibrated for 1999-2000 and 2005-2006 participants; no correction was required for calibrated serum creatinine in participants in the 2001-2002, 2003-2004, 2007-2008, 2009-2010, 2011-2012, 2013-2014, and 2015-2016 surveys (Selvin et al., 2007). Albuminuria was defined by urinary albumin-to-creatinine ratio ≥30 mg/g; moderate albuminuria ranges between 30 and 299 mg/g and severe albuminuria is ≥300 mg/g; pregnant women were excluded. For comparisons across the 18-year period 1999-2016, albuminuria was corrected in 1999-2006 to account for differences in the instrumentation and method for urine creatinine starting in 2007. Prevalence of CKD is likely overestimated by single measurements of albuminuria and kidney function (eGFR). In clinical practice, CKD is defined by persistent albuminuria or reduced kidney function for ≥3 months.