CDC Surveillance System: Awareness of CKD Among U.S. Adults with Albuminuria

Percentage with Albuminuria or eGFR > 15 Who Were Aware of Their Disease^a by eGFR and Albuminuria For 1999–2016 National Health and Nutrition Examination Survey
Albuminuria	eGFR >90	eGFR 60–89	eGFR 45–59	eGFR 30–44	eGFR 15–29
Microalbuminuria	3.0 (CI 1.9-4.1)	5.4 (CI 3.8-7.0)	9.5 (CI 6.2-12.8)	23.8 (CI 18.8-28.7)	54.6 (CI 45.7-63.5)
Macroalbuminuria	7.8 (CI 5.3-10.2)	12.4 (CI 7.2-17.6)	16.7 (CI 10.0-23.5)	39.4 (CI 30.7-48.1)	52.5 (CI 41.0-64.1)
All	3.5 (CI 2.5-4.5)	6.3 (CI 4.8-7.8)	11.0 (CI 8.0-13.9)	28.1 (CI 23.6-32.6)	53.6 (CI 46.3-60.8)

Footnotes:
^a Albuminuria defined by albumin:creatinine ratio obtained from spot urine sample: microalbuminuria, 30-299 mg/g; macroalbuminuria, ≥300 mg/g.

In 1999-2016, <10% of those with eGFR ≥60 ml/min/1.73 m² with albuminuria (single random measurement) were aware of having CKD. Reported awareness was estimated to be higher for those with stage 3B (eGFR 30-44) at 28% compared to those with CKD stage 3A (eGFR 45-59) at 11%. For stage 4 (eGFR 15-29), 53.6% reported being aware of their disease.

Those with evidence of albuminuria, particularly an albumin:creatinine ratio ≥300 mg/g (macroalbuminuria), were generally more likely to be aware of their CKD condition (15% in 2005-2010 to 20% in 2011-2016).

Chart Explanation:

As expected, awareness increased with severity or stage of CKD. However, half of participants (53.6%) with stage 4 - the most severe stage prior to end-stage renal disease - reported being told by their physician that they had weak or failing kidneys. Fewer than 40% of stage 3 participants were aware of their disease, although the proportion was substantially higher for those with eGFR 30-44 than those with eGFR 45-59 ml/min/1.73 m² (28.1% vs. 10.9%). Among those with eGFR <90 and >30 ml/min/1.73 m², macroalbuminuria versus microalbuminuria was associated with greater awareness. For example, among those with eGFR 30-44 ml/min/1.73 m², awareness was 23.8% among those with microalbuminuria, while 39.4% of those with macroalbuminuria reported being aware, respectively.

In observance of albuminuria over time, microalbuminuria remained low with 5.6% reporting awareness in 1999-2004 to 7.4% in 2011-2016. As noted, awareness was more likely in those with macroalbuminuria (20.2% in 1999-2004 to 20.3% in 2011-2016). The trends for reported awareness of CKD were significant for microalbuminuria whereas for macroalbuminuria, no significant trends were noted.

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 and blood and urine collection at a mobile examination center (MEC). Here we examined data from the 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, 2013-2014, and 2015-2016 NHANES. Awareness of CKD was defined as a “yes” response to the question “Have you ever been told by a health care provider you have weak or failing kidneys (excluding kidney stones, bladder infections, or incontinence)?” during the interview. CKD was diagnosed by laboratory testing and defined as an eGFR of ≥60 ml/min/1.73 m² and the presence of albuminuria (first single measurement of albumin: creatinine ratio from random spot urine) or by eGFR alone for CKD stage 3 or 4 (stage 5 was excluded).

Field	Data
Description of Measure	Awareness of CKD among those with kidney disease diagnosed by laboratory testing
Data Source	NCHS
Type of Data Source	Public
Data Set	NHANES
Health Care System Data	No
Regional or National?	National
Demographic Group	Non-institutionalized U.S. residents aged 20+ years
Numerator	Participants with CKD who have been told they have weak or failing kidneys
Denominator	Participants with CKD
Definition of CKD	Stage 1, eGFR > 90 ml/min/1.73 m² and presence of single albuminuria; Stage 2, eGFR 60-89 ml/min/1.73 m² and presence of single albuminuria; Stage 3, eGFR 30-59 ml/min/1.73 m²; Stage 4, 15-29 ml/min/1.73 m²; Stage 5, excluded
Glomerular filtration rate	Estimated using CKD-EPI equation for calibrated creatinine: eGFR=141 x [min(calibrated serum creatinine in mg/dL) /κ, 1)]^α x [max(calibrated serum creatinine in mg/dL/κ, 1)]^κ x 0.993^age x (1.018 if female) x (1.159 if NH Black) κ = 0.7 if female, and 0.9 if male α = -0.329 if female, and -0.411 if male
Proteinuria	Urinary albumin-to-creatinine ratios of 30-299 mg/g (microalbuminuria) and >300 mg/g (macroalbuminuria); pregnant/menstruating women excluded
Primary Data Source Indicator	kiq022/kiq010: “Have you ever been told by a doctor or health professional that you have weak or failing kidneys (excluding kidney stones, bladder infections, or incontinence)?” yes/no
Primary Indicator Method of Measurement	Questionnaire (interviewer-administered)
Secondary (1) Variable	lbxscr: Serum creatinine
Secondary (1) Indicator Method of Measurement	Examination/Laboratory
Secondary (2) Variable	ridageyr: Age in years
Secondary (2) Indicator Method of Measurement	Questionnaire (interviewer-administered)
Secondary (3) Variable	ridgendr: Gender
Secondary (3) Indicator Method of Measurement	Questionnaire (interviewer-administered)
Secondary (3) from Medical Record?	No
Secondary (4) Data Source Indicator	ridreth1: Race/ethnicity
Secondary (4) Indicator Method of Measurement	Questionnaire (interviewer-administered)
Secondary (5) Data Source Indicator	urxuma: Urine albumin
Secondary (5) Indicator Method of Measurement	Examination/lab
Secondary (5) Data Source Indicator	urxucr: Urine creatinine
Secondary (5) Indicator Method of Measurement	Examination/lab
Frequency of Measurement (Primary)	Once (cross-sectional)
U.S. Region Covered by Primary Variable	All
Period Currently Available	1999–2016
Pending Data	2017-2018
Additional Data Items of Interest	Stage of CKD, year, other stratification variables of interest (diabetes by self-report, hypertension by self-report)
Limitations of Indicator	Proteinuria can only be assessed from a one-time cross-sectional measurement in 1999-2008; two measurements only in 2009-2010, including first random and second first-morning void ~2 weeks after MEC exam; participants who have been told they have proteinuria may not answer yes
Analytic Considerations	Appropriate NHANES survey weights must be used for all analyses; creatinine measurements must be calibrated for NHANES years 1999-2000 and 2005-2006; if 2007-2008 data are combined with 1999-2006 data, the earlier data on urinary creatinine must be corrected; many variable names differ across surveys; if SE 30% or more of estimate, must suppress estimates and report as “low precision”; second urine albumin and creatinine measurements only available in 2009-2010 and not for 2011+

Suggested Citation:

Centers for Disease Control and Prevention. Chronic Kidney Disease Surveillance System—United States.
website. http://www.cdc.gov/ckd