If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
Persons with chronic kidney disease (CKD) are often unaware of their disease status. Efforts to improve CKD awareness may be most effective if focused on persons at highest risk for progression to kidney failure.
Serial cross-sectional surveys.
Setting & Participants
Nonpregnant adults (aged ≥20 years) with CKD glomerular filtration rate categories 3-4 (G3-G4) who participated in the National Health and Nutrition Examination Survey from 1999 to 2016 (n = 3,713).
5-year kidney failure risk, estimated using the Kidney Failure Risk Equation. Predicted risk was categorized as minimal (<2%), low (2%-<5%), intermediate (5%-<15%), or high (≥15%).
CKD awareness, defined by answering “yes” to the question “Have you ever been told by a doctor or other health professional that you had weak or failing kidneys?”
Prevalence of CKD awareness was estimated within each risk group using complex sample survey methods. Associations between Kidney Failure Risk Equation risk and CKD awareness were assessed using multivariable logistic regression. CKD awareness was compared with awareness of hypertension and diabetes during the same period.
In 2011 to 2016, unadjusted CKD awareness was 9.6%, 22.6%, 44.7%, and 49.0% in the minimal-, low-, intermediate-, and high-risk groups, respectively. In adjusted analyses, these proportions did not change over time. Awareness of CKD, including among the highest risk group, remains consistently below that of hypertension and diabetes and awareness of these conditions increased over time.
Imperfect sensitivity of the “weak or failing kidneys” question for ascertaining CKD awareness.
Among adults with CKD G3-G4 who have 5-year estimated risks for kidney failure of 5%-<15% and ≥15%, approximately half were unaware of their kidney disease, a gap that has persisted nearly 2 decades.
It is generally assumed that awareness of disease is an important stimulus for early preventive care, including minimizing nephrotoxic medication use and guiding treatments to slow kidney disease progression.
To date, studies examining this assumption have failed to show robust associations between CKD awareness and blood pressure control, glycemic control, nonsteroidal anti-inflammatory drug avoidance, and general CKD self-management knowledge and behaviors.
Although these data may temper enthusiasm surrounding diagnostic disclosure of CKD, patient awareness remains an important component of CKD management and preventive care. One argument is that all patients should be aware of all their diagnoses, no matter how consequential, unless they specifically indicate otherwise—and that withholding the diagnosis could represent a paternalistic practice.
In addition, knowledge of CKD diagnosis can reinforce adherence to lifestyle changes and treatments for shared cardiovascular and kidney-related risk factors; patient counseling may be framed in the context of decreasing the risk for worsening kidney function and forestalling or preventing the need for dialysis.
Controversy surrounding the value of CKD awareness is largely due to the uncertainty of whether CKD progression from early to late stages would be prevented if CKD awareness were greater. Although it would be ideal for all persons with CKD to be aware of their condition, CKD awareness is almost certainly most relevant to those at greatest risk for CKD-specific complications, including the need for kidney replacement therapy. The objectives of this study were to estimate CKD awareness in a nationally representative population sample according to risk for progression to kidney failure and to determine whether awareness has changed over time among those with highest risk for progression to kidney failure.
The National Health and Nutrition Examination Survey (NHANES) is a nationally representative cross-sectional survey of noninstitutionalized US civilian residents that has been conducted continuously since 1999 by the Centers for Disease Control and Prevention’s National Center for Health Statistics. The survey obtains cross-sectional prevalence estimates and when combined over multiple years can identify national trends in disease prevalence. NHANES consists of an interview component, a physical examination component, and a laboratory testing component. The NHANES protocol was approved by the National Center for Health Statistics Research Ethics Review Board (protocol #98-12, #2005-06, #2011-17), and informed consent was obtained from all study participants. We examined data from NHANES from 1999 to 2016.
Of the 92,062 NHANES participants in 1999 to 2016, our study population included survey participants 20 years or older and who were not pregnant (remaining n = 48,026). For analyses of CKD awareness, we excluded participants with missing data for age, sex, race, serum creatinine level, or urinary albumin-creatinine ratio (UACR) because this information is required for calculation of estimated glomerular filtration rate (eGFR) and estimation of kidney failure risk (remaining n = 42,106). We excluded participants who did not have CKD GFR categories 3 or 4 (G3-G4), as defined by eGFR ≥ 15 and <60 mL/min/1.73 m2 (remaining n = 3,728). Participants with eGFRs < 15 mL/min/1.73 m2 were excluded due to low sample size (n = 97) and inability to differentiate reliably those receiving dialysis from those with advanced but non–kidney replacement therapy–requiring CKD. Finally, we excluded participants who did not answer “yes” or “no” to the question on awareness of CKD (final n for CKD awareness analysis = 3,713).
CKD G3-G4 was defined by eGFR ≥ 15 and <60 mL/min/1.73 m2, as calculated using the CKD Epidemiology Collaboration (CKD-EPI) equation.
The KFRE is a publicly available risk prediction model initially developed and validated in a retrospective cohort of Canadian patients with CKD; it has demonstrated excellent discriminatory performance in subsequent validation studies using diverse multinational cohorts.
We categorized KFRE-predicted risk into 4 levels: minimal (<2%), low (2-<5%), moderate (5-<15%), and high risk (≥15%). These cutoffs were selected to represent clinically meaningful risk delineations suggested by prior studies.
CKD awareness was defined among those with CKD as a yes answer to the interview question “Have you ever been told that you have weak or failing kidneys? Do not include kidney stones, bladder infections, or incontinence.”
For comorbid conditions, hypertension was defined as either systolic blood pressure ≥ 140 mm Hg, diastolic blood pressure ≥ 90 mm Hg, or current use of antihypertensive medication.
If more than 1 blood pressure reading was measured, mean systolic and diastolic values across all readings were used. Diabetes was defined as hemoglobin A1c level ≥ 6.5% or current use of diabetes medication.
Combining all survey years 1999 to 2016, the proportion of persons aware of CKD was estimated within each risk group. To assess for temporal trends, we examined CKD awareness during 3 consecutive 6-year intervals: 1999 to 2004, 2005 to 2010, and 2011 to 2016. Multiple survey years were aggregated to ensure sufficient cell sizes for analysis within each interval and KFRE risk group. The unadjusted prevalence of CKD awareness was estimated during each interval by KFRE risk group. Temporal trends in CKD awareness were assessed by fitting logistic regression models using interval as a categorical predictor, then using contrasts to test for linear trends in the corresponding coefficients.
The association between KFRE risk and CKD awareness was examined using multivariable logistic regression, adjusting for demographic variables and comorbid conditions previously associated with CKD awareness. Because the question of whether CKD definition should use an age-adapted eGFR is an issue of current interest,
we also examined whether the association between KFRE risk and CKD awareness varied by age. For this analysis, age was categorized as 20 to 64, 65 to 74, and 75 or more years. Using logistic regression with an interaction term for age and KFRE risk, marginal predictions of CKD awareness were obtained for each KFRE risk group according to age category.
As a secondary analysis, we compared awareness of CKD with awareness of other common chronic conditions, namely, hypertension and diabetes. For this analysis, hypertension awareness was defined as either self-reported hypertension (defined by answering yes to the question “Have you ever been told by a doctor or other health professional that you had hypertension, also called high blood pressure?”) or self-reported use of prescription medication for high blood pressure among persons with hypertension. Diabetes awareness was defined as either self-reported diabetes (defined by answering yes to the question “Other than during pregnancy, have you ever been told by a doctor or health professional that you have diabetes or sugar diabetes?”) or self-reported insulin or diabetic pill use among persons with diabetes.
Analyses were performed using Stata/IC, version 15.1 (StataCorp). Adjustments were made to account for historical laboratory creatinine calibration issues according to NHANES analytical guidelines (Item S2). All estimates in NHANES were weighted to the US population using the appropriate sample weights with variance computed accounting for strata and primary sampling units. All reported estimates were based on >8 df, and all had relative standard error < 30%, in accordance with NHANES analytic guidelines and the National Center for Health Statistics Data Presentation Standards for Proportions.
Baseline characteristics of NHANES participants with CKD G3-G4 (n = 3,713) are described in Table 1. Higher KFRE risk was more common among men, persons of nonwhite race/ethnicity, persons with diabetes, and persons with hypertension. Mean eGFR ranged from 52 mL/min/1.73 m2 in the minimal KFRE risk group to 26 mL/min/1.73 m2 in the highest risk group; median UACR ranged from 9 to 934 mg/g across these groups of KFRE risk. The proportion of persons with any type of health insurance was high at ∼96% and was similar across all risk groups, although in higher risk groups, Medicaid was more common (14.4% in the highest risk group vs 6.6% in the lowest) and private insurance was less common (48.9% vs 61.2%, respectively).
Table 1Characteristics of US adults With CKD by Estimated 5-Year Kidney Failure Risk, NHANES 1999-2016
Note: Values in parentheses are 95% confidence intervals. Reported figures are adjusted for complex survey design used by NHANES to estimate nationally representative results. Obesity defined as body mass index ≥ 30 kg/m2.
Abbreviations: CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate, calculated by Chronic Kidney Disease–Epidemiology Collaboration (CKD-EPI) equation; NHANES, National Health and Nutrition Examination Survey; UACR, urinary albumin-creatinine ratio.
Among adults with CKD G3-G4 and <2% KFRE risk, 7.0% (95% confidence interval [CI], 5.9%-8.3%) were aware of their CKD; among those with 2%-<5% KFRE risk, 18.7% (95% CI, 14.0%-23.4%) were aware; among those with 5%-<15% KFRE risk, 43.4% (95% CI, 36.4%-50.5%) were aware; and among those with ≥15% KFRE risk, 49.6% (95% CI, 41.1%-58.2%) were aware.
Consistently over time, crude prevalence of CKD awareness was higher with higher KFRE risk group (Fig 1A). In analyses of awareness over time, unadjusted analyses showed a borderline statistically significant trend only among those at minimal KFRE risk (6.3% [95% CI, 4.3%-8.3%] in 1999-2004 and 9.6% [95% CI, 7.4%-11.8%] in 2011-2016; Ptrend = 0.03). In other KFRE risk groups, no statistically significant trends were found: CKD awareness estimates in the 2%-<5% KFRE risk group were numerically higher in 2011 to 2016 (22.6%; 95% CI, 14.7%-30.4%) than in 1999 to 2004 (14.6%; 95% CI, 6.6%-22.5%), but this was not statistically significant (Ptrend = 0.2). Awareness in higher risk groups ranged from 42% to 50% (Ptrend = 0.8 and 0.9, respectively).
Similar results were obtained when analyses were conducted for direct age-standardized CKD awareness (Fig 1B) and then with adjustment for sex, age, race/ethnicity, presence of hypertension, and presence of diabetes (Fig 1C). No statistically significant trends were observed in any KFRE risk groups in either age-standardized or adjusted analyses.
Association of Kidney Failure Risk With CKD Awareness
The association between KFRE risk and CKD awareness was examined using multivariable logistic regression (Table 2). In both unadjusted and adjusted models, the odds of CKD awareness were greater with each category of higher KFRE risk. Odds of CKD awareness were similar in the 2 highest risk groups (5%-<15% and ≥15%). Associations between CKD awareness and each KFRE risk group were all statistically significant (P < 0.01 for each).
Table 2Association of Kidney Failure Risk and CKD Awareness by Multivariable Logistic Regression Among US Adults With CKD G3-G4
Figure 2 shows unadjusted and adjusted CKD awareness by KFRE risk and age categories. Findings were overall similar between unadjusted and adjusted analyses. CKD awareness was greater with increasing kidney failure risk, except among the highest risk group in the 20- to 64-year age category. The 75-year-or-older age category consistently had the lowest awareness across all risk groups. Of note, interpretation of these interactions is limited due to wide CIs, and P values for interaction were nonsignificant in both unadjusted and adjusted analyses.
Comparison of Awareness of CKD, Hypertension, and Diabetes
Figure 3 shows trends in awareness of diabetes and hypertension during the study period compared with CKD (all CKD G3-G4) and high-risk CKD (CKD with ≥15% risk for kidney failure at 5 years as determined by the KFRE). From 1999 to 2016, hypertension and diabetes awareness were both consistently higher than CKD awareness in all CKD G3-G4 and in high-risk CKD. During this period, both hypertension and diabetes exhibited an increase in prevalence of disease awareness (Ptrend < 0.001 for both).
In this nationally representative sample of US adults, we found that although CKD awareness was higher among persons with higher 5-year kidney failure risk, approximately half the participants with ≥15% risk for developing kidney failure within 5 years were unaware of having kidney disease. Additionally, no statistically significant trends over time were observed in CKD awareness for any risk groups except among those with minimal-risk CKD, but this trend was not significant in adjusted analyses. After adjustment for demographic factors and comorbid conditions, we found that higher predicted kidney failure risk was associated with increased odds of CKD awareness.
Our findings that CKD awareness is markedly lower for persons with CKD, even those at the highest levels of risk for kidney failure, compared with all persons with hypertension or diabetes regardless of their future risk for adverse events underscore the need for the Public Awareness Initiative for Advancing American Kidney Health launched by the National Kidney Foundation, American Society of Nephrology, and US Department of Health and Human Services.
This initiative aims to elevate kidney disease awareness and includes an accompanying Kidney Risk Campaign. Additionally, both diabetes and hypertension awareness demonstrate an increase over time with statistically significant Ptrend values. The trend in awareness for CKD G3-G4 was not significant in adjusted analyses. Furthermore, no statistically significant trends were observed in the high-risk CKD group, a group for whom the practical implications of CKD are potentially most clinically relevant.
There are several possible factors contributing to low CKD awareness. In one study of audiotaped primary care encounters, CKD was less commonly discussed compared with hypertension or diabetes, and most CKD discussions were limited to technical discussion of laboratory results rather than risk factors, prevention, or complications.
Other possible contributing factors may be provider underrecognition, lack of CKD knowledge or familiarity on the part of primary care providers, and fear of overwhelming patients, as compared with hypertension or diabetes.
A somewhat surprising finding was the similarity in CKD awareness between the intermediate- (5%-<15% KFRE risk at 5 years) and high-risk (≥15%) groups. Both categories of risk were associated with approximately 9 times the odds of awareness compared with the minimal-risk group. The decision not to disclose CKD to patients has been attributed at least in part to the view that there is little benefit to CKD disclosure when kidney disease is mild, has no immediate treatment implications, and is likely to cause undue anxiety in patients who are worried they will need dialysis or kidney transplantation.
If clinicians’ efforts to notify and educate patients about CKD are related to kidney disease severity, similar rates of awareness between intermediate and high levels of risk would suggest that clinicians are failing to discriminate between these levels of risk in patients with CKD.
Although persons in the highest risk group had a mean eGFR that was 7 mL/min/1.73 m2 lower than those in the intermediate-risk group (33 vs 26 mL/min/1.73 m2), they had substantially more albuminuria (median UACRs of 934 vs 63 mg/g). Prior studies have shown proteinuria to be an uncommon reason for nephrology referral, suggesting that a possible reason that clinicians fail to recognize high-risk kidney disease may be a relative underappreciation of the prognostic significance of albuminuria compared to eGFR for predicting renal and cardiovascular outcomes.
Risk assessment using KFRE would reinforce the importance of albuminuria measurement and allow clinicians to assess risk more effectively and objectively for patients with CKD. KFRE use in primary care could help risk-stratify patients with CKD and inform appropriate counseling, as well as next steps in workup and referral.
We found no statistically significant effect modification of age on the association between KFRE risk and CKD awareness. Except in the highest KFRE risk group, CKD awareness was higher in younger age groups. Of the multiple provider-level (recognition and disclosure) and patient-level (eg, health literacy and denial) factors that may affect awareness, the observed findings are suggestive of several possibilities.
One possible provider-level factor would be a higher threshold for disclosure for mild CKD at older age. This may be due to a view that kidney disease is a part of normal aging and that labeling or disclosure may lead to undue anxiety and stigma for otherwise well patients.
This behavior, regardless of whether intentional, is much in keeping with the recent conversation surrounding whether the eGFR-based definition of CKD should be age-adapted, based on physiologic age-related kidney function decline and examination of age-dependent differences in mortality risk associated with eGFR.
In particular, it has been suggested that the threshold eGFR for CKD definition should be higher with younger age (75 mL/min/1.73 m2 for age < 45 years) and lower with older age (45 mL/min/1.73 m2 for age > 65 years).
Another possibility is whether providers are underrecognizing CKD in older age groups, which is plausible if older individuals are more likely to have creatinine tested for reasons other than kidney health, thereby leading to incidental detection of CKD. Additional study would be needed to discern the extent to which age-related differences in provider recognition versus disclosure (vs patient-level factors) lead to different rates of CKD awareness. However, these findings should be interpreted with caution given the uncertainty associated with awareness estimates due to small sample sizes in higher KFRE risk groups.
This study benefits from capturing a nationally representative population over an extended period spanning 18 years. It also represents use of the KFRE as a method to stratify our analysis based on each person’s risk for a meaningful clinical outcome, rather than stratifying by disease definitions such as CKD stage or albuminuria, which are not as directly patient-centered. Our study examined the CKD population through a lens of predicted risk rather than observed outcomes, providing a more coherent and actionable framework for guiding CKD awareness efforts and focusing on persons at high risk for kidney failure. By directly showing low awareness among persons with high predicted kidney failure risk, we define a discrete population—identifiable based on presently obtainable laboratory and demographic information—in which awareness efforts may be intensified. As the basis for risk-based care, this helps further underscore the importance of albuminuria testing for risk stratification to guide referral, counseling, and treatment decisions.
The primary limitation of this study was the imperfect sensitivity of the question used in NHANES for ascertaining awareness of kidney disease. Ascertainment of CKD awareness among persons with laboratory-defined CKD can differ according to how the question is asked, with the NHANES question referring to “weak or failing kidneys” being relatively less sensitive compared with different phrases to describe CKD.
Clinicians may describe CKD to patients in a variety of ways (eg, weak kidneys, kidney disease, poor kidney function, and protein in the urine), and the best question to ascertain CKD awareness has not been conclusively established. A study has shown that a compound question or combining multiple questions may increase the yield.
However, the present question remains the most readily available way to obtain consistent nationally representative estimates of trends in CKD awareness. Given that improving awareness of kidney disease has been announced in 2019 as a priority of the Advancing American Kidney Health initiative, better validated tools are needed for improved measurement and national surveillance of CKD awareness.
Additional limitations included small numbers of persons with advanced CKD, which precluded more precise estimation and analysis of CKD awareness in higher risk groups. Because of the cross-sectional nature of NHANES, the diagnosis of CKD was based on a single measurement of creatinine and albuminuria, whereas the gold-standard definition requires 2 abnormal laboratory parameters separated by at least 3 months.
Similarly, hypertension and diabetes diagnoses may be subject to misclassification due to definitions based on a single time point. Finally, the cross-sectional design does not allow any inference with respect to whether or how kidney failure risk might lead to CKD awareness.
In summary, we found in a nationally representative sample that approximately half the persons with CKD and high risk for progression to kidney failure (≥15% within 5 years) were unaware of having kidney disease, and among those with minimal (<2%) risk, <10% were aware. The heterogeneity of kidney failure risk also likely contributes to difficulty demonstrating the effects of CKD awareness in the overall CKD population. Future studies of CKD awareness should present risk-stratified results because this may better direct public health efforts. Although there may be some debate about the disclosure of CKD diagnosis for those with milder degrees of CKD and low risk for progression, the finding that such a large proportion of persons with the highest risk for needing dialysis or kidney transplantation within 5 years is unaware of having kidney disease is highly concerning, particularly because awareness in this group remains below that of hypertension and diabetes and has not changed with time. Despite broadly directed efforts by many organizations to raise overall awareness of kidney disease over the years, CKD awareness has remained largely unchanged for 18 years. The 2019 executive order on Advancing American Kidney Health initiative was an unprecedented step in garnering nationwide attention surrounding kidney disease, bringing it directly into the national spotlight. The subsequent announcement of the Public Awareness Initiative, which is to include a nationwide Kidney Risk Campaign, is an exciting and welcome step we should all look forward to with great anticipation.
CDC CKD Surveillance Team
University of Michigan: Rajiv Saran (PI), Vahakn Shahinian, Michael Heung, Brenda W. Gillespie, Hal Morgenstern, William Herman, Kara Zivin, Jennifer Bragg-Gresham, Diane Steffick, Yun Han, Xiaosong Zhang, Yiting Li, Vivian Kurtz, April Wyncott; University of California, San Francisco: Neil R. Powe (PI), Tanushree Banerjee, Delphine S. Tuot, Chi-yuan Hsu, Charles E. McCulloch, Deidra Crews, Raymond Hsu, Kirsten Johansen, Michael Shlipak, Janet Canela; Centers for Disease Control and Prevention: Nilka Ríos Burrows (Technical Advisor), Mark Eberhardt, Juanita Mondesire, Priti Patel, Meda Pavkov, Deborah Rolka, Sharon Saydah, Sundar Shrestha, Larry Waller.
Authors’ Full Names and Academic Degrees
Chi D. Chu, MD, Charles E. McCulloch, PhD, Tanushree Banerjee, PhD, Meda E. Pavkov, MD, PhD, Nilka R. Burrows, MPH, Brenda W. Gillespie, PhD, Rajiv Saran, MD, Michael G. Shlipak, MD, MPH, Neil R. Powe, MD, MPH, MBA, and Delphine S. Tuot, MDCM, MAS.
Research idea and study design: CDC, TB, MEP, NRB, BWG, RS, MGS, DST, NRP; data acquisition: CDC; data analysis/interpretation: CDC, CEM, DST; statistical analysis: CDC, CEM, DST; supervision or mentorship: DST, NRP. Each author contributed important intellectual content during manuscript drafting or revision, accepts personal accountability for the author’s own contributions, and agrees to ensure that questions pertaining to the accuracy or integrity of any portion of the work are appropriately investigated and resolved.
This investigation was supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under the Ruth L. Kirschstein National Research Service Award 1F32DK122629-01, and by the Supporting, Maintaining and Improving the Surveillance System for Chronic Kidney Disease in the U.S., Cooperative Agreement Number, U58 DP006254 , funded by the Centers for Disease Control and Prevention . The funders of this study had no role in study design; collection, analysis, and interpretation of data; writing the report; and the decision to submit the report for publication.
The authors declare that they have no relevant financial interests.
The findings and conclusions in this report are solely those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the Department of Health and Human Services.
An earlier version of this work was presented as a poster at the American Society of Nephrology Kidney Week, November 5-10, 2019, Washington, DC.
Received September 19, 2019. Evaluated by 2 external peer reviewers and a statistician, with direct editorial input from an International Editor, who served as Acting Editor-in-Chief. Accepted in revised form January 6, 2020. The involvement of an Acting Editor-in-Chief was to comply with AJKD’s procedures for potential conflicts of interest for editors, described in the Information for Authors & Journal Policies.