1/6/2021 Annual Data Report | USRDS localhost:3000/2020/chronic-kidney-disease/1-ckd-in-the-general-population 1/24 Chronic Kidney Disease: Chapter 1 CKD in the General Population Highlights Overall, 14.9% of the U.S. adult population surveyed in 2015-2018 had CKD based on a low eGFR or proteinuria (on a single examination), a percentage that has been relatively stable over the last several years (Table 1.1). The distribution of CKD stages has shifted slightly, with an increase in albuminuria (i.e., CKD stages 1- 2) and a slight reduction in CKD stage 3, particularly among older individuals (Figure 1.1). The prevalence of CKD declined within several key risk groups, including older individuals and those with diabetes, hypertension, and cardiovascular disease (Figure 1.5). However, the prevalence of these risk factors increased over the same period (Figure 1.6). Thus, some success in prevention of CKD among high-risk individuals was offset by an increase in the number of individuals with these underlying high-risk conditions. Although individuals with CKD were more likely to be sedentary than those without CKD (35.2% vs. 24.5% in 2015-2018) (Figure 1.7), this difference decreased over the time, driven mostly by improvement among individuals with CKD. The percentage of adults with CKD whose blood pressure was <130/80 mmHg improved over time, from 41.3% in 2003-2006 to 45.7% in 2015-2018 (Figure 1.8). However, glycemic control worsened among individuals with diabetes and CKD from 2003-2006 to 2015-2018, although there was some improvement in 2015-2018 compared with 2011-2014 (Figure 1.10). Introduction and Methods This chapter presents cross-sectional estimates of CKD prevalence in the United States using data from the National Health and Nutrition Examination Survey, which includes data derived from interviews, physical examinations, and laboratory testing. The sample, which is updated biennially, is representative of the non- institutionalized U.S. population, with oversampling of certain subgroups to increase reliability and precision of health indicator estimates. We report the most recent NHANES results for 2017-2018, which became available in February of 2020, and examine trends based on four distinct four-year periods — 2003-2006, 2007-2010, 2011-2014, and 2015-2018. The study population consists of 39,569 NHANES participants aged ≥20 years with serum creatinine and urinary albumin and creatinine measures, 9901 of whom are members of the 2015-2018 cohort. In its 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (Kidney Disease: Improving Global Outcomes CKD Workgroup, 2013), KDIGO defined CKD as abnormalities of kidney structure or function present for >3 months with implications for health. These KDIGO guidelines classified CKD based on cause, GFR category, and albuminuria category and then grouped GFR and albuminuria categories into risk categories for CKD-related outcomes. We have estimated CKD stages and risk categories based on single estimates of GFR and albuminuria available in NHANES, which invariably overestimates the prevalence of CKD compared with a requirement for persistently abnormal values in the clinical practice guidelines. We evaluated kidney function using eGFR
Overall, 14.9% of the U.S. adult population surveyed in 2015-2018 had CKD based on a low eGFR orproteinuria (on a single examination), a percentage that has been relatively stable over the last severalyears (Table 1.1).
The distribution of CKD stages has shifted slightly, with an increase in albuminuria (i.e., CKD stages 1-2) and a slight reduction in CKD stage 3, particularly among older individuals (Figure 1.1).
The prevalence of CKD declined within several key risk groups, including older individuals and thosewith diabetes, hypertension, and cardiovascular disease (Figure 1.5). However, the prevalence of theserisk factors increased over the same period (Figure 1.6). Thus, some success in prevention of CKDamong high-risk individuals was offset by an increase in the number of individuals with these underlyinghigh-risk conditions.
Although individuals with CKD were more likely to be sedentary than those without CKD (35.2% vs.24.5% in 2015-2018) (Figure 1.7), this difference decreased over the time, driven mostly byimprovement among individuals with CKD.
The percentage of adults with CKD whose blood pressure was <130/80 mmHg improved over time,from 41.3% in 2003-2006 to 45.7% in 2015-2018 (Figure 1.8). However, glycemic control worsenedamong individuals with diabetes and CKD from 2003-2006 to 2015-2018, although there was someimprovement in 2015-2018 compared with 2011-2014 (Figure 1.10).
Introduction and MethodsThis chapter presents cross-sectional estimates of CKD prevalence in the United States using data from theNational Health and Nutrition Examination Survey, which includes data derived from interviews, physicalexaminations, and laboratory testing. The sample, which is updated biennially, is representative of the non-institutionalized U.S. population, with oversampling of certain subgroups to increase reliability and precisionof health indicator estimates. We report the most recent NHANES results for 2017-2018, which becameavailable in February of 2020, and examine trends based on four distinct four-year periods — 2003-2006,2007-2010, 2011-2014, and 2015-2018. The study population consists of 39,569 NHANES participantsaged ≥20 years with serum creatinine and urinary albumin and creatinine measures, 9901 of whom aremembers of the 2015-2018 cohort.
In its 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease(Kidney Disease: Improving Global Outcomes CKD Workgroup, 2013), KDIGO defined CKD asabnormalities of kidney structure or function present for >3 months with implications for health. TheseKDIGO guidelines classified CKD based on cause, GFR category, and albuminuria category and thengrouped GFR and albuminuria categories into risk categories for CKD-related outcomes. We haveestimated CKD stages and risk categories based on single estimates of GFR and albuminuria available inNHANES, which invariably overestimates the prevalence of CKD compared with a requirement forpersistently abnormal values in the clinical practice guidelines. We evaluated kidney function using eGFR
calculated using the CKD-EPI creatinine equation (Levey et al., 2009), and we used the urinary albumin tocreatinine ratio (ACR) to assess urinary albumin excretion. In NHANES, diabetes mellitus and hypertensionare defined using patient report, examination or laboratory testing, and medication use, whereascardiovascular disease is based on self-report only as hospital records were not available.
Because NHANES does not provide data at the state level, we also examine data on the prevalence of self-reported kidney disease by state using data from the Behavioral Risk Factors Surveillance System (Centersfor Disease Control and Prevention, 2020). BRFSS is a series of annual health-related telephone surveysthat collect state-by-state data among U.S. residents regarding their health-related risk behaviors, chronichealth conditions, and use of preventive services. Similar to the NHANES survey methodology, BRFSS dataare weighted to generate estimates representative of the U.S. population. The survey asks about severalhealth conditions in the following way: “Has a doctor, nurse, or other health professional EVER told you thatyou had any of the following?” The item related kidney disease reads, “[Ever told] you have kidney disease?Do NOT include kidney stones, bladder infection or incontinence.” We present analyses of data from thepast six years, including the most recent data from 2018.
Table 1.1 Percentage of adults in the U.S. in KDGIO CKD risk categories, 2003-2018
(a) Percentage by eGFR and ACR, 2015-2018
eGFR Categories
A1: Normal to mildlyincreased
(ACR <30 mg/g)
A2: Moderatelyincreased
(ACR 30-299 mg/g)
A3: Severelyincreased
(ACR ≥300 mg/g) Total
G1: Normal or high (eGFR ≥90ml/min/1.73m²)
53.5 4.1 0.58 58.3
G2: Mildly decreased (eGFR 60-89 ml/min/1.73m²)
31.5 2.9 0.43 34.8
G3a: Mildly to moderately decreased (eGFR 45-59 ml/min/1.73m²)
3.9 0.84 0.27 5.0
G3b: Moderately to severely decreased (eGFR 30-44 ml/min/1.73m²)
0.88 0.40 0.17 1.5
G4: Severely decreased (eGFR 15-29 ml/min/1.73m²)
0.11 0.09 0.17 0.37
G5: Kidney failure (eGFR <15 ml/min/1.73m²)
0.01 0.01 0.09 0.11
Total 90.0 8.3 1.7 100
(b) Trends in percentage in KDIGO CKD risk categories, 2003-2018
2003-2006 2007-2010 2011-2014 2015-2018
Low risk 85.1 86.6 85.2 85.1
Moderately high risk 10.9 9.5 10.8 10.9
High risk 2.7 2.5 2.6 2.7
Very high risk 1.3 1.4 1.5 1.3
Total 100 100 100 100Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinaryACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
In the last two NHANES surveys, encompassing 2015-2018, 14.9% of adults in the U.S. had low eGFR oralbuminuria or both (Table 1.1). The distribution of participants based on KDIGO risk categories defined byeGFR and urinary albumin to creatinine ratio (ACR) (Kidney Disease: Improving Global Outcomes CKDWorkgroup, 2013) was as follows: 10.9% moderate risk, 2.7% high risk, and 1.3% very high risk. Thesepercentages differ little from those obtained in 2001-2004 (Saran et al., 2019).
Figure 1.1 Prevalence of CKD by stage in the U.S., 2003-2018
All Age <65Years
Age 65+Years
Male Female Non-HispanicWhite
Non-Hispanic AfricanAmerican/Black
Hispanic/Latino
By Stage By Survey Year
In 2015-2018, 4.7% of adults had stage 1, 3.3% stage 2, 6.4% stage 3, 0.4% stage 4, and 0.1% stage 5CKD (Figure 1.1). There were no clear trends in prevalence of CKD across time periods except that stage 1CKD increased by 15% (or 0.6% in absolute terms, from 4.1% in 2003-2006 to 4.7% in 2015-2018), anincrease that was particularly prominent among non-Hispanic whites. Examining trends in CKD prevalenceby age group, as expected, CKD was approximately 4 times more prevalent among older (aged ≥65) thanyounger individuals. The prevalence of stage 3 CKD declined in the older population from 31.4% in 2003-2006 to 25.2% in 2015-2018.
Year
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ge
All, By Stage
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serumcreatinine and urinary ACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio; KDOQI, Kidney Disease OutcomesQuality Initiative.
Figure 1.2 Cumulative eGFR distribution in U.S. adults, 2003-2018
All Age <65Years
Age 65+Years
Male Female Non-HispanicWhite
Non-Hispanic AfricanAmerican/Black
Hispanic/Latino
The median eGFR among adults in the U.S. has shifted slightly to the right (slightly higher) from 2003-2006to 2015-2018, from 93.5 ml/min/1.73m to 94.8 ml/min/1.73m (Figure 1.2). The increase in median eGFRwas particularly prominent among older individuals, from 67.2 ml/min/1.73m to 71.4 ml/min/1.73m .
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All
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serumcreatinine and urinary ACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
Figure 1.3 Urinary albumin-creatinine ratios (ACR) in U.S. adults, 2003-2018
All Age <65Years
Age 65+Years
Male Female Non-HispanicWhite
Non-Hispanic AfricanAmerican/Black
Hispanic/Latino
By ACR By Survey Year
In contrast to the improvement in eGFR, albuminuria was stable or increasing, from 2003-2018 (Figure 1.3).Overall, the percentage with ACR ≥10 mg/g increased from 30.1% in 2003-2006 to 32.3% in 2015-2018,and the percentage with ACR ≥30 mg/g increased from 9.6% to 10.0%. In 2015-2018, the percentage ofnon-Hispanic Black individuals with ACR ≥30 mg/g was higher than the percentage of non-Hispanic Whiteindividuals with ACR ≥30 mg/g (12.4% vs. 9.4%). The percentage of Hispanic or Latino individuals withACR ≥30 mg/g was 10.2%, intermediate between rates among Black and non-Hispanic White individuals.
Year
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All, By ACR
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serumcreatinine and urinary ACR measurements. Single-sample, calibrated estimates of ACR. ACR measured as mg of albumin per g of creatinine.
Figure 1.4 Percentage of U.S. adults with urinary ACR ≥30 mg/g by eGFR category, 2003-2018
All Age <65Years
Age 65+Years
Male Female Non-HispanicWhite
Non-Hispanic AfricanAmerican/Black
Hispanic/Latino
By eGFR By Survey Year
Between the first and last period, the prevalence of ACR ≥30 mg/g increased from 8.2% to 8.6% forindividuals with eGFR >60 ml/min/1.73m , from 21.9% to 22.1% for eGFR 45-59 ml/min/1.73m , from33.9% to 39.4% for eGFR 30-44 ml/min/1.73m , and, most strikingly, from 61.0% to 76.4% for eGFR <30ml/min/1.73m (Figure 1.4). At all levels of eGFR, ACR ≥30 mg/g was more common in Black and Hispanicor Latino individuals than in Whites. For example, for eGFR 30-44 ml/min/1.73m , the percentage of Whiteswith ACR ≥30 mg/g was 30.4% versus 58.2% for Blacks and 79.4% for Hispanics or Latinos.
Year
Perc
enta
ge
All, By eGFR
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serumcreatinine and urinary ACR measurements. Single-sample, calibrated estimates of serum creatinine and ACR; eGFR calculated using the CKD-EPI equation.Abbreviations: ACR, urine albumin/creatinine ratio.
Figure 1.5 Prevalence of CKD in U.S. adults within age, sex, race/ethnicity, & risk factor categories, 2003-2018
All Age Sex Race/ethnicity Diabetes Hypertension Cardiovascular disease BMI
Figure 1.5 shows that the overall prevalence of CKD in US adults was stable from 2003-2006 to 2015-2018.However, the prevalence declined in adults ≥65 years from 45.7% in 2003-2006 to 38.6% in 2015-2018(offset by a small increase among younger individuals). The prevalence of CKD declined among Hispanic orLatino individuals relative to non-Hispanic Whites and Blacks. In the most recent period, prevalence waslower among Hispanics or Latinos at 11.9% (vs. 15.7% among non-Hispanic Whites and 16% among non-Hispanic Blacks). In addition, the prevalence of CKD decreased from 42.3% in 2003-2006 to 36.9% in2015-2018 among adults with diabetes (DM) and from 47.7% to 39.6% among those with cardiovasculardisease (CVD). The prevalence of CKD among those with hypertension decreased slightly but remainedhigh, at nearly one-third of the population.
All
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ge
by Survey Year
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serumcreatinine and urinary ACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio; BMI, body mass index.
Figure 1.6 Distribution of CKD in U.S. adults with diabetes, hypertension, cardiovascular disease, and obesity, 2015-2018
Hypertension Diabetes BMI 30+ Cardiovascular Disease Age <65 Years Age 65+ Years
2003-2006 2007-2010 2011-2014 2015-2018
Figure 1.6 displays the prevalence of key conditions associated with CKD among adults in the U.S. and theoverlap between these conditions and indicators of CKD. In 2015-2018, 13.1% of adults had DM, 28.1%had hypertension, 6.7% had CVD, and 41.5% were obese. The prevalence of low eGFR and albuminuriawas higher in these subgroups than among the overall U.S. adult population. Specifically, 17.3% of thosewith DM, 16.6% of those with hypertension, 7.8% of those with BMI ≥30 kg/m², and 25.2% of those withself-reported CVD had eGFR <60 ml/min/1.73m compared with 6.9% in the general population. Theprevalence of ACR ≥30 mg/g was 27.5% among those with DM, 20.8% among adults with hypertension,12.0% among those with BMI ≥30 kg/m², and 23.6% among those with CVD vs. 10% for the general adultpopulation.
Considering overlap in the other direction, adults with indicators of CKD were especially likely to havehypertension, with 67.3% of those with eGFR <60 ml/min/1.73m and 58.3% of those with ACR ≥30 mg/galso having hypertension. Almost one third of those with eGFR <60 ml/min/1.73m and 35.7% of those withACR ≥30 mg/g had DM.
The prevalence of risk factors for CKD, including older age (15.6% to 18.5%), DM (8.5% to 13.1%), andhypertension (24.6% to 28.1%) increased from 2003-2006 to 2015-2018. Thus, reductions in CKD in thesegroups were offset by increases in the numbers of adults with these conditions.
Hypertension
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participantsage ≥20 with serum creatinine and urinary ACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio;BMI, body mass index
Table 1.2 Prevalence of CKD in subgroups of U.S. adults defined by insurance, income, and education level, 2003-2018
All Age 65+ Years
2003-2006 2007-2010 2011-2014 2015-2018
Overall 14.9 13.4 14.8 14.9
Health insurance
Not insured 9.9 7.7 10.8 11.1
Insured 16.8 14.8 15.7 15.5
Health insurance type
Private 13.7 12.3 13.0 13.3
Medicare 43.5 39.8 37.5 36.0
Medicare and private 46.9 40.1 36.9 38.0
Medicaid 25.0 19.5 20.9 16.8
Military 25.2 20.2 17.6 23.9
Family income/poverty ratio
≤1 15.2 14.5 17.5 17.4
>1 14.5 13.1 14.2 14.4
Schooling
Not a High School graduate 21.8 18.6 21.2 19.5
High School graduate/GED 15.6 15.2 15.8 17.2
At least some College 12.5 10.9 12.9 13.1Data source: National Health and Nutrition Examination Survey (NHANES), 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinary ACR. eGFRcalculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
Table 1.2 shows that the prevalence of CKD declined from 2003-2006 to 2015-2018 among Medicarebeneficiaries, consistent with the decline noted in individuals over age 65 (Figure 1.5). However, theprevalence of CKD also declined among those with Medicaid insurance, from 25.0% in 2003-2006 to 16.8%in 2015-2018, possibly related to the expansion of this population in recent years, in which newly coveredindividuals may be a somewhat healthier group. Those without insurance were the only group in which CKDprevalence increased from 2003-2006 (9.9%) to 2015-2018 (11.1%).
In 2015-2018, the prevalence of CKD was more than twice as high among individuals with Medicarecoverage with or without supplemental insurance (36% and 38%, respectively) as among those withMedicaid, private insurance, or no insurance (16.8%, 13.3%, and 15.5%, respectively), which is likelyrelated to the older age of Medicare beneficiaries. Individuals with military coverage had intermediateprevalence at 23.9%. The prevalence of CKD was also higher among individuals with lower income (17.4%among those below the poverty line vs. 14.4% among those above) and lower education (17.2% amongthose with less than a high school education vs. 13.1% among those with at least some college).
Potassium, <4.7 gram 98.1 98.6 98.6 99.0 97.2 95.8 96.5 96.3Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinaryACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio; CKD.
Table 1.3 shows self-reported sedentarism, smoking, vaping, and dietary energy, sodium, and potassiumintake among adults with and without CKD. Sedentary behavior has declined among individuals with CKDfrom 44.9% in 2007-2010 to 35.2% in 2015-2018, accompanied by a smaller decline among those withoutCKD from 26.1% to 24.5%. Nevertheless, individuals with CKD remained more sedentary than thosewithout CKD in 2015-2018 (35.2% vs. 24.5%). Given that CKD is much more common among olderindividuals, we also examined the group aged >65 years separately. Older individuals with and without CKDwere more sedentary than younger individuals. Those with CKD remained more sedentary than thosewithout in 2015-2018 (42.6% vs. 30%).
Individuals with CKD were less likely to be current smokers than those without CKD in all time periods.Rates of smoking declined more among those without CKD, resulting in a narrowing of this gap over time.In 2015-2018, 11.8% of individuals with CKD and 14.3% of individuals without CKD were current smokers.New in 2015-2018, the NHANES survey asked about vaping, and those with CKD were also somewhat lesslikely to report vaping (4.2%, vs. 6.0% among those without CKD). Older individuals were less likely to be
current smokers and much less likely to report vaping than younger individuals, but those with CKD werestill less likely to report these behaviors: 5.6% smoking vs. 8.1% of those without CKD and 0.6% vaping vs.1.3% of those without CKD.
We examined three aspects of healthy dietary intake: energy intake ≥2000 kcal, sodium <2.3 g, andpotassium <4.7 g per day. Individuals with CKD were less likely to report caloric intake >2,000 kcal/dayduring all time periods. However, the percentage increased from 34.1% in 2003-2006 to 39.8% in 2015-2018 among those with CKD while it decreased slightly during the same period from 54% to 50.3% amongthose without CKD, narrowing the gap. Although the minority of individuals meet dietary recommendationsfor sodium intake, those with CKD were more likely to have sodium <2.3g per day (26.5% in 2015-2018 vs.20% among those without CKD). Finally, few individuals met the recommended potassium intake of ≥4.7g/day, regardless of CKD status. There were no clear trends over time, but individuals with CKD wereslightly but consistently more likely to report potassium intake below recommended levels (97.1% vs. 96.0%for those without CKD in 2015-2018, for example). Lower potassium intake was nearly universal amongindividuals with eGFR <60 ml/min/1.73m (99% in 2015-2018), suggesting that recommendations to limitintake in the setting of reduced kidney function could contribute.
Figure 1.7 Sedentary behavior among adults in the U.S. by CKD status, 2007-2018
Figure 1.7 shows that individuals with CKD are more likely to be sedentary than those without CKD (35.2%vs. 24.5% in 2015-2018). However, this difference decreased over the time periods, driven mostly by adecrease from 44.9% to 35.2% in individuals with CKD. Given that the CKD population is older than thepopulation without CKD, we examined the subgroup over age 65. Those with CKD were still less active thanthose without CKD at all time points. The percentage of older individuals who reported being sedentarydeclined to a similar extent over time for those with and without CKD.
2
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Data source: National Health and Nutrition Examination Survey (NHANES), 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinineand urinary ACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
≥100 mg/dL 56.4 59.5 51.7 52.0 59.1 59.4 54.5 64.2Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinaryACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
Table 1.4 shows that most individuals with CKD had a prior diagnosis of hypertension. The minority of thesewere receiving treatment and had blood pressure <130/80. However, treatment and control of bloodpressure among those with CKD and hypertension improved from 31.1% in 2003-2006 to 37.5% in 2015-2018. Blood pressure treatment and control were better among individuals without CKD during all periods.There was improvement from 42.7% in the earliest period to 51% in 2011-2014 with a subsequent declineto 44.5% in 2005-2018. A similar percentage of individuals with and without CKD (16.4% and 18.7%) hadblood pressure ≥130/80 despite not having a prior diagnosis of hypertension. Glycemic control worsenedsomewhat over time among adults with CKD while improving over the same period among those withoutCKD. In 2015-2018, 69% of those with CKD and 79.3% of those without CKD had A1c <8%. Thepercentage of individuals with CKD whose fasting LDL levels were <70 mg/dL was stable and low atapproximately 11%.
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinaryACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
Figure 1.8 shows the percentage of adults with and without indicators of kidney disease who had bloodpressure ≥140/90 mm Hg or ≥130/80 mm Hg over time. Uncontrolled hypertension was more commonamong individuals with CKD than those without CKD during all time periods. Although blood pressurecontrol did not improve among adults without CKD, the percentage of adults with CKD whose bloodpressure was <130/80 mm Hg improved over time, from 41.3% in 2003-2006 to 45.7% in 2015-2018. Thisimprovement was more prominent among those with eGFR <60 ml/min/1.73m (from 36.3% to 48.8% withcontrolled blood pressure).
Nevertheless, less than half of individuals with CKD had controlled blood pressure in 2015-2018, using thecurrent target of <130/80 mm Hg (Whelton et al., 2018). In addition, more than one third of individuals withCKD had blood pressure >140/90 mm Hg in 2015-2018, and, perhaps more concerningly, approximatelyone-third of U.S. adults without CKD had blood pressure above 130/80 mm Hg in the most recent period.
Figure 1.9 Percentage of adults in the U.S. with cholesterol levels above the target range, by CKD status, 2003-2018
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinaryACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio; LDL, low density lipoprotein.
A large percentage of adults with and without CKD had LDL cholesterol levels ≥70 mg/dL (89.4% and91.4%, respectively, in 2015-2018), and these percentages changed little over time (Figure 1.9). Amongindividuals with eGFR <60 ml/min/1.73m , 87.2% had LDL cholesterol ≥70 mg/dL. Current guidelinessuggest that eGFR <60 ml/min/1.73m (with or without albuminuria) is a risk-enhancing factor (Grundy etal., 2019), and treatment to LDL below 70 mg/dL would be recommended for many of these individualsbetween 40 and 75 years of age.
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serum creatinine and urinaryACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
Although a hemoglobin A1c target of <7% is appropriate for many individuals with DM, less stringent A1cgoals (such as <8%) may be appropriate for some individuals (American Diabetes Association, 2019).Therefore, we present A1c levels in three categories: <7%, 7 to <8%, and ≥8%, with levels ≥8% consideredto be poor glycemic control. Figure 1.10 shows that poor glycemic control (A1c ≥8%) was similar amongindividuals with and without CKD in 2003-2006 at 26.4% and 26.8%. However, glycemic control worsenedamong individuals with CKD more than among those without CKD through 2011-2014 before improving inthe most recent period: in 2015-2018, 31.0% of individuals with CKD and 20.7% of those without CKD hadpoorly controlled glycemia. It will be important to monitor whether the recent improvement continues infuture years.
Figure 1.11 Percentage of U.S. adults with CKD aware of their kidney disease, 2003-2018
CKD stage By eGFR and ACR By Diabetes and Hypertension
Figure 1.11 shows that although awareness among individuals with CKD has increased over time, the vastmajority of individuals with kidney disease remain unaware. Only 7.2% were aware of their kidney diseasein 2003-2006, and by 2015-2018, the percentage who were aware increased only to 12.1%. For all timeperiods, awareness of kidney disease was higher among those with DM, hypertension, or both (10.4%,13.8%, and 20.0%, respectively in 2018) than among those without these conditions (4.5% in 2018). Thosewith more advanced stages of kidney disease were also more likely to be aware than those with earlierstages, although recognition was still low even in stage 3 (16.9%, compared with 61.9% for stage 4 and86.3% for stage 5 in 2018).
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CKD stage
Data source: National Health and Nutrition Examination Survey (NHANES), 2003-2006, 2007-2010, 2011-2014 and 2015-2018 participants age ≥20 with serumcreatinine and urinary ACR. eGFR calculated using the CKD-EPI equation. Abbreviations: ACR, urine albumin/creatinine ratio.
Figure 1.12 Estimated prevalence of self-reported kidney disease by state among Behavioral Risk Factors Surveillance Systemparticipants aged 18 and older
Data source: Behavioral Risk Factor Surveillance System (BRFSS), 2013, 2014, 2015, 2016, 2017 and 2018 participants age ≥18.
According to responses on the BRFSS, the prevalence of self-reported kidney disease in the U.S. as awhole has increased from 2.6% in 2013 to 3.1% in 2018. The lower rates of self-reported kidney disease,compared with the rates observed in NHANES based on eGFR and albuminuria, suggest that fewer than 1in 5 individuals with kidney disease is aware of his or her condition. Furthermore, it is not possible toascertain whether differences in rates over time are related to increased disease prevalence or increasedrecognition (which is why we have used NHANES data to address the question of CKD prevalence overtime).
The strength of the BRFSS survey is that it collects state-level data. Figure 1.12 shows the prevalence ofself-reported kidney disease by state. Across states, the range of self-reported kidney disease prevalencein 2018 ranged from 2.0% to 4.6%. Prevalence was above 4% in West Virginia, Kentucky, and Guam in2018, whereas Montana, Vermont, and Colorado had rates <2.2%.
SummaryThe overall prevalence of CKD in the U.S. adult population surveyed in 2015-2018 was 14.9% (based on asingle examination demonstrating low eGFR or albuminuria). Although this percentage is nearly identical tothe prevalence of CKD in the 2003-2006 years of the NHANES, it may mask some improvement. First, theU.S. population has aged over this time period, so that a stable rate represents progress. This phenomenoncan be appreciated by examining age-stratified results. The prevalence of CKD among individuals underage 65 changed little from 8.7% to 9.0% (Figure 1.5), whereas there was a large decline from 45.7% to38.6% among older individuals. The reduction in CKD was driven by fewer people with low eGFR ratherthan a reduction in the prevalence of albuminuria. Indeed, the median eGFR increased among those overand under age 65, albeit to a greater extent among those over age 65 (Figure 1.2). The increase in eGFRamong older individuals translated into a reduction in the prevalence of stage 3 and 4 CKD among thoseover age 65. Thus, it appears that eGFR decline among older individuals has slowed over time, but thepercentage of individuals over age 65 who are at higher risk of CKD has increased simultaneously. The netresult is a stable overall prevalence of CKD in the setting of clear improvement among older individuals.
Second, the prevalence of CKD declined within key risk groups, including those with diabetes andhypertension, suggesting that medical management of these conditions may have improved over theinterval. Given the large proportion of CKD attributable to these conditions, one would have expected that areduction in the prevalence of CKD among individuals with these conditions would have resulted in adecline in the overall prevalence of CKD. Unfortunately, however, the prevalence of hypertension anddiabetes increased over the same time period. These observations have important public healthimplications. Although there appears to have been some progress in prevention of CKD among individualswith diabetes and hypertension, the prevalence remains over 30% for both groups, suggesting there isroom for further improvement. Suboptimal control of these risk factors can be seen by examining bloodpressure and A1c measures: one third of individuals without CKD had blood pressure above target levels,and nearly half had A1c values ≥7%.
Increasing rates of obesity, hypertension, and diabetes offset (or effectively “negated”) all progressachieved through lower rates of CKD within these groups, highlighting the importance of addressing thesemajor risk factors in efforts to reduce the overall burden of CKD. The need for prevention of risk factors“upstream” of CKD can be appreciated by considering lifestyle factors. Approximately one quarter ofindividuals without CKD were sedentary, and there has been little reduction in sedentary behavior in thispopulation over time. Adherence to a low sodium diet was worse, with 80% not meeting recommendedtargets. These modifiable factors may be contributing to the increase in obesity and hypertension and,ultimately, CKD. The public health risk of sedentary behavior and poor diet are widely appreciated, but therehas been less emphasis on their role in the development of CKD than on their impact on cardiovasculardisease.
Data in this chapter raise concerns that more could be done to slow progression of established CKD aswell. For example, over half of individuals with CKD had blood pressure above recommended targets, andover two thirds had high sodium intake in the most recent period, a situation that has been worsening over
time. However, the cross-sectional nature of NHANES data do not allow for assessment of progression ofCKD. We will examine this issue further using Medicare data in Chapter 2.
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