A total of 1314 participants had CKD stage 3 from 1999 to 2004; of these, 7.8% were aware of their CKD . Participants with CKD stage 3 who were non-Hispanic black or Mexican American had higher rates of awareness than participants of non-Hispanic white or other races. A greater proportion of men were aware of their CKD compared with women. Chronic kidney disease awareness was far greater, but still less than one-fifth, among participants who had proteinuria, diabetes, hypertension, and obesity compared with those who did not. Those with less education and those with a routine site for health care were also more likely to be aware of their CKD, but these associations were not statistically significant. Within individual survey years, the associations of awareness with patient characteristics were generally similar to those seen in the overall study period , although statistical significance was often lost in these small subgroups. For example, male sex was associated with increased awareness for all years, but the association was only statistically significant for 1999-2000. The association of CKD awareness with proteinuria in these stage 3 participants was statistically significant for all 3 survey year periods, with macroalbuminuria being far more predictive than microalbuminuria. Diabetes and hypertension were statistically significantly associated with CKD awareness in 2001-2002 and 2003-2004 only.
In adjusted models, male sex, proteinuria, diabetes, and hypertension were all statistically significantly associated with greater odds of CKD awareness . Older age was associated with less awareness overall, and black race was associated with more awareness; however, the associations were not statistically significant. The increase in awareness over time can be seen in both the younger and older and white and black subgroups. Similarly, awareness increased in men and women from 1999 to 2002, but men remained more likely to be aware in all 3 survey year periods . Regardless of proteinuria subgroup, awareness increased after 1999-2001, with macroalbuminuria being a greater predictor than microalbuminuria in all 3 survey year periods. The same trend was seen for diabetes, with awareness increasing over time and diabetic individuals remaining more likely to be aware. Hypertensive participants were more likely to be aware, especially in the last 2 survey year periods, but it is unclear whether awareness increased in nonhypertensive participants .
After adjustment for other factors, having a routine site for health care (adjusted OR for 1999-2004, 2.56; 95% confidence interval [CI], 0.63-10.3), having a high school education or greater (adjusted OR for 1999-2004, 0.70; 95% CI, 0.35-1.38), being uninsured (adjusted OR for 1999-2004, 0.92; 95% CI, 0.25-3.36), and being obese (adjusted OR for 1999-2004, 1.45; 95% CI, 0.83-2.54) were not associated with CKD awareness.
We found that disease awareness among US adults with CKD, as defined by Kidney Disease Outcomes Quality Initiative staging, was generally low. Even at CKD stage 4, fewer than half of the persons with CKD were aware of their disease. There were increases in CKD awareness after 2000, consistent across subgroups but seen only in those with CKD stage 3, which are arguably impressive for this short period; however, awareness among these persons was still fewer than 1 in 10. Substantial recent efforts to increase awareness among nephrologists (dissemination of Kidney Disease Outcomes Quality Initiative staging in 2002) and general physicians and persons in the general public (formation of the National Kidney Disease Education Program by the National Institutes of Health in 2001 and the initiation of a free screening program by the National Kidney Foundation, the Kidney Early Education Program, piloted in 1997-1999 and continuing today) have not produced high levels of awareness among patients since their implementation several years ago. However, changes in guidelines, coupled with recent increased reporting of eGFR, may be at least partially responsible for differential increase in awareness for CKD stage 3 vs stages 1 and 2. Chronic kidney disease stages 1 and 2 are identified through the presence of proteinuria, which may not be as commonly, or consistently, detected.
Chronic kidney disease awareness rates, at lower than 10% for CKD stage 3 and lower than 50% for CKD stage 4, are still unacceptably low. The discrepancy between CKD awareness and awareness of other chronic diseases is large. Patients with hypertension and diabetes had awareness rates of 74% and 70%, respectively, in the same population during the same period. Both the National High Blood Pressure Education Program of the National Heart, Lung, and Blood Institute, founded in 1972, and the National Diabetes Education Program (through the combined efforts of the National Institutes of Health, Centers for Disease Control and Prevention, and more than 200 private organizations), founded in 1997, ran aggressive public awareness campaigns for many years. Similar long-term, broad-scale efforts in CKD might increase awareness dramatically in the United States, especially if they target both practitioners, who could identify and treat affected individuals, as well as high-risk individuals, who could present to practitioners based on their knowledge of CKD. Given that CKD not only can result in progression to end-stage renal disease and dependence on dialysis and transplantation but also is an independent risk factor for cardiovascular disease and mortality, the importance of increasing CKD awareness should not be underestimated.
Awareness was greater among some subgroups of patients. Black participants with CKD were more likely to be aware of their disease than white participants. This race differential in patient awareness may reflect patient and physician perception of black race as a risk factor for CKD or greater family history among these patients, which may result in more testing among these patients. Increased physician awareness of black race as a risk factor and greater communication of this risk to these patients may also have contributed to the greater CKD awareness seen in black patients. Although older patients are at increased risk for reduced kidney function and CKD, they were less likely to be aware of their disease. Whether this reflects less testing or acceptance of reduced kidney function on the part of the practitioners as a normal part of aging in this population is unknown. Also, although there is no evidence that men are at higher risk of developing CKD than women, men were far more likely to be aware of their CKD. Higher awareness among men may also be due to their higher serum creatinine levels, which physicians, especially those who are less aware of CKD and who use creatinine levels alone rather than age- and sex-adjusted eGFR, may recognize more readily as an abnormality. Physicians may also perceive men to be at higher risk than women and thus screen for CKD more often in these patients; or men’s symptoms of CKD may be more pronounced or less likely to be attributed to other causes than women’s symptoms.
Several clinical conditions made CKD awareness more likely as well. Those with hypertension and diabetes were far more likely to be aware of their disease. This greater likelihood may be because physicians recognize that these patients are at much greater risk for CKD. Patient awareness of their risk may also encourage patients to ask for CKD screening. In addition, these patients are more likely to be seen frequently and thus be subjected to urine and blood testing as part of their regular care, making it more likely for CKD to be detected.
We expected that better access to care might lead to higher rates of disease awareness. However, we found no association between having health insurance and CKD awareness. This suggests that, even when patients have access to care, physician communication of risk and/or patient uptake of the information presented may be inadequate. Having a routine site for health care was marginally associated with greater CKD awareness, after adjustment for other factors. This may be because those at greatest risk, including those with diabetes and hypertension, are more likely to have a routine site for health care because of the condition that puts them at risk for CKD. Given that having a routine site was associated with awareness after adjustment for these conditions, but that merely having health insurance was not, it is also possible that having an established relationship with a health care provider is more important for generating awareness than general access to care. Further efforts to enhance the patient-provider relationship, in the context of discussion of CKD, may improve awareness. Finally, we found that lifestyle factors, such as obesity, physical activity, smoking, and alcohol use, were not associated with CKD awareness.
The urgency of making patients aware of CKD could be questioned on the grounds that many patients die before they progress to a more severe stage of CKD and many are already being treated for diabetes and/or hypertension. However, there are still compelling reasons why patients would benefit from awareness of their CKD. First, they could be made aware of medication exposures that could influence progression, including over-the-counter nonsteroidal anti-inflammatory agents and contrast agents used in imaging tests. In addition, there is evidence that appropriate early treatment (with medications and hypertension control) could slow progression of CKD. Also, patients should be aware that current and future medications could require dose adjustment in the setting of CKD. Many conditions, such as heart disease and cognitive decline, may increase with severity of CKD, and awareness of disease may motivate patients to adopt preventive strategies for these conditions. Awareness might also make patients more vigilant with adherence to dietary recommendations for comorbid hypertension and diabetes, including lower salt, sugar, and fat intake, as well as other lifestyle changes.
There are several limitations to this study that deserve mention. First, the questionnaire item assessing awareness asked participants if they had ever been told they had weak or failing kidneys. Patients may not be told that their kidneys are weak or failing, especially in early-stage CKD; rather, they may be told that they have decreased kidney function or protein in the urine. Thus, there is the possibility of misinterpretation of the questionnaire item by the participants; 1% of respondents without kidney disease answered “yes” to this question, indicating a small amount of misclassification of participant awareness and/or of early-stage disease. Second, proteinuria was a single measurement with no follow-up in NHANES, and CKD in its early stages is defined as persistent proteinuria. This lack of a confirmatory urine protein sample may have led to misclassification of participants with CKD stages 1 and 2. In fact, only 63% of subjects with albuminuria at the first visit in NHANES III had albuminuria at the second visit. Misclassification of disease may have also occurred due to GFR estimation. In addition, we do not know the duration of reduced kidney function and/or proteinuria, nor do we know the duration of symptoms, if any, that may have led the participant to seek medical treatment. The small number of participants with CKD, especially in single surveys, was another limitation. Health care provider factors, especially provider knowledge of CKD, quality of patient-provider communication, and specialist referral, may play a significant role in CKD awareness but could not be assessed using these data.
Despite substantial recent efforts, both nationally and locally, to increase awareness of CKD in the community, the majority of those with CKD, as defined by decreased renal function and/or evidence of kidney damage, do not recall having been told by a physician that they have CKD. Renewed and greater efforts and resources may need to be directed toward dissemination activities by the government (eg, Centers for Disease Control and Prevention and National Kidney Disease Education Program) and private organizations (eg, National Kidney Foundation, American Society of Nephrology, Renal Physicians Association, and American College of Physicians) to increase awareness of CKD among practitioners and in the general community. Not only those with risk factors (eg, diabetes and hypertension) but also those who are less likely to be aware, including older, female, and white patients, without diabetes or hypertension, and those without routine access to health care should be targeted more aggressively. Future studies of disease awareness among those with CKD should focus on intervention by examining patient, health care provider, and societal (eg, public relations campaigns) factors that lead to better CKD awareness.