There are two main findings in this study. First, we found that – contrary to our hypothesis – individual awareness of CKD was not associated with better BP or glycemic control or more use of ACEI/ARB. Second, although we newly demonstrate an increase in attainment of BP control over time, we document overall low prevalences of BP control, ACEI/ARB use and glycemic control in the US adult population with CKD using recent NHANES data. This adds to prior literature documenting limited achievement of guideline-concordant care among study populations [7
Individual awareness of chronic diseases, such as diabetes, hypertension, and congestive heart failure, has been associated with greater individual engagement in health care and adherence to medical therapies [18
]. Educational interventions among patients nearing renal replacement therapy have also been associated with improvements in health outcomes, such as delays in initiation of dialysis and increased overall survival [23
]. Thus, there is strong reason to believe that individual awareness of CKD would be associated with improved intermediate outcomes, such as achievement of guideline-concordant CKD care. Our findings that participant awareness of CKD was not associated with greater achievement of any of the three outcomes examined, were unexpected.
These findings, consistent with data from the Kidney Early Evaluation Program (KEEP) that have also demonstrated lack of association between CKD awareness and odds of BP control [7
], may be explained in a variety of ways. Of course, it is possible that individual awareness of CKD does not actually influence achievement of guideline-concordant CKD care, contrary to what has been seen in other diseases. However, our data may also result from factors that obscure the true association between awareness and attainment of guideline-concordant care. Perhaps provider recognition of CKD and subsequent prescription of appropriate evidence-based CKD therapies play a far greater role than individual awareness of CKD in assuring good BP control, ACEI/ARB use and glycemic control. If individual awareness of CKD is not associated with provider prescription of CKD therapies, its influence on the outcomes studied would be minimal, consistent with our results. This could occur if health care providers are not fully aware of the CKD guidelines, do not believe the evidence behind the recommendation of such therapies, or believe that the prescription of such therapies is futile. It is also conceivable that providers become aware of, or focus on, their patients’ CKD only at very advanced stages, at which point achievement of good BP and glycemic control and ACEI/ARB therapy may be limited by side effects related to low eGFRs.
Additionally, our results may be due to poor discrimination among individuals who are aware vs. unaware of their CKD. Ascertainment of CKD awareness in the NHANES survey is through the following question: ‘Have you ever been told by a doctor or other health professional that you have weak or failing kidneys (excluding kidney stones, bladder infections, or incontinence)?’ While this question may be very specific for CKD awareness – only 1.5% of individuals without CKD responded ‘yes’ to being aware of having CKD – it may lack sensitivity. Inclusion of individuals in the ‘unaware’ group, rather than the ‘aware’ group would result in misclassification and bias our study results towards the null.
The NHANES question is the only metric currently used to estimate population trends in CKD awareness. Our results raise concern that the question may have poor performance characteristics, i.e., it may be very insensitive, particularly among individuals with limited health literacy, who have lower objective knowledge about kidney disease [25
]. To the best of our knowledge, the question used in NHANES has not been validated against a gold standard. Further, it lacks face validity. In an informal survey of practicing nephrologists, none volunteered that they use the terms ‘weak or failing’ kidneys to describe chronic kidney disease, except when patients are very close to needing dialysis (i.e. stage 5 CKD). While our study outcomes – achievement of guideline-concordant CKD care – are imperfect benchmarks against which this question should be evaluated, we believe that they offer insight into the limitations of this question.
There are several limitations to this study. Causality cannot be inferred because of the cross-sectional nature of NHANES data. Also, reverse causality (e.g., difficult-to-control BP leading to increased awareness of underlying CKD among providers and patients) cannot be ruled out. Further, the association between individual awareness of CKD and achievement of evidence-based medical therapies may be confounded by severity of CKD, as it is much more difficult to achieve BP control, maintain daily ACEI/ARB use, and achieve glycemic control in individuals with low eGFRs. While we used propensity scores to account for CKD severity, residual confounding may still be present. In addition, provider characteristics and details about provider-patient relationships, which likely affect guideline-concordant care, were not available. Also, we did not have data on persistently low renal function or albuminuria, which may have led to misclassification of CKD status.
In summary, prevalences of guideline-concordant CKD outcomes are low, though prevalence of BP control has recently increased. In addition, individual awareness of CKD does not appear to be associated with outcomes consistent with guideline concordant care. This suggests that CKD awareness may be important, but insufficient for achievement of optimal CKD care. Greater confidence in our metric to measure CKD awareness is necessary prior to fully embracing these results. Nevertheless, our findings challenge us to better understand the implications of CKD awareness in order to develop educational interventions aimed at improving health outcomes among individuals with CKD.