Disparities in Identification of CKD

Population-based screening and identification strategies for patients with CKD remain a challenge. Data from the Behavioral Risk Factors Surveillance System suggest that most patients with CKD do not know they have the condition. Screening strategies such as albuminuria and serum creatinine determinations are not widely used in the general population and are performed only on indication; hence, most patients with CKD go undetected, for several reasons.

First, although screening is indicated in patients with traditional risk factors for CKD, including diabetes, hypertension, older age, cardiovascular disease, history of acute kidney injury, and a family history of CKD, screening is generally not recommended in patients without risk factors (1). In comparison with whites (7.1%), the adjusted prevalence of diabetes is 12.6% in African Americans, 16.1% in Native Americans and Alaskan Natives, and 11.8% in Hispanics (2); therefore, minority populations should be targeted for CKD screening.

The prevalence of hypertension among non-Hispanic blacks (41.2%) is higher than that for non-Hispanic whites (28.0%) and Hispanic adults (25.9%); therefore, blacks/African Americans with a history of hypertension should specifically be targeted for CKD screening (3). Furthermore, hypertension awareness (85.7% vs. 82.7%) and treatment rates (77.4% vs. 76.7%) are higher, but hypertension control (49.5% vs. 53.9%) is lower in non-Hispanic blacks than in non-Hispanic whites, suggesting a higher risk for CKD in non-Hispanic blacks (4). Interestingly, these lower rates of blood pressure control are highly prevalent in non-Hispanic blacks, even with higher overall use of blood pressure–lowering medications, further highlighting the need to focus on increasing identification of CKD in particular racial and ethnic groups.

A second consideration regarding disparities in identification of CKD is that compared with individuals of European descent, African Americans have a threefold to fivefold greater risk of CKD, attributed in part to two African ancestral genetic variants (termed G1 and G2) of the APOL1 gene on chromosome 22. Those with two risk alleles have been shown to have a sevenfold to 30-fold increased risk for the development of hypertension-related CKD and faster progression of CKD (5). It is estimated that approximately 36% of African Americans carry at least one APOL1 G1 or G2 risk allele, and 14% carry two APOL1 risk alleles (6). By contrast, G1 and G2 alleles are absent in people of European ancestry. The high allele frequency in the African American population has been attributed to evolutionary selection for their protective effect against infection by the parasitic trypanosome Trypanosoma brucei rhodesiense, which causes the most deadly form of African sleeping sickness. Despite this knowledge, no routine clinical testing is yet available for these gene variants as part of risk stratification for CKD in African American patients with hypertension.

Third, CKD is not part of any incentive-based payment model for primary care physicians (PCPs), and despite the benefits of early referral from primary care to nephrologists (79), PCPs recognize and recommend specialist care for progressive CKD less frequently than might be expected. The barriers identified for this discrepancy include lack of awareness of clinical practice guidelines and lack of clinical and administrative resources (10, 11).

There is an opportunity to define ways by which PCPs, through incentive-based payments, can have the needed administrative and clinical resources to enhance early referral of patients with CKD. Midlevel providers such as advanced practice nurses can enhance the ability of PCPs to be more efficient at detecting and referring patients early in their CKD trajectory (12). More of such midlevel resources are needed because even when the referral from a PCP to a nephrologist is optimal, we do not have sufficient numbers of nephrologists to manage the volume of referrals.

In the past decade, the number of internal medicine residents choosing nephrology for subspecialty training has progressively declined (13), worsening the already existing and growing shortage of nephrologists. Thus, there is a call to action for guidelines to better define comanagement strategies between PCPs and nephrologists (14). It is conceivable that such comanagement pathways may allow PCPs to provide evidence-based management to patients with CKD stages 1 to 3 (15), while reserving the treatment of patients with CKD stages 4 to 5 for nephrologists and other subspecialists (e.g., endocrinologists, cardiologists, and nutritionists). Shared decision-making has been explored for patients in advanced CKD stages to facilitate their choices for renal replacement therapy (RRT) and end-of-life care but has not been explored at the time of CKD diagnosis (16). Such an approach may likely promote patient engagement in self-care to participate in kidney health strategies.

Taken together, these three considerations constitute a major access issue in CKD. Patients are not identified early, they are not referred early, and there aren’t sufficient numbers of nephrologists to handle the volume of CKD patients in the population. Consequently, minority populations carry the highest burden of delayed referral for CKD care, for a variety of reasons including those related to socioeconomic issues, communication barriers to patient education, and patient-related issues such as patients’ beliefs, religious practices, and lack of trust in the healthcare system.

Physician bias in treating minority patients

Physician bias in treating minority patients also plays a role (17). Even among patients with health insurance, delayed referral to a nephrologist has been shown to be more likely in blacks, Hispanics, and older patients with CKD than in their white or younger counterparts (18, 19).

More recently, Koraishy et al. (20) showed that in a primary care setting, nephrology referrals were significantly more prevalent among patients with fast progression compared with slow progression. Even though a majority of patients with fast progression in the study were not referred, fast progression and being black were associated with increased odds of nephrology referral, suggesting that awareness of the high risk of CKD in black patients can improve the referral rates in this population. Figure 1 shows a model of early versus late referral in CKD. Early referral provides better patient treatment and better access to all forms of renal replacement therapy (RRT). Late referral results in worse outcomes and in most patients having undergone hemodialysis before they have access to peritoneal dialysis or transplantation as their choice of RRT.

Figure 1.

Model of early versus late referral in CKD

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Early referral provides better patient management and better access to all forms of renal replacement therapy (RRT). Late referral results in worse outcomes and in most patients having to go through hemodialysis (HD, solid lines) before they have access to peritoneal dialysis (PD) or transplantation (dashed lines) as their choice of RRT.

Recent advances in informatics, data science, and molecular biomarkers may be a potential solution to these problems. Electronic medical records have been adopted nearly universally across health systems, and although they have certain limitations, they contain a multitude of longitudinal granular information. This information can be integrated with prognostic biomarkers that have high predictive value in early CKD (21) and genomic information (such as APOL1 genotyping) (22) with the use of advanced data science techniques. Thus, comprehensive, multidimensional assessments of kidney risk in high-risk individuals (especially those with type 2 diabetes and those of African ancestry) can be generated and integrated with both the electronic medical record and care management tools, ensuring that appropriate care guidelines are being followed and tracked. Finally, large-scale analytics can be performed to quantify the population health impact of these measures, especially in vulnerable minority populations.

January 2019 (Vol. 11, Number 1)

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