Racial Disparities in Creatinine-based Kidney Function Estimates Among HIV-infected Adults

Incidence of non-AIDS defining comorbidities among young adults with perinatally acquired HIV in North America

OBJECTIVE

The aim of this study is to describe the incidence of diabetes mellitus type 2 (T2DM), hypercholesterolemia, hypertriglyceridemia, hypertension, and chronic kidney disease (CKD) from 2000 to 2019 among North American adults with perinatally acquired HIV (PHIV) aged 18-30 years.

DESIGN

Description of outcomes based on electronic health records for a cohort of 375 young adults with PHIV enrolled in routine HIV care at clinics contributing data to the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD).

METHODS

We estimated overall, sex, and race-stratified cumulative incidences using Turnbull estimation, and incidence rates using quasi-Poisson regression. T2DM was defined as glycosylated hemoglobin more than 6.5% or based on clinical diagnosis and medication use. Hypercholesterolemia was based on medication use or total cholesterol at least 200 mg/dl. Hypertriglyceridemia was based on medication use or fasting triglyceride at least 150 mg/dl or nonfasting at least 200 mg/dl. Hypertension was based on clinical diagnosis. CKD was defined as estimated glomerular filtration rates less than 90 ml/mi|1.73 m 2 for at least 3 months.

RESULTS

Cumulative incidence by age 30 and incidence rates from age 18 to 30 (per 100 person-years) were T2DM: 19%, 2.9; hypercholesterolemia: 40%, 4.6; hypertriglyceridemia: 50%, 5.6; hypertension: 22%, 2.0; and CKD: 25%, 3.3. Non-Black women had the highest incidence of hypercholesterolemia and hypertriglyceridemia, Black adults had the highest hypertension incidence, and Black men had the highest CKD incidence.

CONCLUSION

There was a high incidence of five chronic comorbidities among people with PHIV. Earlier screening at younger ages might be considered for this unique population to strengthen prevention strategies and initiate treatment in a timely way.

Removal of ethnicity adjustment for creatinine-based estimated glomerular filtration rate equations

Creatinine-based estimated glomerular filtration rate equations (eGFRcreatinine) are used to measure excretory kidney function in clinical practice. Despite inter and intra-patient variability, eGFRcreatinine has excellent clinical utility and provides the basis for the classification system for chronic kidney disease (CKD), for kidney function monitoring, treatment interventions and referral pathways. The 4-variable modification of diet in renal disease (MDRD) eGFRcreatinine equation was introduced in 2000 and recommended by the National Institute for Health and Care Excellence (NICE) in 2008. Subsequently, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) eGFRcreatinine equation was introduced in 2009 and is more accurate than MDRD in patients with mild and moderate CKD. In 2014, NICE recommended that CKD-EPI eGFRcreatinine replace MDRD eGFRcreatinine in routine clinical practice across England. Both equations originally incorporated adjustments for age, gender and ethnicity. However, the evidence for ethnicity adjustment has been increasingly questioned, and in 2021 NICE recommended that kidney function should be estimated by CKD-EPI eGFRcreatinine without using ethnicity adjustment. Recently, a CKD-EPI equation has been presented without ethnicity adjustment; however, this has not been validated outside of North America and NICE continues to recommend CKD-EPI 2009. We review the status of eGFRcreatinine in clinical practice, including the limitations of eGFRcreatinine and the rationale for removal of ethnicity adjustment and the potential impact of this change on clinical care for patients with kidney disease.

Limited Evidence for Use of a Black Race Modifier in eGFR Calculations: A Systematic Review

Background

Commonly used estimated glomerular filtration rate (eGFR) equations include a Black race modifier (BRM) that was incorporated during equation derivation. Race is a social construct, and a poorly characterized variable that is applied inconsistently in clinical settings. The BRM results in higher eGFR for any creatinine concentration, implying fundamental differences in creatinine production or excretion in Black individuals compared to other populations. Equations without inclusion of the BRM have the potential to detect kidney disease earlier in patients at the greatest risk of chronic kidney disease (CKD), but also has the potential to over-diagnose CKD or impact downstream clinical interventions. The purpose of this study was to use an evidence- based approach to systematically evaluate the literature relevant to the performance of the eGFR equations with and without the BRM and to examine the clinical impact of the use or removal.

Content

PubMed and Embase databases were searched for studies comparing measured GFR to eGFR in racially diverse adult populations using the Modification of Diet in Renal Disease or the 2009-Chronic Kidney Disease Epidemiology Collaboration-creatinine equations based on standardized creatinine measurements. Additionally, we searched for studies comparing clinical use of eGFR calculated with and without the BRM. 8,632 unique publications were identified; an additional 3 studies were added post-hoc. In total, 96 studies were subjected to further analysis and 44 studies were used to make a final assessment.

Summary

There is limited published evidence to support the use of a BRM in eGFR equations.

Estimated glomerular filtration rate equations in people of self-reported black ethnicity in the United Kingdom: Inappropriate adjustment for ethnicity may lead to reduced access to care

Assessment in African populations suggest adjustment for ethnicity in estimated glomerular filtration rate (eGFR) equations derived from African Americans lead to overestimation of GFR and failure to determine severity in chronic kidney disease (CKD). However, studies in African Europeans are limited. We aimed to assess accuracy of eGFR equations, with and without ethnicity adjustment compared with measured GFR in people of Black ethnicity in the United Kingdom. Performance of MDRD, CKD-EPI (with and without ethnicity adjustment), Full Age Spectrum (FAS), revised Lund Malmö (LM Revised), and European Kidney Function Consortium (EKFC) eGFR equations were assessed compared to 51Cr-EDTA GFR studies extracted from hospital databases. Participants with albumin <30g/l, liver disease, <18 years, of non-Black or non-White self-reported ethnicity were excluded. Agreement was assessed by bias, precision and 30%-accuracy and was stratified for ethnicity and GFR. 1888 51Cr-EDTA studies were included (Mean age-53.7yrs; 43.6% female; 14.1% Black ethnicity). Compared to White participants, eGFR-MDRD and eGFR-CKD-EPI equations in Black participants significantly overestimated GFR (bias 20.3 and 19.7 ml/min/1.73m2 respectively, p<0.001). Disregarding the ethnicity adjustment significantly improved GFR estimates for Black participants (bias 6.7 and 2.4ml/min/1.73m2 for eGFR-MDRD and eGFR-CKD-EPI respectively, p<0.001). The LM Revised equation had the smallest bias for both White and Black participants (5.8ml and -1.1ml/min/1.73m2 respectively). 30%-accuracy was superior for GFR≥60ml/min/1.73m2 compared to <60ml/min/1.73m2 using eGFR-CKD-EPI equation for both White and Black participants (p<0.001). Multivariate regression methodology with adjustment for age, sex and log(serum creatinine) in the cohort yielded an ethnicity coefficient of 1.018 (95% CI: 1.009-1.027). Overestimation of measured GFR with eGFR equations using ethnicity adjustment factors may lead to reduced CKD diagnosis and under-recognition of severity in people of Black ethnicity. Our findings suggest that ethnicity adjustment for GFR estimation in non-African Americans may not be appropriate for use in people of Black ethnicity in the UK.

Current Management Strategies of Chronic Kidney Disease in Resource-Limited Countries

The incidence and prevalence of chronic kidney disease (CKD) and kidney failure continues to increase worldwide, especially in resource-limited countries. Many countries in this category already have a massive burden of communicable diseases, as well as socio-economic and socio-demographic challenges. The rising CKD burden and exorbitant economic cost associated with treatment are mainly responsible for the alarming mortality rate associated with kidney disease in these regions. There is often poor risk factor (diabetes and hypertension) and CKD awareness in these countries and limited availability and affordability of treatment options. Given these observations, early disease detection and preventive measures remain the best options for disease management in resource-limited settings. Primary, secondary and tertiary preventive strategies need to be enhanced and should particularly include measures to increase awareness, regular assessment to detect hypertension, diabetes and albuminuria, options for early referral of identified patients to a nephrologist and options for conservative kidney management where kidney replacement therapies may not be available or indicated. Much is still needed to be done by governments in these regions, especially regarding healthcare funding, improving the primary healthcare systems and enhancing non-communicable disease detection and treatment programs as these will have effects on kidney care in these regions.

Association of Genetic Polymorphisms of TGF-β1, HMOX1, and APOL1 With CKD in Nigerian Patients With and Without HIV

RATIONALE & OBJECTIVE

Recent studies in the human immunodeficiency virus (HIV)-infected population have suggested that there are genetic predispositions to the development of chronic kidney disease (CKD) in this context. We investigated the association of genetic polymorphisms of the genes encoding apolipoprotein L1 (APOL1), transforming growth factor β1 (TGF-β1; a profibrotic cytokine), and heme oxygenase 1 (HMOX1) with prevalent CKD among adults with and without HIV infection.

STUDY DESIGN

Case-control study.

SETTING & PARTICIPANTS

West African adults including 217 HIV-infected patients with CKD (HIV⁺/CKD⁺ group), 595 HIV-infected patients without CKD (HIV⁺/CKD^- group), 269 with CKD and no HIV infection (HIV^-/CKD⁺ group), and 114 with neither CKD nor HIV (HIV^-/CKD^- group).

EXPOSURE

The genetic polymorphisms with reference single-nucleotide polymorphism (rs) identification numbers rs1800469 (TGF-β1), rs1800470 (TGF-β1), rs121918282 (TGF-β1); rs60910145 (APOL1 G1 risk allele), rs73885319 (APOL1 G1 risk allele), rs71785313 (APOL1 G2 risk allele), and rs743811 (HMOX1); HIV.

OUTCOME

CKD.

ANALYTICAL APPROACH

Single-nucleotide polymorphism (SNP) genotyping of rs1800469 (TGF-β1), rs1800470 (TGF-β1), rs121918282 (TGF-β1); rs60910145 (APOL1), rs73885319 (APOL1), rs71785313 (APOL1), and rs743811 (HMOX1) was performed. Hardy-Weinberg equilibrium was evaluated for all SNPs, and minor allele frequencies were reported. A case-control analysis was performed, and multivariable logistic regression was used to control for potential confounders.

RESULTS

Minor allele frequencies for TGF-β1 (rs1800469, rs1800470, and rs1800471), APOL1 (rs60910145, rs73885319, and rs71785313), and HMOX1 (rs743811) were 0.25, 0.46, 0.46, 0.44, 0.45, 0.17, and 0.14, respectively. Among HIV-positive individuals, only TGF-β1 rs1800470 (GG vs AA), APOL1 (in the recessive model), and hypertension were associated with prevalent CKD (adjusted ORs of 0.44 [95% CI, 0.20-0.97], 2.54 [95% CI, 1.44-4.51], and 2.17 [95% CI, 1.35-3.48], respectively). No SNP polymorphisms were associated with prevalent CKD among HIV-negative individuals.

LIMITATIONS

The lack of histopathology data for proper categorization of the type of HIV-related nephropathy.

CONCLUSIONS

APOL1 polymorphisms were highly prevalent in this population and among adult patients infected with HIV and were associated with increased CKD risk. The TGF-β1 (rs1800470) polymorphism was associated with reduced risk, and HMOX1 polymorphisms were unassociated with CKD.

Measured (and estimated) glomerular filtration rate: reference values in West Africa

Background

Establishment of normal reference values for glomerular filtration rate (GFR) is mandatory in nephrology. However, no data are available for measured GFR (mGFR) in Africa.

Methods

GFR was measured in 237 healthy adult subjects (103 women and 134 men, mean age 34 ± 10 years) by iohexol plasma clearance.

Results

The mean mGFR was 103 ± 17 mL/min/1.73 m2 and the median value was 103 mL/min/1.73 m2 (2.5th and 97.5th percentiles are 76 and 137 mL/min/1.73 m2, respectively). No significant difference in mGFR results was observed in patients < 40 years of age, whereas a significant decline in mGFR was observed after 40 years of age. There was no significant difference between mGFR in men and women.

Conclusions

Normal GFR values and descriptions of percentiles are now available for West Africa. As in Caucasians, no significant difference was observed between men and women. Moreover, the same age-associated decline in mGFR is also observed after 40 years of age, as in Caucasians.

Prevalence and correlates of chronic kidney disease (CKD) among ART-naive HIV patients in the Niger-Delta region of Nigeria

Widespread use of antiretroviral therapy (ART) in human immunodeficiency virus (HIV) patients has led to improved longevity with the attendant increase in noncommunicable disease prevalence including chronic kidney disease (CKD). This study documents the prevalence of CKD in a large HIV population in Southern Nigeria.This is a single center, 15-year analysis in ART-naïve patients. CKD was defined as the occurrence of estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m on 2 consecutive occasions 3 to 12 months apart using the chronic kidney disease epidemiology collaboration (CKD-EPI) equation. The Cochran-Armitage and Cuzick tests were employed to assess for trend across the years for CKD prevalence and CD4 count, respectively. Multivariable logistic regression models were used to identify independent associations with CKD.In all, 1317 patients (62.2% females) with mean age of 34.5 years and median CD4 count of 194 cells/μL were included. CKD prevalence was 13.4% (95%CI 11.6%-15.4%) using the CKD-EPI equation (without the race factor). Multivariable analysis identified increasing age and CD4 count <200 cells/μL as being independently associated with CKD occurrence.This study reports a high prevalence of CKD in ART-naïve HIV-infected patients. Measures to improve diagnosis of kidney disease and ensure early initiation of treatment should be integrated in HIV treatment programmes in this setting.

The global burden of chronic kidney disease: estimates, variability and pitfalls

Chronic kidney disease (CKD) is currently defined by abnormalities of kidney structure or function assessed using a matrix of variables - including glomerular filtration rate (GFR), thresholds of albuminuria and duration of injury - and is considered by many to be a common disorder globally. However, estimates of CKD prevalence vary widely, both within and between countries. The reasons for these variations are manifold, and include true regional differences in CKD prevalence, vagaries of using estimated GFR (eGFR) for identifying CKD, issues relating to the use of set GFR thresholds to define CKD in elderly populations, and concerns regarding the use of one-off testing for assessment of eGFR or albuminuria to define the prevalence of CKD in large-scale epidemiological studies. Although CKD is common, the suggestion that its prevalence is increasing in many countries might not be correct. Here, we discuss the possible origins of differences in estimates of CKD prevalence, and present possible solutions for tackling the factors responsible for the reported variations in GFR measurements. The strategies we discuss include approaches to improve testing methodologies for more accurate assessment of GFR, to improve awareness of factors that can alter GFR readouts, and to more accurately stage CKD in certain populations, including the elderly.