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Twala NMS, Tade G, Dessein PH, Teckie G. Causes of Chronic Kidney Disease and Their Associations with Cardiovascular Risk and Disease in a Sub-Saharan Low-Income Population. Int J Nephrol Renovasc Dis 2024; 17:175-195. [PMID: 38882658 PMCID: PMC11180468 DOI: 10.2147/ijnrd.s463751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 05/15/2024] [Indexed: 06/18/2024] Open
Abstract
Introduction The causes of chronic kidney disease (CKD) in people living in Sub-Saharan Africa await identification. Also, whether cardiovascular risk and disease extent differ among patients with different CKD etiologies is uncertain. Methods In this prospective cross-sectional study, we examined the presumed causes of chronic kidney disease (CKD) and their relationships with cardiovascular risk and disease in 743 consecutive patients from a sub-Saharan low-income population. Results Hypertensive nephropathy (HNP) (60.2%), diabetic nephropathy (DNP) (24.4%), HIV associated CKD (20.0%) and glomerular disease (13.6%) comprised the major CKD etiologies upon enrolment at the hospital nephrology clinic. Pulse pressure was larger in patients with concurrent HNP and DNP than in those with HNP only (p<0.001). Pulse pressure and systolic blood pressure were larger in HNP or/and DNP patients than those with HIV associated CKD and glomerular disease (p=0.04 to <0.001). Cardiovascular disease was more prevalent in patients with HNP and concurrent HNP and DNP than those from other etiologic categories (p<0.05). HNP and DNP were associated with pulsatile pressures (pulse pressure and systolic blood pressure) independent of one another (p<0.01). In adjusted product of coefficient mediation analysis, mean arterial or distending pressure accounted fully for the potential impact of HNP on pulsatile pressures (103.9-115.7%) but not for that of DNP on the respective pressures (-2.0%-(-)7.5%). Conclusion HNP is by far the most prevalent presumed cause of CKD in this African population. Cardiovascular risk and disease differ markedly across CKD etiological categories.
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Affiliation(s)
- Nkosingiphile Matthew Sandile Twala
- Department of Medicine, Chris Hani Baragwanath Hospital and Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Grace Tade
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Patrick Hector Dessein
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- Internal Medicine Department, Rheumatology division, University of Witwatersrand, Johannesburg, South Africa
| | - Gloria Teckie
- Department of Medicine, Chris Hani Baragwanath Hospital and Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- Division of Nephrology, Department of Medicine, Chris Hani Baragwanath Academic Hospital and Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
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Brandenburg JT, Chen WC, Boua PR, Govender MA, Agongo G, Micklesfield LK, Sorgho H, Tollman S, Asiki G, Mashinya F, Hazelhurst S, Morris AP, Fabian J, Ramsay M. Genetic association and transferability for urinary albumin-creatinine ratio as a marker of kidney disease in four Sub-Saharan African populations and non-continental individuals of African ancestry. Front Genet 2024; 15:1372042. [PMID: 38812969 PMCID: PMC11134365 DOI: 10.3389/fgene.2024.1372042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/12/2024] [Indexed: 05/31/2024] Open
Abstract
Background Genome-wide association studies (GWAS) have predominantly focused on populations of European and Asian ancestry, limiting our understanding of genetic factors influencing kidney disease in Sub-Saharan African (SSA) populations. This study presents the largest GWAS for urinary albumin-to-creatinine ratio (UACR) in SSA individuals, including 8,970 participants living in different African regions and an additional 9,705 non-resident individuals of African ancestry from the UK Biobank and African American cohorts. Methods Urine biomarkers and genotype data were obtained from two SSA cohorts (AWI-Gen and ARK), and two non-resident African-ancestry studies (UK Biobank and CKD-Gen Consortium). Association testing and meta-analyses were conducted, with subsequent fine-mapping, conditional analyses, and replication studies. Polygenic scores (PGS) were assessed for transferability across populations. Results Two genome-wide significant (P < 5 × 10-8) UACR-associated loci were identified, one in the BMP6 region on chromosome 6, in the meta-analysis of resident African individuals, and another in the HBB region on chromosome 11 in the meta-analysis of non-resident SSA individuals, as well as the combined meta-analysis of all studies. Replication of previous significant results confirmed associations in known UACR-associated regions, including THB53, GATM, and ARL15. PGS estimated using previous studies from European ancestry, African ancestry, and multi-ancestry cohorts exhibited limited transferability of PGS across populations, with less than 1% of observed variance explained. Conclusion This study contributes novel insights into the genetic architecture of kidney disease in SSA populations, emphasizing the need for conducting genetic research in diverse cohorts. The identified loci provide a foundation for future investigations into the genetic susceptibility to chronic kidney disease in underrepresented African populations Additionally, there is a need to develop integrated scores using multi-omics data and risk factors specific to the African context to improve the accuracy of predicting disease outcomes.
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Affiliation(s)
- Jean-Tristan Brandenburg
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Strengthening Oncology Services Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Wenlong Carl Chen
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Strengthening Oncology Services Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- National Cancer Registry, National Health Laboratory Service, Johannesburg, South Africa
| | - Palwende Romuald Boua
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Clinical Research Unit of Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | | | - Godfred Agongo
- Navrongo Health Research Centre, Navrongo, Ghana
- Department of Biochemistry and Forensic Sciences, School of Chemical and Biochemical Sciences, C. K. Tedam University of Technology and Applied Sciences, Navrongo, Ghana
| | - Lisa K. Micklesfield
- SAMRC/Wits Developmental Pathways for Health Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Hermann Sorgho
- Clinical Research Unit of Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Stephen Tollman
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gershim Asiki
- African Population and Health Research Center, Nairobi, Kenya
- Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
| | - Felistas Mashinya
- Department of Pathology and Medical Sciences, School of Healthcare Sciences, Faculty of Health Sciences, University of Limpopo, Polokwane, South Africa
| | - Scott Hazelhurst
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa
| | - Andrew P. Morris
- Centre for Genetics and Genomics Versus Arthritis, Centre for Musculoskeletal Research, The University of Manchester, Manchester, United Kingdom
| | - June Fabian
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Wits Donald Gordon Medical Centre, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michèle Ramsay
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Brandenburg JT, Chen WC, Boua PR, Govender MA, Agongo G, Micklesfield LK, Sorgho H, Tollman S, Asiki G, Mashinya F, Hazelhurst S, Morris AP, Fabian J, Ramsay M. Genetic Association and Transferability for Urinary Albumin-Creatinine Ratio as a Marker of Kidney Disease in four Sub-Saharan African Populations and non-continental Individuals of African Ancestry. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.01.17.24301398. [PMID: 38293229 PMCID: PMC10827237 DOI: 10.1101/2024.01.17.24301398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
BACKGROUND Genome-wide association studies (GWAS) have predominantly focused on populations of European and Asian ancestry, limiting our understanding of genetic factors influencing kidney disease in Sub-Saharan African (SSA) populations. This study presents the largest GWAS for urinary albumin-to-creatinine ratio (UACR) in SSA individuals, including 8,970 participants living in different African regions and an additional 9,705 non-resident individuals of African ancestry from the UK Biobank and African American cohorts. METHODS Urine biomarkers and genotype data were obtained from two SSA cohorts (AWI-Gen and ARK), and two non-resident African-ancestry studies (UK Biobank and CKD-Gen Consortium). Association testing and meta-analyses were conducted, with subsequent fine-mapping, conditional analyses, and replication studies. Polygenic scores (PGS) were assessed for transferability across populations. RESULTS Two genome-wide significant (P<5x10-8) UACR-associated loci were identified, one in the BMP6 region on chromosome 6, in the meta-analysis of resident African individuals, and another in the HBB region on chromosome 11 in the meta-analysis of non-resident SSA individuals, as well as the combined meta-analysis of all studies. Replication of previous significant results confirmed associations in known UACR-associated regions, including THB53, GATM, and ARL15. PGS estimated using previous studies from European ancestry, African ancestry, and multi-ancestry cohorts exhibited limited transferability of PGS across populations, with less than 1% of observed variance explained. CONCLUSION This study contributes novel insights into the genetic architecture of kidney disease in SSA populations, emphasizing the need for conducting genetic research in diverse cohorts. The identified loci provide a foundation for future investigations into the genetic susceptibility to chronic kidney disease in underrepresented African populations Additionally, there is a need to develop integrated scores using multi-omics data and risk factors specific to the African context to improve the accuracy of predicting disease outcomes. METHODS Urine biomarkers and genotype data were obtained from two SSA cohorts (AWI-Gen and ARK), and two non-resident African-ancestry studies (UK Biobank and CKD-Gen Consortium). Association testing and meta-analyses were conducted, with subsequent fine-mapping, conditional analyses, and replication studies. Polygenic scores (PGS) were assessed for transferability across populations. RESULTS Two genome-wide significant (P<5x10-8) UACR-associated loci were identified, one in the BMP6 region on chromosome 6, in the meta-analysis of resident African individuals, and another in the HBB region on chromosome 11 in the meta-analysis of non-resident SSA individuals, as well as the combined meta-analysis of all studies. Replication of previous significant results confirmed associations in known UACR-associated regions, including THB53, GATM, and ARL15. PGS estimated using previous studies from European ancestry, African ancestry, and multi-ancestry cohorts exhibited limited transferability of PGS across populations, with less than 1% of observed variance explained. CONCLUSION This study contributes novel insights into the genetic architecture of kidney function in SSA populations, emphasizing the need for conducting genetic research in diverse cohorts. The identified loci provide a foundation for future investigations into the genetic susceptibility to chronic kidney disease in underrepresented African populations.
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Fiseha T, Ekong NE, Osborne NJ. Chronic kidney disease of unknown aetiology in Africa: A review of the literature. Nephrology (Carlton) 2024; 29:177-187. [PMID: 38122827 DOI: 10.1111/nep.14264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/25/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023]
Abstract
During the last two decades, an epidemic of a severe form of chronic kidney disease (CKD) unrelated to traditional risk factors (diabetes and hypertension) has been recognized in low- to middle-income countries. CKD of unknown aetiology (CKDu) mainly affects young working-age adults, and has become as an important and devastating public health issue. CKDu is a multifactorial disease with associated genetic and environmental risk factors. This review summarizes the current epidemiological evidence on the burden of CKDu and its probable environmental risk factors contributing to CKD in Africa. PubMed/Medline and the African Journals Online databases were searched to identify relevant population-based studies published in the last two decades. In the general population, the burden of CKD attributable to CKDu varied from 19.4% to 79%. Epidemiologic studies have established that environmental factors, including genetics, infectious agents, rural residence, low socioeconomic status, malnutrition, agricultural practise and exposure to agrochemicals, heavy metals, use of traditional herbs, and contaminated water sources or food contribute to the burden of CKD in the region. There is a great need for epidemiological studies exploring the true burden of CKDu and unique geographical distribution, and the role of environmental factors in the development of CKD/CKDu.
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Affiliation(s)
- Temesgen Fiseha
- Department of Clinical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | | | - Nicholas J Osborne
- Faculty of Medicine, School of Public Health, The University of Queensland, Brisbane, Queensland, Australia
- School of Population Health, University of New South Wales, Sydney, New South Wales, Australia
- European Centre for Environment and Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall, UK
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Mtingi-Nkonzombi L, Manning K, Du Toit T, Muller E, Redd AD, Freercks R. The state of kidney replacement therapy in Eastern Cape Province, South Africa: A call to action. S Afr Med J 2023. [DOI: 10.7196/samj.2023.v113i4.313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Abstract
Background. South Africa (SA) is one of the most financially unequal countries in the world. This situation is highlighted by disparateaccess to healthcare, particularly provision of kidney replacement therapy (KRT). Unlike the private sector, public sector access to KRT is highly rationed, and patient selection is based on suitability for transplantation and capacity.Objectives. To investigate the state of the KRT service in Eastern Cape Province, SA, by analysing access to and provision of KRT in theprovince for individuals with end-stage kidney disease, as well as disparities between the private and public healthcare systems.Methods. This was a retrospective descriptive study to examine KRT provision and temporal trends in the Eastern Cape. Data were obtained from the South African Renal Registry and the National Transplant Waiting List. KRT provision was compared between the three main referral centres, in Gqeberha (formerly Port Elizabeth), East London and Mthatha, and between the private and public healthcare systems.Results. There were 978 patients receiving KRT in the Eastern Cape, with an overall treatment rate of 146 per million population (pmp).The treatment rate for the private sector was 1 435 pmp, compared with 49 pmp in the public sector. Patients treated in the private sector were older at initiation of KRT (52 v. 34 years), and more likely to be male, to be HIV positive, and to receive haemodialysis as their KRT modality. Peritoneal dialysis was more commonly used in Gqeberha and East London as the first and subsequent KRT modality, compared with Mthatha. There were no patients from Mthatha on the transplant waiting list. There were no waitlisted HIV-positive patients in the public sector in East London, compared with 16% of the public sector patients in Gqeberha. The kidney transplant prevalence rate was 58 pmp in the private sector and 19 pmp in the public sector, with a combined prevalence of 22 pmp, constituting 14.9% of all patients on KRT. We estimated the shortfall of KRT provision in the public sector to be ~8 606 patients.Conclusion. Patients in the private sector were 29 times more likely to access KRT than their public sector counterparts, who were onaverage 18 years younger at initiation of KRT, probably reflecting selection bias in an overburdened public health system. Transplantation rates were low in both sectors, and lowest in Mthatha. A large public sector KRT provision gap exists in the Eastern Cape and needs to be addressed urgently.
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