Genomic and environmental risk factors for cardiometabolic diseases in Africa: methods used for Phase 1 of the AWI-Gen population cross-sectional study

ABSTRACT

There is an alarming tide of cardiovascular and metabolic disease (CMD) sweeping across Africa. This may be a result of an increasingly urbanized lifestyle characterized by the growing consumption of processed and calorie-dense food, combined with physical inactivity and more sedentary behaviour. While the link between lifestyle and public health has been extensively studied in Caucasian and African American populations, few studies have been conducted in Africa. This paper describes the detailed methods for Phase 1 of the AWI-Gen study that were used to capture phenotype data and assess the associated risk factors and end points for CMD in persons over the age of 40 years in sub-Saharan Africa (SSA). We developed a population-based cross-sectional study of disease burden and phenotype in Africans, across six centres in SSA. These centres are in West Africa (Nanoro, Burkina Faso, and Navrongo, Ghana), in East Africa (Nairobi, Kenya) and in South Africa (Agincourt, Dikgale and Soweto). A total of 10,702 individuals between the ages of 40 and 60 years were recruited into the study across the six centres, plus an additional 1021 participants over the age of 60 years from the Agincourt centre. We collected socio-demographic, anthropometric, medical history, diet, physical activity, fat distribution and alcohol/tobacco consumption data from participants. Blood samples were collected for disease-related biomarker assays, and genomic DNA extraction for genome-wide association studies. Urine samples were collected to assess kidney function. The study provides base-line data for the development of a series of cohorts with a second wave of data collection in Phase 2 of the study. These data will provide valuable insights into the genetic and environmental influences on CMD on the African continent.

KEYWORDS:

• Cardiometabolic disease
• African populations
• burden of disease
• H3Africa
• AWI-Gen

Responsible Editor

Peter Byass, Umeå University, Sweden

Special Issue BMI distribution across African communities

Responsible Editor

Peter Byass, Umeå University, Sweden

Special Issue BMI distribution across African communities

Acknowledgments

This study would not have been possible without the generosity of the participants who spent many hours responding to questionnaires, being measured and having samples taken. We wish to acknowledge the sterling contributions of our field workers, phlebotomists, laboratory scientists, administrators, data personnel and all other staff who contributed to the data and sample collections, processing, storage and shipping. We would like to acknowledge the contributions of Brian Njamwea and Sekgothe Dikotope, who sadly passed away during AWI-Gen Phase 1, and who would otherwise be named as co-authors on this paper. Investigators responsible for the conception and design of the original AWI-Gen study include the following: Michèle Ramsay (PI, Wits), Osman Sankoh (co-PI, INDEPTH), Alisha Wade, Stephen Tollman and Kathleen Kahn (Agincourt), Marianne Alberts (Dikgale), Catherine Kyobutungi (Nairobi), Halidou Tinto (Nanoro), Abraham Oduro (Navrongo), Shane Norris (Soweto), and Scott Hazelhurst, Nigel Crowther, Himla Soodyall and Zané Lombard (Wits). The authors would like to acknowledge each of the following investigators for the significant contributions made to this research: Agincourt: Ryan Wagner and Sulaimon Afolabi; Dikgale: Ian Cook and Sam Ntuli; Nairobi: Stella Muthuri; Nanoro: Toussaint Rouamba and Moussa Lingani; Soweto: Nomses Baloyi, Juliana Kagrana, Richard Munthali and Yusuf Guman; University of the Witwatersrand/National Health Laboratory Service: Venesa Pillay; Wits Clinical Laboratory Services: Linda Bethlehem. The data will be made available in the European Genome-phenome Archive (EGA) under the set of projects related to the Human Heredity and Health in Africa (H3Africa) Consortium. DNA samples will be stored in the South African H3Africa Biobank. Details concerning access to data and DNA can be found in the document titled ‘H3Africa Data and Biospecimen Access Committee Guidelines’, available in the consortium documents section of the H3Africa website (www.h3africa.org).

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethics and consent

This study was approved by the Human Research Ethics Committee (Medical) of the University of the Witwatersrand (Wits) (protocol number M121029), renewed in 2017 (protocol number M170880). The SBIMB Biobank was approved by the Wits Biobank Ethics Committee, approval identification number BEC20140302. In addition, each research site approval from their local ethics review board prior to commencing any participant-related activities (see detail in the papers in this special issue).

Paper context

This paper describes in detail the methods used to collect data and biospecimens for Phase 1 of the AWI-Gen study, which aims to examine genetic and environmental factors related to cardiometabolic disease (CMD) in Africans. Understanding the unique risk factor profile and long-term health consequences of rapidly changing environmental and demographic conditions, in the context of African genome variation, will inform public health interventions to mitigate the chronic burden of disease, especially for CMD.

Supplementary Material

Supplemental data for this article can be accessed here.

Additional information

Funding

The AWI-Gen Collaborative Centre is funded by the National Human Genome Research Institute (NHGRI), Office of the Director (OD), Eunice Kennedy Shriver National Institute Of Child Health & Human Development (NICHD), the National Institute of Environmental Health Sciences (NIEHS), the Office of AIDS research (OAR) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), of the National Institutes of Health (NIH) under award number U54HG006938 and its supplements, as part of the H3Africa Consortium. Additional funding was leveraged from the Department of Science and Technology, South Africa, award number DST/CON 0056/2014, and from the African Partnership for Chronic Disease Research (APCDR).

Notes on contributors

Stuart A. Ali

All authors were involved with developing the methods used in the study. SA and CS drafted the initial version of this manuscript with additional text provided by the co-authors. All authors have been provided the opportunity to revise and critically review the manuscript, and each accepts accountability for the accuracy or integrity of any part thereof.