Research contribution on cardiovascular disease remains low

Cardiovascular research output from African researchers over the past 50 years remains low, despite marked progress. The annual number of journal articles increased from four publications in 1971 to 3,867 in 2020, according to a study that scanned Web of Science and other sources and retrieved data of publications related to African authorship.

In global representation, the proportion of Africa’s cardiovascular research publications rose from 0.1% in 1971 to 3.1% in 2021, with an accelerated trend in the past decade.

The study ‘Fifty Years of Global Cardiovascular Research in Africa: A scientometric analysis, 1971 to 2021’ that was published in the Journal of the American Heart Association, or JAHA, noted that researchers retrieved 35,368 publications in cardiovascular research done in Africa or co-authored by researchers based on the continent.

That number of African publications, according to the study, represented 1.7% of the global cardiovascular research output for the five decades under review.

CVD not studied enough in Africa

The comprehensive study was conducted by nine researchers from Africa, the US and Germany with Dr Jean Jacques Noubiap, a medical scholar from Cameroon and currently a researcher at the Centre for Heart Rhythm Disorders at University of Adelaide in Australia, as the lead author.

The researchers found that, although Africa carries the largest proportion of the global burden of disease, it has the lowest research contributions on cardiovascular diseases, or CVD, a field that is related to the study of disorders that affect the heart and the blood vessels.

Noubiap and his associates pointed out that the continent is experiencing a surge in CVD. Over a million deaths in 2019 were attributed to the problem in Sub-Saharan Africa alone. “The rise in the prevalence of CVD represents health and socio-economic challenge for African countries,” the researchers stated.

In this regard, CVD is expected to overtake infectious diseases as the leading cause of death in Africa by 2030. However, the continent is ill-prepared to cope with such an epidemic due to a lack of high-quality research that would provide guidance on how to make preventive healthcare decisions.

Six major conditions highlighted

The researchers found that most of the African publications on CVD were in six major domains, headed by coronary artery disease at 22.6%, heart failure (19.1%) and cerebrovascular disease, a group of conditions that affect blood flow and the blood vessels in the brain, at 11.9%. Articles on cardiomyopathy, a condition that makes it hard for the heart to pump blood to the rest of the body, stood at 8.3%; arrhythmias, disorders that cause irregular heartbeats, at 7.7%; and venous thromboembolism, a condition that occurs when a blood clot forms in a vein, was at 7%.

There were a smaller number of research publications on congenital heart disease (5.2%), pericardial disease (3.8%), rheumatic heart disease (3.6%), pulmonary hypertension (3.3%), non-rheumatic valvular disease (2.9%), endocarditis (2.6%) and peripheral arterial disease (1.9%).

In terms of country cardiovascular research output, South African authors produced 9,055 publications that represented 25.6% of Africa’s total output while their counterparts in Egypt recorded 7,777 publications, representing 22% of all research from the continent.

African cardiovascular research is highly skewed as the five leading countries – South Africa, Egypt, Nigeria, Tunisia and Morocco, accounted for about 75% of the publication share. Still, only 12 countries published more than 500 papers: South Africa (9,055) Egypt (7,777), Nigeria (2,824), Tunisia (2,352), Morocco (1,510), Ethiopia (984) and Ghana (829), Kenya (738), Algeria (679), Cameroon (673), Uganda (667) and Tanzania (619).

These countries produced 28,707 publications, accounting for over 80% of the continent’s cardiovascular research output during the period under review, while 24 countries produced fewer than 100 publications each, with 15 publishing less than 50 papers each. Countries with the least publications were Somalia (11), Chad (10), Lesotho (10), Comoros (7), and Djibouti (2).

International collaboration clusters

International collaboration appeared to be common, and the top non-African countries involved in co-authorships in Africa’s cardiovascular publications were the US, the UK, France, Germany and Australia, all countries that are leaders in biomedical research.

The researchers pointed out that collaboration clustering between African and non-African countries is influenced by colonial heritage and language, as well as historical and political ties. For instance, there were clusters of collaboration between France and French-speaking African countries such as Tunisia, Morocco, Algeria and Cameroon, while other clusters were formed between the UK and the US, and English-speaking African countries such as South Africa, Nigeria, Egypt, Ghana and Kenya.

Collaboration in Africa’s cardiovascular research authorship was also found to be driven by funding, whereby the US and the UK are key funders of both public and private research through the US National Institutes of Health, the UK’s Wellcome Trust, and the UK Medical Research Council.

In this regard, the level of international collaboration between African countries remains limited in comparison with their collaboration with non-African countries, although South Africa, Nigeria and Cameroon had the highest level of collaboration with other African countries.

Highlighting the top 200 most prolific cardiovascular researchers in Africa, the study noted that men represented 72.5% of the top authors that had published in the range of 26 to 376 papers.

South African women in the lead

Karen Sliwa, a professor of internal medicine and the director of the Hatter Institute for Cardiovascular Research in Africa at the University of Cape Town (UCT) and one of the general authors of the JAHA study, was the most prolific researcher with 376 papers while Professor Aletta Schutte, formerly of the North-West University in South Africa and currently at the University of New South Wales in Australia, was second with 271 publications. The late Professor Bongani Mayosi of UCT came in third with 267 publications.

Other researchers that had more than 200 publications included the late Professor Lionel Opie, co-founder of the Hatter Institute, who published 261 papers, and Professor Andre Pascal Kengne, a unit director at the South African Medical Research Council and an academic member of UCT who published 237 articles.

During the period under review, South Africa had cemented its leadership in Africa’s cardiovascular research as it had 51.5% of the top 200 most prolific authors, while Tunisia had 18%, against Egypt’s 7% and Nigeria’s 3%. Other countries that had researchers among the top 200 most prolific authors were Algeria, Cameroon, the Democratic Republic of Congo, Ghana, Kenya, Mozambique, Morocco, Senegal, Mozambique and Uganda, albeit in small numbers.

With 26 researchers each, UCT and the University of the Witwatersrand (Wits) were the universities with the highest number of the most prolific cardiovascular researchers in Africa. More than 25% of the most prolific cardiovascular researchers in Africa were affiliated with the two universities, the most highly-rated cardiovascular research institutions on the continent.

Other universities that had a good number of such cadres included the University of Monastir (14) of Tunisia and South Africa’s North-West University (13) and the University of KwaZulu- Natal (7).

High-quality papers cited

Based on the h-index, a standard metric that measures an author’s quality of publications in terms of the number of times they have been cited, showed that most of the high-quality papers in Africa’s cardiovascular research were co-authored by researchers from the US, South Africa, the UK, Germany, Canada, Australia, Italy, France and the Netherlands.

South Africa, Egypt, Nigeria, Kenya and Tunisia were the five African countries with the highest h-index while Seychelles led in the highest number of publications per one million inhabitants.