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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 3, May/June 2016
AFRICA
195
to analyse macro-level collaboration in the region. Specifically,
the study uses citation and network analyses to: (1) examine the
trends in scientific output and collaborative research patterns in
CVR in SSA; (2) identify the top countries in SSA involved in
collaborative CVR within the region and globally; and (3) assess
the scientific impact of collaborative CVR in SSA.
Methods
Bibliographic data were sourced from the Web of Science of
Thompson Reuters. A search procedure was developed to
retrieve the relevant publications for analysis. The databases
included in the search included: Science Citation Index Expanded
(SCI-EXPANDED), Conference Proceedings Citation Index
– Science (CPCI-S), Conference Proceedings Citation Index –
Social Science&Humanities (CPCI-SSH) andArts &Humanities
Citation Index (A&HCI). The publication period was restricted
to 2005 to 2014. A set of key words for cardiovascular research
was used for the search of the title, keyword and abstract fields.
15
The list of the 47 countries that constitute sub-Saharan Africa
was obtained from the World Bank
16
and used as part of the
advanced search protocol. Citation data were obtained for all the
retrieved records by using the Create Citation Report function in
Web of Science.
Pre-processing of the Web of Science data was done in
Microsoft Excel. Country names were extracted from each
author’s affiliation and saved with accompanying attribute data,
such as year and type of publication. The resulting flat file was
merged with citation data from Web of Science using unique
identifiers for each publication. Duplicate country names, which
occurred where co-authors were from the same country, were
eliminated for each publication using macros within Microsoft
Excel.
After cleaning, a total of 1 569 publications from 2005–2014
were available for analysis. The dataset was then split into two
for subsequent citation and network analyses: one with single
SSA country publications (
n
=
783) and another with multi-
country publications (
n
=
786). The multi-country dataset was
filtered to show only countries within SSA, to enable analysis of
collaboration patterns within the region. For network analysis
using this SSA-specific dataset, all publications with only one
SSA country were excluded. A total of 75 publications were
obtained, which included collaborations between multiple SSA
countries.
Data analysis
Research output was assessed using number of publications,
disaggregated by region or country and by single or joint country
authorship. The trend in research output was determined and
illustrated over the 10-year period. The instances of collaboration
were determined from adjacency matrices and used to determine
the top 10 SSA countries involved in cardiovascular research
collaboration and the top six countries outside the SSA with
which these collaborations occurred. Citation analysis was done
by examining the trend in citation rates in single-country- and
multi-country-authored publications across the 10-year period.
Patterns of international collaboration in cardiovascular
research involving SSA countries were analysed using traditional
network analysis methodologies. The co-occurrence of countries
in the affiliation field of publications was considered an instance
of collaboration between the two countries. Co-authorship at the
macro level is considered an effective approach to the analysis of
research collaboration between countries.
10
Preparation of datasets for network analysis involved
creating adjacency matrices of countries reflecting instances
of collaboration. Adjacency matrices were created using Visual
Basic scripts run in Microsoft Excel, and used in the analysis of
instances of collaboration within SSA. NodeXL, an open-source
network analysis and visualisation application, was used for
creating the network graph.
17
Network data were uploaded into
NodeXL as edge lists, i.e. a two-column list of country pairs that
collaborated in publications. The network graph used to visualise
international collaboration in CVR within SSA was created
using the Harel-Koren fast multiscale algorithm.
Results
Cardiovascular research output
A total of 88 cardiovascular research publications with
authorship in SSA were indexed in the Web of Science in 2005.
There was a gradual increase to 225 publications in 2014. The
trend for the fraction of CVR publications that involved multiple
countries was from 37 in 2005 to 124 in 2014. There were eight
CVR publications that involved multiple SSA countries in 2005,
with a slight increase to 16 in 2014. Overall, the number of
publications involving multiple SSA countries over the 10-year
period accounted for less than 10% of the total number of multi-
country publications that included at least one SSA country. The
number of publications in the field with authorship from a single
SSA country rose from 51 in 2005 to 101 in 2014 (not shown in
Fig. 1). These data reflect minimal country-level collaboration in
CVR in SSA and very limited growth in co-authorships across
country borders over the last decade. The trend in cardiovascular
research output in SSA is shown in Fig. 1.
Table 1 shows the cardiovascular research output by the
top 10 countries in SSA and the percentage of publications
that involved collaboration with other countries within or
250
200
150
100
50
0
2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Year
Number of publications
SSA + International (multi)
SSA (multi)
SSA + International (single and multi)
Fig. 1.
Trend in the number of publications in CVR with author-
ship from countries in SSA, 2005–2014. Single refers to
publications with only one SSA country in its affiliations;
multi refers to publications with more than one country
in its affiliations but including at least one SSA country.
International is used to refer to all countries outside SSA.