Epidemiological data on systemic lupus erythematosus in native sub-Saharan Africans

Multiethnic studies conducted outside sub-Saharan Africa identify African Black people as the highest-risk group for morbidity and mortality among the 5,000,000 people who are affected by lupus globally. In the meantime, there have bee few attempts to summarize lupus data from sub-Saharan africa. We therefore conducted a systematic review and meta-analysis addressing systemic lupus erythematosus in Native sub-Saharan Africans. This paper both serves as repository for and describes the data obtained by qualitative and quantitative synthesis, notably the pooled prevalence of autoantibodies, the pooled frequency of cumulative drug use, the prevalence of comorbidities/complications and the mortality rate in Native sub-Saharan Africans with systemic lupus erythematosus. These data are interpreted in the research article titled “Systemic lupus erythematosus in Native sub-Saharan Africans: a systematic review and meta-analysis” (Essouma et al., 2019) [1].


Data description
We herein report the pooled prevalence rates of autoantibodies ( Fig. 1), the pooled frequencies of cumulative drug use (Fig. 2), the prevalence of comorbidities/complications (Table 1) and the pooled mortality rate (Fig. 3). The main search strategy used (in PUBMED) to obtain these data is displayed in Table 2 and Fig. 4 describes the study selection process. Table 3 summarizes the characteristics of the overall 15 included studies [2e16] whereas Table 4 summarizes only the studies included in the mortality analysis [4,6e9,14,16].

Experimental design, materials, and methods
Searched databases and search strategy Specifications Table   Subject Medicine and Dentistry Specific subject area Immunology, Allergology and Rheumatology Type of data Data presented in tables and figures How data were acquired Systematic literature search Data format Raw and analyzed data Parameters for data collection We collected data regarding both included studies (methods, setting, period, systemic lupus erythematosus prevalence, characteristics, drugs and outcome) and articles where these data were published (year of publication, name of the first author, journal) Description of data collection The above-mentioned data were extracted from the full-texts of eligible articles and cross-checked to ensure that there was no missing information Data source A comprehensive search of PubMed, Excerpta Medica database (EMBASE), Web of Science, African Journals Online, and Global Index Medicus was conducted to identify all relevant articles published from January 1, 2008 to October 7, 2018, without any language restriction. We considered recent studies to have the current and updated clinical overview of systemic lupus erythematosus in the region. We conceived and applied a search strategy based on the combination of relevant terms. The main search strategy in PubMed was adapted for the search in the other databases. A manual search that consists of scanning reference lists of eligible studies and relevant reviews was performed to identify any studies missed during the review process or by the search strategy.
The titles and abstracts of the retrieved papers were independently screened by two investigators (ME and JRN) and the full-texts of papers deemed potentially eligible were further assessed for final inclusion. All discrepancies for study selection were resolved through discussion or with the arbitrage of a third investigator.
Criteria for considering studies for the review ➢ Types of studies Observational studies including cross-sectional, case-control and cohort studies, as well as case series. We did not consider case reports, commentaries, review articles and letters to the editor.

➢ Types of participants
We considered studies involving African Black people (or multiethnic groups with possibility to extract information for the African Black people) living in sub-Saharan Africa regardless of the age and gender. Studies were excluded if: (1) they included multiethnic groups with no possibility to extract informations regarding only the African Black people (2) they only included a specific group of lupus patients i.e. lupus nephritis, neuropsychiatric lupus, cutaneous lupus, lupus pericarditis, lupus myocarditis, lupus in pregnant women (3) they included patients with overlapping syndromes.

➢ Condition
The classification for systemic lupus erythematosus was based on the 1982 American College of Rheumatology and/or revised 1997 American College of Rheumatology criteria [17,18].

➢ Outcomes of interest
The following outcomes were analyzed: systemic lupus erythematosus prevalence; demographic, clinical and immunological characteristics of systemic lupus erythematosus; frequencies of cumulative drug use for the treatment of systemic lupus erythematosus and its complications; outcome measures of systemic lupus erythematosus.

Data extraction and management
The data were extracted by two investigators (ME and JJB) using a preconceived, piloted and standardized data abstraction form. The following data were extracted and cross-checked to ensure that there was no missing information: name of the first author, year of publication, study design, period of recruitment of the study population, setting (country, unique/multiple site[s]), locality (urban/rural), sampling method, systemic lupus erythematosus diagnostic criteria and the outcomes of interest.

Antimalarials
We used an adapted version of the tool developed by Hoy and colleagues [19] to assess the methodological quality of included studies. Three investigators (JJB, ME and FTAE) independently ran the assessment. Discrepancies were discussed and resolved by these investigators. Cohen's k statistics were used for inter-rater agreements between investigators regarding study inclusion and for the assessment of the methodological quality of the included studies.

Data synthesis and analysis
The quantitative synthesis was done using the 'meta' packages of the R statistical software (version 3.5.1, The R Foundation for statistical computing, Vienna, Austria). We used the reference method for prevalence synthesis suggested by Barendregt and colleagues [20]. The prevalence of systemic lupus erythematosus and systemic lupus erythematosus autoantibodies, the frequencies of cumulative drug use and the mortality rate were recalculated based on crude numerators and denominators provided Table 1 Prevalence of comorbidities and complications in Native sub-Saharan Africans with systemic lupus erythematosus.

Complications/comorbidities
Prevalence, range % Infections [5,6,8,9,11,12] 4.3e68.7 Cardiovascular diseases and risk factors -Heart failure [8] 33.3 -Stroke [6,10,12] 5.1e6.8 -Peripheral vein thrombosis [8,11] 2 e4.3 -Diabetes mellitus [6,12] 5.1e18.7 -Hypertension [2,6,9] 10.3e19.6 Chronic kidney disease [6,10,12,16] 6.2e9.4 Any aseptic osteonecrosis [6,10] 2.6e6.2    Tome" OR Senegal OR Seychelles OR "Sierra Leone" OR Somalia OR "South Africa" OR "St Helena" OR Sudan OR Swaziland OR Tanzania OR Togo OR Tunisia OR Uganda OR "Western Sahara" OR Zaire OR Zambia OR Zimbabwe OR "Central Africa" OR "Central African" OR "West Africa" OR "West African" OR "Western Africa" OR "Western African" OR "East Africa" OR "East African" OR "Eastern Africa" OR "Eastern African" OR "North Africa" OR "North African" OR "Northern Africa" OR "Northern African" OR "South African" OR "Southern Africa" OR "Southern African" OR "sub Saharan Africa" OR "sub Saharan African" OR "subSaharan Africa" OR "subSaharan African" #3 #1 AND #2  by individual studies. To minimize the effect of studies with extremely small or extremely large prevalence estimates on the overall estimate, the variance of study-specific prevalence was stabilized with the Freeman-Tukey double arcsine transformation before pooling the data with the random effects meta-analysis model [20]. Heterogeneity was assessed by the chi-square test on Cochrane's Q statistic, and quantified by I 2 values. Low, moderate and high heterogeneity were considered for I 2 values of 25%, 50% and 75% respectively. The quality of the included studies is described in Table 3. The Egger's test was used to assess the presence of publication bias, and a statistically significant publication bias was considered for p-values < 0.1. We decided a priori that if we find publication bias, we will do no adjustment in regard, since we believed that the prevalence estimates of interest would likely be published even if they are substantially different from the previously reported estimates.