Dyslipidaemia in Africa—comment on a recent systematic review – Authors' reply
Authors: Jean Jacques Noubiap, Eric Vounsia Balti, Jean Joel Bigna, Justin B Echouffo-Tcheugui, André Pascal Kengne
Journal: The Lancet Global Health (2018)

We thank Robert Newton for his Correspondence, which has provided us with the opportunity to correct an oversight. We agree that our review1Noubiap JJ Bigna JJ Nansseu JR et al.Prevalence of dyslipidaemia among adults in Africa: a systematic review and meta-analysis.Lancet Glob Health. 2018; 6: e998-e1007Summary Full Text Full Text PDF PubMed Scopus (70) Google Scholar mistakenly included three articles from the same study done in Uganda.3Asiki G Murphy GA Baisley K et al.Prevalence of dyslipidaemia and associated risk factors in a rural population in south-western Uganda: a community based survey.PLoS One. 2015; 10: e0126166Crossref PubMed Scopus (36) Google Scholar, 4Murphy GA Asiki G Ekoru K et al.Sociodemographic distribution of non-communicable disease risk factors in rural Uganda: a cross-sectional study.Int J Epidemiol. 2013; 42: 1740-1753Crossref PubMed Scopus (50) Google Scholar After further cross-checking of the 181 studies initially included in the review, we identified two additional duplicates.5Olamoyegun MA Oluyombo R Asaolu SO Evaluation of dyslipidemia, lipid ratios, and atherogenic index as cardiovascular risk factors among semi-urban dwellers in Nigeria.Ann Afr Med. 2016; 15: 194-199Crossref PubMed Scopus (35) Google Scholar, 6Oluyombo R Akinwusi PO Olamoyegun MO et al.Clustering of cardiovascular risk factors in semi-urban communities in south-western Nigeria.Cardiovasc J Afr. 2016; 27: 322-327Crossref PubMed Scopus (15) Google Scholar, 7Nwose EU Oguoma VM Bwititi PT Richards RS Metabolic syndrome and prediabetes in Ndokwa community of Nigeria: preliminary study.N Am J Med Sci. 2015; 7: 53-58Crossref PubMed Scopus (8) Google Scholar, 8Oguoma VM Nwose EU Ulasi II et al.Maximum accuracy obesity indices for screening metabolic syndrome in Nigeria: a consolidated analysis of four cross-sectional studies.Diabetes Metab Syndr. 2016; 10: 121-127Crossref PubMed Scopus (10) Google Scholar We conducted new analyses including only data reported in the articles with highest sample size among the duplicates identified (table). The pooled prevalence of dyslipidaemia in the general population from population-based studies was 25·5% (95% CI 20·0–31·4; corrected from 23·6%, 18·4–29·6) for elevated concentrations of total cholesterol with a cutoff of at least 5·2 mmol/L, 37·4% (29·4–45·7; corrected from 41·1%; 33·0–49·2) for low concentrations of HDL cholesterol with a cutoff of less than 1·0 mmol/L, 28.6% (15·8–43·5; corrected from 25·7%, 16·2–36·6) for elevated concentrations of LDL cholesterol with a cutoff of at least 3·3 mmol/L, and 17·0% (11·9–22·7; corrected from 16·5%, 11·8–21·6) for elevated concentrations of triglycerides with a cutoff of at least 1·7 mmol/L (table). The new results are not different from those in the main manuscript1Noubiap JJ Bigna JJ Nansseu JR et al.Prevalence of dyslipidaemia among adults in Africa: a systematic review and meta-analysis.Lancet Glob Health. 2018; 6: e998-e1007Summary Full Text Full Text PDF PubMed Scopus (70) Google Scholar in terms of magnitude of prevalence estimates; thus, the message of our article is unchanged.TablePooled prevalence of dyslipidaemia with various cutoffs in the general population from community-based studies in AfricaPrevalenceStudiesParticipantsI2HpheterogeneitypEgger testpdifferenceTotal cholesterol5·2 mmol/L25·5% (20·0–31·4)3770–29699·7 (99·6–99·7)17·2 (16·5–17·9)<0·00010·070<0·00016·5 mmol/L11·0% (7·1–15·5)2030–05499·3 (99·2–99·4)12·4 (11·5–13·3)<0·00010·943··HDL cholesterol0·9 mmol/L19·5% (10·5–30·6)6577198·9 (98·5–99·2)9·6 (8·2–11·3)<0·00010·8010·011·0 mmol/L37·4% (29·4–45·7)2734–78499·6 (99·5–99·6)15·6 (14·9–16·4)<0·00010·039··LDL cholesterol2·6 mmol/L21·3% (16·7–26·5)2183081·2 (19·9–95·6)2·30·021NA0·1873·3 mmol/L28·6% (15·8–43·5)1215–63899·7 (99·6–99·7)17·5 (16·3–18·8)<0·00010·009··4·0 mmol/L13·5% (5·7–24·0)5592199·1 (98·7–99·4)10·6 (8·9–12·5)<0·00010·484··Triglycerides1·7 mmol/L17·0% (11·9–22·7)3757–70199·7 (99·6–99·7)17·1 (16·5–17·9)<0·00010·762<0·00012·2 mmol/L12·0% (9·6–14·7)1227–82697·4 (96·6–98·1)6·3 (5·4–7·2)<0·00010·007··5·2 mmol/L5·0% (3·1–7·2)1441NANANANA··Data are % (95% CI), N, I2 (95% CI), or H (95% CI). Open table in a new tab Data are % (95% CI), N, I2 (95% CI), or H (95% CI). Newton also says he considers that a wide heterogeneity precludes pooled estimates from meta-analyses. In general, heterogeneity is inevitable in meta-analyses of observational studies and prevalence studies, particularly in Africa. This heterogeneity is also reflected in meta-analyses of African studies done by Newton and colleagues.9Namale G Kamacooko O Kinengyere A et al.Risk factors for hemorrhagic and ischemic stroke in sub-Saharan Africa.J Trop Med. 2018; 2018: 4650851Crossref PubMed Scopus (22) Google Scholar, 10Fox JM Mutalima N Molyneux E et al.Seroprevalence of HTLV-1 and HTLV-2 amongst mothers and children in Malawi within the context of a systematic review and meta-analysis of HTLV seroprevalence in Africa.Trop Med Int Health. 2016; 21: 312-324Crossref PubMed Scopus (20) Google Scholar It is improbable that several studies carried out in different populations by different investigators, with variable methodological approaches, will provide consistent results. The decision to pool estimates should be taken a priori, provided data are from studies fulfilling well predefined inclusion criteria. The high heterogeneity described in our meta-analysis does not invalidate its findings. When high heterogeneity is found, potential sources should be investigated. In our study, the substantial heterogeneity in the estimates was not explained by major study-level characteristics. In addition to presenting estimates at the continental level, we did various subgroup analyses, including at the regional level. Moreover, in the forest plots depicting pooled estimates, data are presented by country. In the context of these limitations, our findings are not overemphasised. The observed high prevalence in the general adult populations at the continental and country levels highlight the need for effective detection and treatment of dyslipidaemia in Africa. The data provided for each country can be used by local health authorities to design country-specific interventions for dyslipidaemia. We declare no competing interests. Dyslipidaemia in Africa—comment on a recent systematic reviewThe publication of the systematic review by Jean Jacques Noubiap and colleagues1 in The Lancet Global Health highlights two important issues. The first issue is the trend to systematically review data according to well established formula, but in the absence of a thorough understanding of the field and expertise. Many systematic reviews are produced by professional reviewers with little topic-specific knowledge. In Noubiap and colleagues'1 systematic review, data are presented including three studies from Uganda; however, these three articles cover the same study, although the focus of each article was different. Full-Text PDF Open AccessPrevalence of dyslipidaemia among adults in Africa: a systematic review and meta-analysisThe prevalence of dyslipidaemia is high in the general adult population in Africa. Ongoing efforts to reduce cardiovascular diseases in Africa should integrate effective detection and treatment of dyslipidaemia. Full-Text PDF Open Access