Soil-transmitted helminth infections in South America

Abstract

Frédérique Chammartin and colleagues' systematic review1Chammartin F Scholte RGC Guimarães LH Tanner M Utzinger J Vounatsou P Soil-transmitted helminth infection in South America: a systematic review and geostatistical meta-analysis.Lancet Infect Dis. 2013; 13: 507-518Summary Full Text Full Text PDF PubMed Scopus (89) Google Scholar and geostatistical meta-analysis aimed to produce high-resolution estimates of the risk and number of people infected with Ascaris lumbricoides, Trichuris trichiura, and hookworm across South America. According to PRISMA guidelines,2Liberati A Altman DG Tetzlaff J et al.The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration.PLoS Med. 2009; 6: e1000100Crossref PubMed Scopus (9479) Google Scholar the conduct of systematic reviews consists of several explicit and reproducible steps that have to be available to readers. However, two issues with the methods and results of Chammartin and colleagues' study could compromise confidence in the findings. First, in the search strategy, Chammartin and colleagues did not include important databases of Latin America or South America origin such as Latin America and the Caribbean Literature on Health Sciences (LILACS) or Scientific Electronic Library Online (SciELO). According to this systematic review, no data were available for Uruguay. However, replication of the Article's search strategy in regional databases for Uruguay identified one potentially relevant report3Acuña AM DaRosa D Colombo H et al.Parasitosis intestinales en guarderías comunitaris de Montevideo.Rev Med Uruguay. 1999; 15: 24-33Google Scholar in a journal not indexed in Pubmed, but in LILACS and SciELO. Exclusion of LILACS and SciELO is a database bias that could lead to false conclusions. For example, inclusion of only articles from MEDLINE and not LILACS generated a variation in the value of the odds ratio in a systematic review of Chagas disease.4Sinha MK Montir VM Reporting bias and other biases affecting systematic reviews and meta-analyses: a methodological commentary.Expert Rev Pharmacoecon Outcomes Res. 2006; 6: 603-611Crossref PubMed Scopus (8) Google Scholar Readers of systematic reviews should be aware of the possibility of reporting bias and other biases that might limit the quality of these reviews.4Sinha MK Montir VM Reporting bias and other biases affecting systematic reviews and meta-analyses: a methodological commentary.Expert Rev Pharmacoecon Outcomes Res. 2006; 6: 603-611Crossref PubMed Scopus (8) Google Scholar Even though the investigators could have reasons for the omission of the databases from their systematic review, they should be transparent about key decisions such as this and describe them for readers.2Liberati A Altman DG Tetzlaff J et al.The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration.PLoS Med. 2009; 6: e1000100Crossref PubMed Scopus (9479) Google Scholar Second, in the results the investigators mentioned that reports included in the systematic review were uploaded into the free open-access database Global Neglected Tropical Disease (GNTD). Although every article is well described in this database, it is difficult for the readers to know which of them is included in the systematic review because of the absence of a section in both the systematic review and the GNTD database where the articles included in the systematic review are explicitly mentioned. We decided to download information from the GNTD database for all articles related to the countries included in the systematic review; 181 articles were available (appendix). We applied the selection criteria and 14 articles were excluded because they were hospital-based surveys or did not include any prevalence data for A lumbricoides, T trichura, or hookworm infection, leaving 167 articles containing relevant prevalence data. Our result differs from the systematic review's results—eg, for Paraguay only one article is uploaded but Chammartin and colleagues reported two. We agree with Lissete van Lieshout and Maria Yazdanbakhsh's Comment5van Lieshout L Yazdanbakhsh M Landscape of neglected tropical diseases: getting it right.Lancet Infect Dis. 2013; 13: 469-470Summary Full Text Full Text PDF PubMed Scopus (12) Google Scholar that Chammartin and colleagues use robust and cutting-edge statistical methods; however, we question the reliability of the data produced and whether these data represent all the information reported in South America. We declare that we have no conflicts of interest. Download .pdf (.16 MB) Help with pdf files Supplementary appendix Soil-transmitted helminth infection in South America: a systematic review and geostatistical meta-analysisOur findings offer important baseline support for spatial targeting of soil-transmitted helminthiasis control, and suggest that more information about the prevalence of soil-transmitted helminth infection is needed, especially in countries in which we estimate prevalence of infection to be high but for which current data are scarce. Full-Text PDF