DOI: 10.17037/data.00002178
title: Study investigating the clinical manifestations of Rift Valley fever in humans: Systematic review and meta-analysis

description: Data extraction in this study was aimed at achieving three main purposes: 1) obtain data that describe the characteristics of the included studies, 2) obtain data for assessing the quality of included studies, and 3) obtain data for synthesizing the frequency and duration of clinical manifestations and duration of illness since onset to diagnosis. Information was abstracted on the characteristics of eligible studies including first author’s surname, year of publication, type of article (abstract or full text), list of countries where the study was conducted, information on the study design (cohort, cross sectional/outbreak investigation, intervention studies, case series, reviews); demographics (number of participants that were enrolled, age, sex and nationality); laboratory tests used to confirm diagnosis of RVF (enzyme linked immunosorbent assay or ELISA (IgM & IgG), real-time polymerase chain reaction (rtPCR) or quantitative polymerase chain reaction (qPCR), plaque reduction neutralisation test (PRNT) and focus reduction neutralisation test (FRNT) or other serological and viral antigen tests etc). Data on the number or proportion that had co-infections and type of co-infection such as hepatitis B, malaria, schistosomiasis etcetera were also captured. Rift Valley fever presents among humans in form of clinical syndromes including the general febrile syndrome, hepatic or abdominal syndrome, encephalitis syndrome, visual syndrome and haemorrhagic syndrome. Data was collected on several RVF clinical manifestations in humans for which proportion or description of symptoms was recorded. Data was also extracted on the frequency and levels of each laboratory parameter reported.
description: Electronic bibliographic databases including Medline/PubMed, Embase, Global Health and Web of Science were searched to identify relevant studies. Two people independently reviewed the abstracts of relevant papers to determine study eligibility and selected the articles for full text review and data extraction. All records from the search and selection process were captured directly into a systematic review flow schema. Data from eligible studies was extracted into two excel sheets. The two reviewers that assessed eligibility were the same persons that extracted the records from the papers. Discrepant entries between the two reviewers were resolved through discussions which were held face to face, by telephone, skype or email and the final agreed records were summarised on the excel sheets. Where two or more manuscripts report data from the same study, these were considered as one study and data was extracted on clinical manifestations that do not duplicate. The number of articles obtained through searching, number selected and number from which data was extracted was recorded and presented in a flow diagram. The studies from which data was extracted were identified by the first author’s surname. Data from the excel sheets was imported into stata analysis software. Where two or more studies were available for a particular clinical manifestation, pooled proportions of patients were presented with the parameter and their 95% confidence intervals estimated using random effects models. Sensitivity analysis was done to check the effect of study quality and study design on the pooled proportion. Forest plots were drawn where two or more studies reported a particular clinical manifestation and these were summarised by patient source.