Data sources: The authors of this rapid review did not disclose which electronic databases were included in their literature search. The inclusion and exclusion criteria for the data sources are not reported in the manuscript.
Study selection: The authors included six studies on the effectiveness of hydroxychloroquine or chloroquine for the prevention and treatment of COVID-19 in humans. Studies comprised of two randomised controlled trials, two non-randomised trials both of which were non-blinded and open-label and one that was uncontrolled, a prospective cohort study and an interim report. The authors did not report details of any studies that were excluded.
Data extraction and synthesis: The data extraction methodology was not reported and it is unclear if the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were followed. Treatment regimens and the study outcomes were extracted where available and overall findings were presented in a table. There were no comparable outcome measures; therefore, results were deemed unsuitable to combine and no statistical analyses were carried out. A narrative synthesis of each study is presented.
Results: The results of the studies in this rapid review are difficult to quantify as each study had different outcome parameters. Due to the heterogeneity of the studies, results were not combined, and no statistical analysis was carried out. Narrative synthesis of each of the included studies identified important and significant limitations, precluding the studies from demonstrating a statistically significant difference in outcomes.
Conclusions: This review highlights the urgent need for more high quality evidence on the use of hydroxychloroquine and chloroquine in the prevention and treatment of COVID-19. The results of the studies included should be interpreted with caution due to the weak supporting data and numerous methodological limitations. The authors suggested that the studies be viewed as hypothesis-generating and should not be used in decision making around the recommendations and guidelines in the prevention and treatment of COVID-19. There are currently several ongoing randomised controlled trials looking at the effectiveness and efficacy of these drugs on COVID-19. It is hoped the outcome of these studies can help guide future recommendations and national guidelines.