Comparative efficacy of drugs for treating giardiasis: a systematic update of the literature and network meta-analysis of randomized clinical trials

Background: Giardiasis is the commonest intestinal protozoal infection worldwide. The current first-choice therapy is metronidazole. Recently, other drugs with potentially higher efficacy or with fewer and milder side effects have increased in popularity, but evidence is limited by a scarcity of randomized controlled trials (RCTs) comparing the many treatment options available. Network meta-analysis (NMA) is a useful tool to compare multiple treatments when there is limited or no direct evidence available. Objectives: To compare the efficacy and side effects of all available drugs for the treatment of giardiasis. Methods: We selected all RCTs included in systematic-reviews and expert reviews of all treatments for giardiasis published until 2014, extended the systematic literature search until 2016, and identified new studies by scanning reference lists for relevant studies. We then conducted a NMA of all available treatments of giardiasis by comparing parasitological cure (efficacy) and side effects. Results: We identified 60 RCTs from 58 reports (46 from published systematic-reviews, 8 from reference lists and 4 from the updated systematic search). Data from 6,714 patients, 18 treatments and 42 treatment comparisons were available. Tinidazole was associated with higher parasitological cure than metronidazole (RR: 1.23, 95% CI: 1.12-1.35) and albendazole (RR: 1.35, 95% CI: 1.21-1.50). Taking into consideration clinical efficacy, side effects and size of the evidence, tinidazole was found to be the most effective drug. Conclusions: We provide additional evidence that tinidazole single dose is the best available treatment of giardiasis in symptomatic and asymptomatic children and adults