<html><head></head><body lang="en-GB"><div dir="ltr"><div>Dear Chrysostomos.</div><div><br></div><div>You error arises from the configuration of netmeta::pairwise(): you need to give your data in contrast form (one row for each comparison). Your 4-arm trial should contribute six rows in the dataframe, not one:</div><div><br></div><div>Topiramate 50mg(route1) vs Topiramate 50mg(route2)<div>Topiramate 50mg(route1) vs Topiramate 50mg(route3)</div><div><div>Topiramate 50mg(route1) vs Topiramate 100mg</div><div><div>Topiramate 50mg(route2) vs Topiramate 50mg(route3)</div><div><div>Topiramate 50mg(route2) vs Topiramate 100mg</div><div>Topiramate 50mg(route3) vs Topiramate 100mg</div><b></b><i></i><u></u><sub></sub><sup></sup><strike></strike></div><div><br></div><div>That being said, I cannot answer of the usefulness of such comparisons. You cannot pool the result from the three Topiramate groups to compare their total effect with the participants in the fourth group.</div></div></div></div><div><br></div><div>Hope I have helped,</div><div><br></div><div>Fani Apostolidou Kiouti, </div><div>Department of Hygiene, Medical School, Aristotle University of Thessaloniki </div></div><br></body></html>