To determine the reporting quality of systematic review (SR) abstracts presented at World Congresses on Pain (WCPs) and to quantify agreement in results presented in those abstracts with their corresponding full-length publications.We screened abstracts of five WCPs held from 2008 to 2016 to find abstracts describing SRs. Two authors searched for corresponding full publications using PubMed and Google Scholar in April 2018. Methods and outcomes extracted from abstracts were compared with their corresponding full publications. The reporting quality of abstracts was evaluated against the PRISMA for Abstracts (PRISMA-A) checklist.We identified 143 conference abstracts describing SRs. Of these, 90 (63%) were published as full-length articles in peer-reviewed journals by April 2018, with a median time from conference presentation to publication of 5 months (interquartile range: -0.25 to 14 months). Among 79 abstract-publication pairs evaluable for discordance, there was some form of discordance in 40% of pairs. Qualitative discordance (different direction of the effect) was found in 13 analyzed pairs (16%). The median adherence by abstracts to each PRISMA-A checklist item was 33% (interquartile range: 29% to 42%).Conference abstracts of pain SRs are selectively published, not reliable, and poorly reported.