Ethics approval and consent to participate
AECOPD
The study was conducted in accordance with the Declaration of Helsinki. Included patients in this study were identified from a prospective pilot randomized controlled trial (IPRAC) that aimed to determine feasibility of monthly intravenous immunoglobulin infusions for one year to prevent recurrent AECOPD in hospitalized patients with AECOPD from Sep 2016 to Mar 2018 [