Knowledge user involvement is still uncommon in published rapid reviews—a meta-research cross-sectional study. - Nussbaumer-Streit, Barbara; Ledinger, Dominic; Kien, Christina; Klerings, Irma; Persad, Emma; Chapman, Andrea; Nowak, Claus; Gadinger, Arianna; Affengruber, Lisa; Smith, Maureen; Gartlehner, Gerald; Griebler, Ursula (Research Synthesis Methods, 2025)