Healthcare (Basel) Healthcare (Basel) Application of the Delphi method for content validity analysis of a questionnaire to determine the risk factors of the Chemsex del Pozo-Herce Pablo Martínez-Sabater Antonio Chover-Sierra Elena Gea-Caballero Vicente Satústegui-Dordá Pedro José Universidad de Zaragoza Saus-Ortega Carles Tejada-Garrido Clara Isabel Sánchez-Barba Mercedes Pérez Jesús Juárez-Vela Raúl Santolalla-Arnedo Iván Baca-García Enrique 2023 research-article