Critical appraisal (I): Fundamentals, tools, and application to scientific articles on outcomes and harmful effects Javier González de Dios; María Salomé Albi Rodríguez; Álvaro Gimeno Díaz de Atauri; Laura Cabrera Morente; Elena Pérez González; Carlos Ochoa Sangrador;

Pediatric virtual visits: experiences, preferences, and expectations of patients and caregivers Miren Ibarzabal Arregi; Tregony Simoneau; Jonathan M. Gaffin; María Gimeno Castillo; Isabel Castro Garrido; Claudia María Chaverri Reparaz; Laura Moreno-Galarraga;

Frequency, risk and impact measures in epidemiology Carlos Ochoa Sangrador; Eduardo Ortega Páez; Manuel Molina Arias; Fernando Carvajal Encina; Eduardo Cuestas Montañes;