The Long-Term Uptake of Home Spirometry in Regular Cystic Fibrosis Care: Retrospective Multicenter Observational Study - Pia Bertram; Martinus C Oppelaar; Michiel AGE Bannier; Monique HE Reijers; Hester van der Vaart; Renske van der Meer; Josje Altenburg; Lennart Conemans; Bart L Rottier; Marianne Nuijsink; Lara S van den Wijngaart; Peter JFM Merkus; et al. (Journal of Medical Internet Research)