Feasibility and Acceptability of Home Spirometry in the Adolescent Cystic Fibrosis Population

Abstract

Rationale Cystic Fibrosis (CF) patients are at-risk for loss of lung function. Although current guidelines recommend in-person clinical care quarterly, the COVID-19 pandemic has necessitated fundamental changes in patient monitoring. This study characterizes the acceptance, consistency and reproducibility of home-based spirometry in a CF adolescent population. Methods Adolescents with CF were trained on home spirometry inperson or remotely using video technology by a dedicated CF respiratory therapist (RT). After initial training, patients were instructed to send results weekly to the RT. After reliable technique was established, patients were instructed to send results monthly. FEV1 from home and the closest in-office spirometry were compared for accuracy within <10% variance. Additional FEV1 values were trended over time for consistency, defined as a <10% change from the mean in-home spirometry results. The Cystic Fibrosis Questionnaire-Revised (CFQ-R) was administered to correlate with spirometry values by phone or in-clinic. Results Home spirometers (Zephyrx® Albany, NY) were supplied by the CF Foundation to forty adolescents with CF (Mean age= 15.4yr, 50% female, 85% Caucasian, 85% on CFTR-modulator therapy) over 6 months from May-November 2020. As of December 2020, 34 patients (85%) completed initial training on the device. Of these, 28 reported results (82%, mean FEV1=2.55L) and 6 did not (18%). Of these 28, 15 are still establishing reliable technique with weekly reporting. 12 have established reliable technique and moved to monthly reporting. When home spirometry FEV1 values were compared to in-clinic FEV1 values at the closest time point, 78% (22/28) were accurate (defined as difference <10%). The 12 patients who attained competency for monthly reporting have mean age=16yr, 75% female, 83% Caucasian, 91% on CFTR-modulator therapy. FEV1 values in this group have demonstrated consistency in results and technique over time. The mean home spirometry FEV1 in this cohort is 2.56L. These patients returned an average of 8 results/patient (range 4-12). 11/12 (91%) of these patients showed consistency, defined as a <10% variance from the mean in-home spirometry value. No patient performing home spirometry has had a pulmonary exacerbation. Although CFQ-R was provided to all 34 trained patients, only 8 completed this questionnaire. Conclusion Home spirometry is an accurate, consistent and feasible tool to monitor the pediatric CF population remotely. A dedicated RT for training and patient follow-up is a critical factor for successful implementation. We attempted to correlate the CFQ-R with home spirometry, but patients were less likely to return the questionnaire.