Reliability of Home Spirometry Compared to Traditional Clinic Spirometry in an Adult Cystic Fibrosis Population

Abstract

RATIONALE: The potential risk of acquiring COVID-19 has presented a particular challenge to delivering in-person outpatient care, especially to patients with chronic respiratory diseases who may be hesitant to come to clinic. Though much of an interdisciplinary visit for cystic fibrosis can be performed via telehealth, in-clinic spirometry is an important part of disease monitoring. Home spirometry has been proposed as a way to improve telehealth in cystic fibrosis care. Here we examine the reliability of home spirometers in an adult cystic fibrosis clinic. METHODS: Patients received home spirometers (Mir Spirobank Smart, n = 38) from the Cystic Fibrosis Foundation or obtained their own Microlife home spirometers (n = 2). They were instructed to bring their home spirometer to clinic for teaching and comparison with the calibrated clinical spirometer. Initial patient demographics, exacerbations in the last year, current symptoms, home airway clearance and inhaler regimen were recorded. After the initial visit, patients were emailed links to report symptoms and record home spirometry weekly or with worsening of their symptoms. Data was recorded in REDCap and analyzed in RStudio version 1.3.1056. RESULTS: A total of 40 patients have completed the initial clinic visit and teaching for their home spirometers. The clinic and home spirometers were very highly correlated when measuring forced expiratory volume in one second (FEV1) with a Pearson correlation coefficient 0.993 (P < 0.001) with the clinic spirometer recording a higher value, on average, of 0.072 ± 0.11 L (mean ± standard deviation). Of the 36 patients that had a home spirometer forced vital capacity (FVC) recorded, the correlation coefficient was 0.946 (P < 0.001) with the clinic spirometer recording a higher value of 0.134 ± 0.31 L on average. Measurements of percent predicted of FEV1 and FVC had Pearson correlation coefficients of 0.987 (P<0.001) and 0.953 (P<0.001), respectively, with clinic spirometers showing higher values, on average, of 0.806 ± 3.54 % and 1.31 ± 1.12 %, respectively. Peak expiratory flow (L/s), on the contrary, tended to be higher on the home devices by 0.542 ± 1.12 L/s on average, with a Pearson correlation coefficient of 0.857 between devices. Home spirometry measurements are ongoing. CONCLUSIONS: Home spirometry provide similar estimates of lung function compared to standard in-clinic devices and could play a useful role in the longitudinal telehealth care of cystic fibrosis patients. The reliability of their measurements in the home environment is currently ongoing.