Theme 10 - Disease Stratification and Phenotyping of Patients

Background: COVID-19 pandemic presents new opportunities to augment respiratory monitoring complementary to remote telehealth services. Stratification of vital capacity may allow for characterization of FVC and disease trajectory clusters (1). Objective(s): In this implementation science study, we assessed the feasibility of measuring FVC in seated upright and supine positions obtained with in-clinic-conventional (Viaire and Vyasis, USA), in-clinic-portable and at-home-portable (MIR Spirobank Smart, Italy) spirometers with respiratory therapist coaching. Method(s): Electronic health records of 22/95 ALS clinic patients (23%) from single-center in Central New York that launched AHT between July 2020 and June 2021 was reviewed in this IRB-approved retrospective study. Mean age of patients was 65 years old and 9 were males. Patients were stratified according to baseline seated FVC % predicted by conventional method: Group A, FVC >80%, Group B, 60-80%, Group C <60% predicted. Patients unable to come to clinic received spirometers by mail followed with remote training with respiratory therapists without conventional spirometry. Result(s): Pearson correlation coefficient was used to evaluate the correlation between FVC measurement using conventional and portable spirometry by position. Bland-Altman analysis was performed to evaluate the mean difference (conventional - portable) with 95% limits of agreement. Measurement of seated FVC acquired during the same clinic visit (N=13) were highly correlated in liters (R2=0.95, p<0.0001) and % predicted (R2=0.952, p<0.0001). Bland- Altman analysis showed good agreement with a mean difference of 0.147L, 0.345 to 0.639L);4.154% predicted, (8.004 to 16.311%). In-clinic supine FVC (N=4) were highly correlated in liters (R2=0.987, p=0.007) and % predicted (R2=0.987, p=0.007) with a mean difference of =0.33L, (0.101 to 0.761L);8.5% predicted, (0.043-17.043%). Supine vital capacity measurements were more frequently obtained with AHT 35/52 (67.31%) vs. 9/21(42.86%) with Conventional spirometry. Safety concerns associated with patient transfers were the most frequently encountered barrier in performing supine testing in clinic. Reason for drop out for 2/22 patients with no remote AHT was attributed to perceived aggravation of anxiety from readily viewing FVC results on smartphone and low baseline FVC (<50% predicted). AHT led to prompt initiation of NIV in 5/22 patients, of which 3 were homebound, had low FVC at initial AHT (12-48% predicted), low ALS FRSR (14-28 out of 48) and received remote AHT training without conventional spirometry. An ongoing slow vital capacity (NCT05106569) prospective clinical study in ALS will determine if frequent respiratory surveillance from home using AHT leads to better outcomes in relation to use of NIV.