We measured erect seated FVC [eFVC] and supine FVC [sFVC] using in-clinic-conventional [Viaire and Vyasis, USA], in-clinic-portable and at-home-portable [MIR Spirobank Smart, Italy] spirometers with in-person and internet-based respiratory therapist coaching.
We adapted baseline eFVC in an algorithm to facilitate prognostication of individual patients and customize management strategies as described for lung transplantation patients [Mohanka 2000] and ALS [Elamin 2018, Torrieri 2022].Classification of disease progression based on stratified forced vital capacity is a model used to identify clinical phenotypes in ALS [Ackrivo 2019]. Remote monitoring of FVC using internet-based system is a validated method in primary pulmonary disorders, but not in ALS.
Electronic health records of 22/95 ALS clinic patients (23%) from single ALS center that launched AHT between July 2020 to June 2021 was reviewed in this IRB-approved retrospective study. Patients were stratified according to baseline eFVC >=80 %, 60%-80%, <=60% predicted.
eFVC acquired within a 7-day period (N=16) were highly correlated in liters [R2=0.926; p<0.0001] and %p [R2=0.922, p < 0.001]. Bland-Altman analysis showed a mean difference of 0.15L [conventional – portable]; 95% limits of agreement =-0.40L to 0.70L; 2.7 %p [-12.1% to 17.5%].
eFVC < 60 %p at baseline entry had statistically significant [ < 60 %p mean = 766 days, 95%CI= 368 to 1162 days; > 60 %p mean = 2638 days, 95%CI = 1479 to 3797 days; HR = 0.2218 95% CI = 0.07614 to 0.8008; P = 0.0215] decreased survival compared with the upper tertiles combined.We are conducting a larger prospective confirmatory study [NCT05106569] to validate AHT measurement of SVC [slow vital capacity] to determine if a higher level of peak lung functions at ALS diagnosis would be associated with longer survival and better outcomes in relation to overall respiratory care management.