Forced vital capacity (FVC) as an indicator of survival and disease progression in an ALS clinic population

In a large cohort of 1034 patients with the diagnosis of definite or probable amyotrophic lateral sclerosis (ALS), the association of forced vital capacity (FVC) at baseline with (a) time to progression of 20 points in Appel ALS (AALS) score or (b) tracheostomy free survival was investigated. The median survival of ALS patients with baseline FVC <75% was 2.91 years, compared with 4.08 years for patients with baseline FVC >75% (p<0.001). Patients with baseline FVC <75% progressed more rapidly (taking 8.0 months to progress 20 AALS points) compared with patients with baseline FVC >75% (10.0 months, p<0.001). Moreover, FVC at first examination was identified as a significant predictor of survival and disease progression in both univariate and multivariate Cox regression models, after adjustment for age, sex, site of onset, diagnostic delay, riluzole therapy, and use of bilateral positive airway pressure and percutaneous endoscopic gastrostomy (p<0.001). We conclude that a single FVC value obtained at an initial visit may serve as a clinically meaningful predictor of survival and disease progression in ALS.