Abstract
Introduction: Respiratory function is a critical predictor of survival in amyotrophic lateral sclerosis (ALS). We aimed to determine if slow vital capacity (SVC) is a predictor of functional loss in ALS as compared to forced vital capacity (FVC).Methods: Consecutive ALS patients in whom respiratory tests were performed at baseline and 6 months later were included. All patients were evaluated with revised ALS functional rating scale (ALSFRS-R) and the respiratory tests, SVC, and FVC. Significant independent variables of functional decay were assessed by univariate Kaplan-Meier log-rank test and multivariate Cox proportional hazards model. A monthly decay not exceeding 0.92 in ALSFRS was considered as the time event.Results: We included 232 patients (134 men; mean onset-age 59.1 ± 11.23 years; mean disease duration from first symptoms to first visit: 14.5 ± 12.9 months; 166 spinal and 66 bulbar onset). All variables studied declined significantly between the two evaluations (p < 0.001). FVC and SVC were strongly correlated at study entry (r2 = 0.98, p < 0.001) and FVC and SVC decays between first evaluation and 6 months after were the only significant prognostic variables of functional decay (p < 0.001).Conclusion: FVC and SVC decay are inter-changeable in predicting functional decay in ALS. Pharmacological interventions reducing the decline rate of FVC and SVC can have a positive impact on the global functional impairment, with relevant implications for clinical trials' design and interpretation.
Highlights
Respiratory function is a critical predictor of survival in amyotrophic lateral sclerosis (ALS)
In a recent study [19], we found that slow vital capacity (SVC) and forced vital capacity (FVC) are very strongly correlated and decline in ALS, verified for patients with bulbar-onset and those presenting respiratory involvement
Both tests are strongly correlated with other respiratory tests namely maximal inspiratory (MIP) and maximal expiratory (MEP) pressures, and moderately correlated with clinical scores, this correlation is weaker for bulbar-onset patients [19]
Summary
Respiratory function is a critical predictor of survival in amyotrophic lateral sclerosis (ALS). ALSFRS-R comprises 12 questions with a maximal score of 48, corresponding to normal functionality in the three evaluated domains—bulbar, spinal, respiration This scale is applied worldwide in the ALS Units and used in clinical trials. FVC has been extensively studied in ALS and predicts hypoventilation and survival [8, 11,12,13,14,15,16], the reason why its values are determinant to patients’ eligibility for clinical trials It predicts functional decline as measured by the Appel ALS scale [11]. In a recent study [19], we found that SVC and FVC are very strongly correlated and decline in ALS (about 2%/month), verified for patients with bulbar-onset and those presenting respiratory involvement. In a second study [20], we verified that both FVC and SVC are independent predictors of survival, with a 1.05 increased probability of death for each 1% decay in their percentage of predicted value
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
