Peak expiratory flow is a reliably household pulmonary function parameter correlates with disease severity and survival of patients with amyotrophic lateral sclerosis

Background Amyotrophic lateral sclerosis (ALS) is an incurable and fatal neurodegenerative disease; most ALS patients die within 3 to 5 years after symptom onset, usually as a consequence of respiratory failure.

In the present study, we aim to screen the survival-related pulmonary function parameters, and to explore the predictive value of peak expiratory flow (PEF) in disease severity and prognosis in patients with ALS.

Methods The discovery cohort included 202 ALS patients, and the demographic and clinical characteristics of eligible patients were collected and pulmonary function tests were performed using MS-PFT spirometer.

In the validation cohort, 62 newly diagnosed ALS patients performed the pulmonary function test by MS-PFT spirometer and household peak flow meter (KOKA) simultaneously.

Results Among 12 pulmonary function parameters, FVC, FEV1, PEF, MEF75%, and MVV were identified to be independent predictive factors for survival.

PEF was highly correlated with FVC ( r  = 0.797), MVV ( r  = 0.877), FEV1 ( r  = 0.847), and MEF75% ( r  = 0.963).

Besides, the values of PEF were positively associated with disease severity (ALSFRS-R score, r_s = 0.539, P  < 0.0001), and negatively associated with progression rate (ΔALSFRS-R, r_s = -0.316, P  < 0.0001).

Finally, we also confirmed that the values of KOKA-measured PEF were highly correlated with the ones measured using MS-PFT spirometer ( r  = 0.9644, p  < 0.0001).

Conclusions Our work emphasizes the critical role of PFTs in predicting prognosis of ALS patients.

PEF is an easily available pulmonary function index, which is also a promising indicator in predicting disease severity and survival for ALS patients.