Tailoring patients' enrollment in ALS clinical trials: the effect of disease duration and vital capacity cutoffs.

To evaluate how Amyotrophic Lateral Sclerosis (ALS) patients' mortality rates change, based on different levels of forced vital capacity (FVC) and disease duration, providing a scheme of mortality rates of a real population of ALS patients to improve the design of future RCTs. : One random spirometry for each ALS patient was selected during four time intervals from disease onset: (1) ≤12 months; (2) ≤18 months; (3) ≤24 months; (4) ≤36 months. Date of spirometry corresponded to date of trial entry, while time interval onset-spirometry to disease duration at enrollment.