Slow vital capacity as a useful indicator of the prognosis after percutaneous endoscopic gastrostomy in patients with amyotrophic lateral sclerosis.

Objectives: Forced vital capacity (FVC) is recommended as a respiratory function test in patients with amyotrophic lateral sclerosis (ALS). However, in ALS associated with orofacial palsy, FVC may be an unreliable test. Slow vital capacity (SVC) is an easier and more reliable test even in cases with bulbar symptoms. However, it remains unclear whether respiratory function tests using SVC and FVC are associated with prognosis after percutaneous endoscopic gastrostomy (PEG) placement. This study aimed to confirm whether both SVC and FVC are related to prognosis after PEG placement in patients with ALS.

Materials And Methods: We conducted this retrospective observational cohort study of 69 consecutive patients diagnosed with sporadic ALS who underwent PEG placement between July 2007 and February 2020. We analyzed the association with mortality 6 months after PEG placement and evaluated long-term prognosis.

Results: Forty-four patients met the inclusion criteria. In cases with decreased SVC (p < .01) and FVC (p < .01), a significant difference was observed in mortality 6 months after PEG placement, with an optimal cut-off of SVC ≤57.4% (sensitivity, 0.828; specificity, 0.867) and FVC ≤57.3% (sensitivity, 0.828; specificity, 0.867). Multivariate analysis showed that onset age ≥ 65 years (p < .05), SVC ≤57.4% (p < .01), and FVC ≤57.3% (p < .01) were associated with survival after PEG placement.

Conclusions: SVC, like FVC, is an important prognostic factor after PEG placement in patients with ALS, and there is a possibility that evaluation using SVC can complement respiratory function testing even in cases where the evaluation of FVC is limited.