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In amyotrophic lateral sclerosis (ALS), non-invasive ventilation (NIV) improves survival; however, the phenotype of patients who are most likely to benefit remains unclear. This study aimed to identify predictors of survival at initiation of NIV. A retrospective review (September 2018 - June 2022) of patients with ALS initiated on NIV at a tertiary referral centre was conducted. Survival analysis was performed with a Cox regression model. 105 patients (56% male) with ALS (69% limb-onset, 31% bulbar-onset) received new NIV treatment. Age (mean±SD) at initiation was 66±11 yrs, BMI was 23±6 kg/m2. Daytime CO2 at initiation was 5.7±0.8 kPa, sniff nasal inspiratory pressure (SNIP) was 25±19 cmH2O, and peak cough flow (PCF) was 197±100 L/min. At 3-months following initiation, median (IQR) NIV adherence was 1.0 (0-5.5) hours per night. 28% were using NIV for more than four hours per night, while 43% used it for zero hours. Median survival (95%CI) from initiation of NIV was 354 (287;421) days. In those who used NIV more than four hours per night, median survival was 479 (237;721) days. Mortality at 6-month was 26%, at 12-months was 51% and 18-months was 70%. Increasing age (HR 1.03 1.01, 1.05, p=0.02), lower BMI (HR 0.95 0.91,0.98 p=0.004), lower PCF (HR 0.99 0.99,0.99 p<0.001) and lower adherence at first review (HR 0.93 0.87,0.99 p=0.049) were associated with reduced survival. ALS phenotype and SNIP were not associated with survival. In conclusion, potentially modifiable factors such as nutritional state, cough function and NIV adherence are associated with improved survival. It remains to be proven if interventions in these areas could improve outcomes.
Shah et al. (Thu,) studied this question.