Time-dependent adherence to non-invasive ventilation in amyotrophic lateral sclerosis: an observational cohort study

Non-invasive ventilation (NIV) improves survival and quality of life in amyotrophic lateral sclerosis (ALS). However, adherence is frequently suboptimal and longitudinal outpatient data are limited.

We assessed NIV adherence during the first year of outpatient adaptation, factors associated with time-dependent adherence, and the relationship between adherence and survival.

We conducted a retrospective cohort study including individuals with ALS prescribed with NIV between January 2022 and June 2024 at the outpatient clinic of an Italian referral centre. Functional status, adherence, and device-related complications were recorded at 1, 3, 6, and 12 months. Data about deaths and tracheostomy events were collected.

Complete adherence data were available for 73 patients. Mean NIV use increased; nevertheless, approximately 30% of patients were non-adherent at 6 and 12 months. NIV-related complications ranged between 30-44%, though they were not significantly associated with adherence. Higher ALSFRS-R respiratory subscore (OR=0.78, 95% CI 0.64-0.95) and having a male caregiver (OR=0.19, 95% CI 0.04-0.96) were associated with reduced adherence. Time-dependent adherence was not significantly associated with survival, whereas older age at diagnosis and PEG placement were associated with a 5% and more than threefold higher risk of death/tracheostomy, respectively (HR 1.05, 95% CI 1.01-1.09; HR 3.42, 95% CI 1.54-7.59).

NIV adherence and NIV-related complications showed dynamic patterns over time. One-third of patients were non-adherent at 6 and 12 months, highlighting the need for tailored interventions throughout follow-up. Although time-dependent adherence was not independently associated with survival, period-averaged adherence appeared to produce a more favourable survival estimate than time-dependent adherence.