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

BACKGROUND: 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. OBJECTIVE: We assessed NIV adherence during the first year of outpatient adaptation, factors associated with time-dependent adherence, and the relationship between adherence and survival. METHODS: 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. RESULTS: 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). CONCLUSION: 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.