Two-year CPAP adherence in obstructive sleep apnea patients in Vietnam: the first prospective cohort

Long-term adherence to continuous positive airway pressure (CPAP) therapy in obstructive sleep apnea (OSA) often falls below 30 %. We report the first two-year evaluation of CPAP adherence among Vietnamese patients with moderate to severe OSA. In this prospective cohort, 32 treatment-naïve adults (Apnea–hypopnea index -AHI ≥ 15 events/h) were enrolled following in-lab polysomnography. Adherence was defined as ≥ 4 h/night on ≥ 70 % of nights over any 30-day period. CPAP monitoring and usage parameters (apnea-hypopnea index - residual AHI, compliance, adherence, P95 pressure- Mean 95th percentile CPAP pressure, air leakage) were recorded at 1, 3, 6, 9, 12, and 24 months. Predictors of long-term adherence were analyzed using correlation models. All 32 participants completed follow-up. Adherence rates were 65.6 % at 1 month, 53.1 % at 3 months, 46.9 % at 6, 9, and 12 months, and 50.0 % at 24 months. Mean AHI fell from 56.3 ± 18.2 to 2.9 ± 2.8 events/h after one month ( p < 0.001) and remained stable. Higher baseline AHI, obstructive apnea index, and apnea duration, lower mean SpO₂, and good 3-month adherence were all significantly associated with sustained use at two years. Approximately half of Vietnamese patients with moderate to severe OSA remain adherent to CPAP after two years. Both initial disease severity and early treatment adherence independently predict long-term adherence, underscoring the importance of close monitoring and intervention during the first three months of therapy.