Insomnia complaints in lean obstructive sleep apnea patients negatively affect positive airway pressure treatment adherence

The objective of this study was to evaluate the determinants of long-term adherence to positive airway pressure (PAP) treatment among obstructive sleep apnea (OSA) patients with special emphasis on patients who stop PAP treatment within one year. This is a prospective long-term follow-up of subjects in the Icelandic Sleep Apnea Cohort (ISAC) who were diagnosed with OSA between the years 2005-2009 and started on PAP treatment. In October 2014, PAP adherence was obtained by systematically evaluating available clinical files (n=796; 644 males, 152 females) with moderate to severe OSA (apnea-hypopnea index ≥15 events/hr). The mean follow-up time was 6.7±1.2 years. In total, 123 subjects (15.5%) returned their PAP device within the first year, 170 (21.4%) returned it later and 503 (63.2%) were still using PAP. The quitters within the first year had lower body mass index (BMI), milder OSA, less sleepiness and more often had symptoms of initial and late insomnia compared to long-term PAP users at baseline. Both initial and late insomnia were after adjustment still significantly associated with being an early quitter among subjects with BMI < 30 kg/m 2 but not among those with BMI ≥ 30 kg/m 2 . The prevalence of early quitters decreased significantly during the study period (2005-2009). Almost two-thirds of moderate to severe OSA patients are PAP users after 7 years. Obesity level, OSA severity and daytime sleepiness are important determinants of long-term adherence. Symptoms of initial and late insomnia are associated with early quitting on PAP among non-obese subjects.