Sugiyama A, Shiota S, Yanagihara M, et al. - Researchers investigated the influence of long-term treatment on the alteration in pathogenesis and natural progression of obstructive sleep apnea (OSA). Polysomnography was conducted twice with a median (range) follow-up of 93 (60–176) months, in all 154 consecutive OSA patients managed by continuous positive airway pressure (CPAP) using an auto-titrating continuous positive airway pressure device (CPAP-APAP) (n = 112), or by oral appliance (OA) (n = 27) or were untreated (n = 15). In multivariate logistic regression, BMI decrease and good treatment adherence were revealed as significant predictors of favourable OSA progression, as represented by an improved or unaltered apnea–hypopnea index. Findings revealed that determinants in the natural progression of OSA severity included: weight as well as treatment adherence.