MMP9 and obstructive sleep apnea syndrome: Despite uninterrupted CPAP therapy, at the 5-year control visit increased levels of MMP-8, MMP-9 and TIMP-4 were detected compared to those at the time of OSA diagnosis (578 (255–1167 [95% CI 295–1070]) vs. 287 (170–560 [95% CI 226–403]) pg/mL at baseline, p = 0.017; 15.0 (12.4–24.2 [95% CI 12.9–22.7]) vs. 12.7 (10.4–15.6 [95% CI 10.8–15.0]) ng/mL at baseline, p = 0.014 and 893 (496–1542 [95% CI 568–1428]) vs. 828 (387–1211 [95% CI 482–1074]) pg/mL at baseline, p = 0.023, respectively; Fig. 2).