Effects of continuous positive airway pressure on periodic limb movements during sleep in patients with obstructive sleep apnea

Objective To investigate the effects of continuous positive airway pressure (CPAP) on periodic limb movements during sleep (PLMS) in patients with obstructive sleep apnea (OSA). Methods The polysomnography (PSG) data of 828 consecutive OSA outpatients from January 2015 to January 2017 who had undergone overnight CPAP titration were analyzed retrospectively. On the basis of changes in periodic limb movements index (PLMI) values (cut off level≥15/h) from baseline PSG (BPSG) to CPAP titration PSG, patients were assigned to one of the following four groups: persistent, CPAP-emergent, CPAP-disappeared, and non-PLMS. Results Among 828 patients, 756 (91.3%) were male and 72 (8.7%) were female. The mean age was (45.7±10.7) years old, the mean body mass index (BMI) was (27.6±3.5) kg/m2. The rate of patients was 3.9% in the persistent group, 10.3% in the CPAP-emergent group, 7.5% in the CPAP-disappearance group, and 78.4% in the non-PLMS group. Multivariate Logistic regression analysis revealed that female appeared to be associated with the persistent group (P=0.004); older age and higher apnea-hypopnea index (AHI) on BPSG appeared to be associated with the CPAP-emergent group (P=0.012, 0.030). On the other hand, older age was negatively associated with the non-PLMS group (P=0.006). Conclusion Elderly patients with higher AHI at BPSG may present with CPAP-emergent PLMS. Key words: Sleep apnea, obstructive; Continuous positive airway pressure; Periodic limb movements during sleep