Different scoring rules for respiratory event-related leg movements: effects on the prevalence of periodic limb movements during sleep and their association with depressive symptoms in patients with obstructive sleep apnea.

Background: We compared the prevalence of periodic leg movements during sleep (PLMS) according to two different scoring rules of the American Academy of Sleep Medicine (AASM) 2012 and World Association of Sleep Medicine (WASM) 2016 and determined their association with depressed mood in patients with obstructive sleep apnea (OSA).

Methods: PLMS, defined as a periodic leg movements index of >15, were diagnosed on a diagnostic and continuous positive airway pressure (CPAP) titration polysomnography using the AASM 2012 and WASM 2016 rules. The Beck Depression Inventory (BDI) and Epworth Sleepiness Scale (ESS) were used, and multiple regression analyses were performed.

Results: Among 160 OSA patients, the proportion with PLMS scored by the WASM 2016 criteria was significantly higher than that scored by the AASM 2012 criteria in a diagnostic study (20.6% vs. 16.3%, respectively; P = 0.016) but not in CPAP titration study and only in patients with severe OSA. In adjusted models, PLMS were positively associated with BDI scores and a BDI of ≥10 on both diagnostic and CPAP titration studies when scored by the WASM 2016. By contrast, when scored by the AASM 2012, PLMS were associated with BDI scores (but not BDI of ≥10) only in a CPAP titration study.

Conclusions: There are significant differences in the prevalence of PLMS and their association with depressed mood depending on the scoring rules in patients with OSA. The current AASM scoring criteria underestimate the prevalence of PLMS, and PLMS are more likely associated with depressed mood according to the WASM scoring criteria.