The Validation of Actigraphy for Detection of Periodic Leg Movement in Obstructive Sleep Apnea

Address for correspondence Sang-Ahm Lee, MD Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, 86 Asanbeongwon-gil, Songpa-gu, Seoul 138-736, Korea Tel: +82-2-3010-3445 Fax: +82-2-474-4691 E-mail: salee@amc.seoul.kr Objectives: Several validation studies of actigraphy for periodic limb movements (PLMs) detection reported a high sensitivity and specificity in restless leg syndrome and periodic limb movement disorder. But PLMs also arise in association with a variety of other sleep disorders such as the sleep apnea syndrome. We compared PLM counts obtained with polysomnography (PSG) to those obtained from actigraphy with PAM-RL and assess the validity in patients with obstructive sleep apnea. Methods: Sixty patients with obstructive sleep apnea underwent actigraphy from both legs and simultaneous PSG during awakeness and sleep. Each of left and right PLM indices by unilateral actigraphy were calculated automatically and compared to PLM index by PSG of ipsilateral leg. Additionally, a comparison among the severity of apnea-hypopnea index (AHI) in obstructive sleep disorder was performed. Results: PLM index obtained with actigraphy were not different from PLM index by PSG [7.93(±11.65)/h vs. 6.50(±12.45)/h; p=0.257]. The sensitivity and specificity of actigraphy identifying patients with PLM index ≥15/h against respective PLM index determined by PSG were calculated (sensitivity/specificity: 0.53/0.88). The actigraphy didn’t overestimate PLM in overall OSA, but overestimate only in severe OSA. Conclusions: This discrepancy between PSG and actigraphy in patient with OSA may be due to overestimate of actigraphy in severe OSA and to underestimate of PLM as PLM index increases. Actigraphy can’t replace PSG in the diagnostic assessment of PLM using cut-off values in patients with obstructive sleep apnea on account of this problem. J Korean Sleep Res Soc 2010;7:43-48