Original article Gender differences on polysomnographic findings in Greek subjects with obstructive sleep apnea syndrome E. Vagiakis a , F. Kapsimalis b, * , I. Lagogianni a , H. Perraki a , A. Minaritzoglou a , K. Alexandropoulou a , C. Roussos a , M. Kryger c a Critical Care and Pulmonary Services, Medical School, Sleep Disorders Center, Evangelismos Hospital, University of Athens, Athens, Greece b Sleep Laboratory, Respiratory Medicine Department, Henry Dunant Hospital, 107 Mesogeion Avenue, GR 115 26 Athens, Greece c Sleep Disorders Centre, St Boniface Hospital Research Center, University of Manitoba, Winnipeg, Man., Canada Received 3 August 2005; received in revised form 27 December 2005; accepted 30 December 2005 Available online 5 June 2006 Abstract Background and purpose: Studies from North American clinics have reported that females with obstructive sleep apnea syndrome (OSAS) are about the same age as males but are heavier, have less severe apnea and make up a much smaller proportion of cases. We examined polysomnographic differences between Greek men and women with OSAS in order to study the influence of gender on clinical presentation and laboratory findings. Patients and methods: This retrospective study included a cohort of 1010 Greek patients (844 males, 166 females) diagnosed with OSAS by overnight polysomnography (PSG), who were referred to the Sleep Disorders Center of Evangelismos Hospital, Athens Medical School, University of Athens. All patients were studied over a period of three consecutive years, during which time clinical and polysomnography (PSG) findings were compared. Results: Body mass index (BMI) was similar in men and women with OSAS (BMIZ31.6G5.5 kg/m 2 in men versus BMIZ32.5G8.1 (SD) kg/m 2 in women). Female patients were significantly older than male patients (56.9G10.6 versus 50.6G11.7 year, PZ0.001). The mean apnea–hypopnea index (AHI) during total sleep time was higher in men than in women (42.4G28.2 versus 33.2G27.7 events/h, P!0.001). The AHI in non-rapid eye movement (NREM) sleep was higher in men than in women (42.9G28.9 versus 32.6G28.7 events/h, P!0.001), but in rapid eye movement (REM) sleep AHI was similar in men and women (36.0G23.3 versus 34.9G25.4 events/h). Forty percent of men had AHI–REM sleep OAHI–NREM compared to 62% of women, and the difference between REM and NREM–AHI was significantly less in men than in women (14.21G11.18 versus 19.76G13.43 events/h, P!0.001)). Several aspects of sleep were worse in women versus men: sleep efficiency index was lower (79.4G16.1% versus 85.1G12.5%, P!0.001); sleep onset latency (27.7G27.7 versus 17.9G18.1 min, P! 0.001), and REM onset latency (161.5G76.2 versus 145.7G71.4 min, P!0.018) were longer; wake time after sleep onset (WASO) was also greater in women (42.6G46.5 versus 30.7G34.9 min, P!0.003). Conclusions: In Greek subjects with OSAS, there was no difference in BMI, and female patients were significantly older than male patients. OSAS was diagnosed in men five times more often than in women. AHI was greater in men than in women, but women are more likely than men to have a higher AHI in REM than NREM. Sleep quality is worse in female than in male patients. q 2006 Elsevier B.V. All rights reserved. Keywords: Sleep apnea; Polysomnography; Sex; Gender; Sleep 1. Introduction Obstructive sleep apnea syndrome (OSAS) is characterized by repeated episodes of upper airway obstruction during sleep, resulting in oxyhaemoglobin desaturation and sleep fragmen- tation. OSAS is defined by an apnea–hypopnea index (AHI) O5 with daytime symptoms such as excessive sleepiness [1]. Early epidemiological studies of this disorder included only men because the first clinical reports suggested that OSAS is primarily a male disorder. In clinics, a male:female ratio for OSAS of 10:1 or even greater was reported [2,3]. Community- based epidemiological studies have reported a male:female prevalence ratio of about 2:1–4:1 [4,5], while clinic-based studies report a male:female ratio of about 4:1–6:1 [6,7]. Sleep Medicine 7 (2006) 424–430 www.elsevier.com/locate/sleep 1389-9457/$ - see front matter q 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2005.12.014 * Corresponding author. Tel.: C30 210 6972000; fax: C30 210 6972869. E-mail address: fogeka@otenet.gr (F. Kapsimalis).