Original Article The effect of gender on the prevalence of hypertension in obstructive sleep apnea Vahid Mohsenin a, * , H. Klar Yaggi a , Neomi Shah a , James Dziura b a Yale Center for Sleep Medicine, Yale University School of Medicine, 40 Temple Street, New Haven, CT 06510, USA b Yale Center for Clinical Investigation, Yale University School of Medicine, New Haven, CT 06519, USA article info Article history: Received 25 February 2008 Received in revised form 20 August 2008 Accepted 21 September 2008 Available online 29 January 2009 Keywords: Cardiovascular Obesity Sleep apnea Hypertension Sex abstract Background: Obstructive sleep apnea (OSA) causes systemic hypertension. However, there is conflicting data on the effect of gender on susceptibility to hypertension in OSA. Some show no gender differences in the prevalence of hypertension while others report either female or male propensity to have hyperten- sion in the context of OSA. The inconsistencies in the results appear to be due to lack of full range of sleep apnea severity and insufficient number of women in the studies. We examined the effect of gender on prevalent hypertension in a cohort with a large representation of females with OSA. Methods: A cross-sectional study of a large cohort of subjects referred for sleep disorder evaluation. Results: The cohort comprised of 736 with OSA and 315 without OSA. OSA was defined as apnea-hypo- pnea index (AHI) of P5/h. There were 529 men and 207 women in the OSA group with mean ± SD age of 50 ± 13 and 51 ± 14 years, respectively. The control group consisted of 154 men and 161 women with mean ± SD age of 44 ± 15 and 43 ± 14 years, respectively. The AHI in the OSA group varied from 5 to 197 with a median of 24 and a mean of 36 (interquartile range: 11–53). Multiple logistic regression anal- yses, modeling the association between AHI and hypertension and considering other covariates, showed that odds of hypertension increased with increasing age, BMI, and AHI. There was evidence that men were at higher risk for hypertension than women OR 1.82 (95%CI 1.01, 3.20) at the highest quartile of BMI. Conclusions: We have shown that the prevalence of hypertension increases with increasing age and severity of OSA, and markedly obese men may have a nearly 2-fold greater risk for hypertension than women in this clinic-based population. Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction Obstructive sleep apnea (OSA) is characterized by recurrent upper airway obstruction during sleep. These episodes are termi- nated by arousals and are commonly associated with oxygen desaturation. OSA syndrome is a highly prevalent disorder with an estimated prevalence of 4% and 2% in middle-aged adult men and women, respectively [1,2]. A growing body of evidence shows that OSA syndrome is independently associated with sig- nificant cardiovascular morbidity and mortality, including coro- nary artery disease, heart failure and stroke [3–6]. The acute hemodynamic and autonomic perturbations that accompany obstructive apneas during sleep, associated with repeated arous- als and intermittent hypoxemia, can lead to sustained diurnal hypertension, independent of other known risk factors for hyper- tension [7,8]. The prevalence of hypertension in OSA ranges be- tween 30% and 70% [9]. Epidemiological studies [7,10], clinic- based studies [11,12], and case-control studies [13] have consis- tently shown that the risk for hypertension increases with increasing severity of OSA even after correction for several fre- quently encountered comorbid conditions such as obesity and age. However, the effect of gender on the development of hyper- tension in OSA has not been entirely elucidated. Population- based studies showed no consistent evidence for gender differ- ences in the prevalence of hypertension in adults with sleep-dis- ordered breathing [7,10,14]. Some show no association with gender [7,10], while another population-based study demon- strated that men were more prone to hypertension than women with OSA [14]. Other studies drawing from a clinic population have shown that females are more prone to endothelial dysfunc- tion [15] and hypertension [16] than males with OSA. The incon- sistencies appear to be related to a limited range of severity of OSA and few female subjects in the cohorts. We undertook this study to address the gaps and inconsisten- cies in the role of gender susceptibility to hypertension in OSA. In this study, we describe the effect of gender on the prevalence of hypertension in a cohort of sleep clinic patients with a wide 1389-9457/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2008.09.005 Abbreviations: OSA, obstructive sleep apnea; BMI, body mass index; AHI, apnea– hypopnea index. * Corresponding author. Tel.: +1 203 562 9901; fax: +1 203 624 4950. E-mail address: vahid.mohsenin@yale.edu (V. Mohsenin). Sleep Medicine 10 (2009) 759–762 Contents lists available at ScienceDirect Sleep Medicine journal homepage: www.elsevier.com/locate/sleep