==== Front Ann Saudi MedAnn Saudi MedAnnals of Saudi Medicine0256-49470975-4466King Faisal Specialist Hospital and Research Centre 10.5144/0256-4947.2008.225asm-3-225LettersPredictors of obstructive sleep apnea: special considerations for females BaHammam Ahmed Salem MDKing Saud University, College of Medicine, Riyadh, Saudi Arabia ashammam2@gmail.comMay-Jun 2008 28 3 225 226 Copyright © 2008, Annals of Saudi Medicine2008This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. ==== Body To the Editor: I read with interest the article by Ibrahim et al exploring the predictors of obstructive sleep apnea (OSA) in snorers.1 The authors reported no age difference between females with and without OSA. For females, including age without considering the menopausal status can be misleading. In females, the menopausal status is one of the most important risk factors and predictors of OSA and its assessment is an essential part of any study looking into OSA in females. Young et al assessed the association between the menopausal status and sleep-disordered breathing (SDB) in women.2 After adjusting for potential confounders like age, body mass index and smoking, the authors calculated the odds ratio (95% CI) for an apnea/hypopnea index (AHI) of more than five per hour of sleep to be 1.2 (0.7–2.02) in perimenopausal and 2.6 (1.4–4.8) in postmenopausal women.2 After menopause, the prevalence of OSA in women approaches that in men and reaches its peak in the fifth and sixth decades.2,3 In general, the prevalence of OSA peaks at around 55 years in men and at around 65 years in women.4 This can be related to postmenopausal status as the risk of SDB was shown to be at least 2.5 times higher in post-than in premenopausal women, 2 and it approximates that of men at the time of menopause.5 Female hormones (especially progesterone) may play a role in increasing upper airway muscle activity during wakefulness and non-rapid eye movement sleep.6 Furthermore, there are important gender differences in central ventilatory control. Women have a lower apnea threshold, compared to men and they are less likely to exhibit apneas during non-rapid eye movement sleep despite inspiratory flow limitation.7,8 It is possible that the above protective mechanisms disappear after menopause. Another point to remember when evaluating females for SDB is the fact that a good proportion of females with OSA present with insomnia rather than excessive daytime sleepiness. Shepertycky et al in a study of 260 patients found that 1 in 5 women with OSA had a presenting complaint of insomnia compared to 1 in 20 in men.9 We found similar findings in Saudi females with OSA (under review). We agree with the listed predictors of OSA in Ibrahim’s study. However, it is important for clinicians to realize that SDB in females is slightly different from that in males. Menopausal status is an important risk factor for OSA. Additionally, it is important to recognize that insomnia could be the presenting symptom of OSA in females. Focusing on daytime sleepiness in this group of patients may result in under-recognition of this serious disorder. ==== Refs REFERENCES 1 Ibrahim AS Almohammed AA Allangawi MH Sattar HAA Mobayed HS Pannerselvam B Predictors of obstructive sleep apnea in snorers Ann Saudi Med 2007 27 421 6 18059121 2 Young T Finn L Austin D Peterson A Menopausal status and sleep-disordered breathing in the Wisconsin Sleep Cohort Study Am J Respir Crit Care Med 2003 167 9 1181 5 12615621 3 Tishler PV Larkin EK Schluchter MD Redline S Incidence of sleep-disordered breathing in an urban adult population: the relative importance of risk factors in the development of sleep-disordered breathing Jama 2003 289 17 2230 7 12734134 4 Mohsenin V Gender differences in the expression of sleep-disordered breathing : role of upper airway dimensions Chest 2001 120 5 1442 7 11713117 5 Ware JC McBrayer RH Scott JA Influence of sex and age on duration and frequency of sleep apnea events Sleep 2000 23 2 165 70 10737333 6 Popovic RM White DP Upper airway muscle activity in normal women: influence of hormonal status J Appl Physiol 1998 84 3 1055 62 9480969 7 Krishnan V Collop NA Gender differences in sleep disorders Curr Opin Pulm Med 2006 12 6 383 9 17053485 8 Zhou XS Shahabuddin S Zahn BR Babcock MA Badr MS Effect of gender on the development of hypocapnic apnea/hypopnea during NREM sleep J Appl Physiol 2000 89 1 192 9 10904052 9 Shepertycky MR Banno K Kryger MH Differences between men and women in the clinical presentation of patients diagnosed with obstructive sleep apnea syndrome Sleep 2005 28 3 309 14 16173651