**2. OSA epidemiology**

### **2.1. Prevalence**

Due to various definitions of respiratory events and differences in study design, contradictory variable prevalence rates of OSA are reported. The American Academy of Sleep Medicine published the first guidelines to standardize the definition of OSA; however, the standardi‐ zation of OSA definition only expanded the diagnostic criteria.[1] According to the Wisconsin sleep cohort study, the estimated prevalence of moderate to severe sleep breathing disorder in the United States for the period of 1988–2011 ranged from 3% to 17% in adults depending on sex and age; OSA seemed to affect especially middle-aged and elderly men and has increased substantially over the last two decades in the US. [9] In Morocco, however, OSA prevalence ranges from 5, 4% to 7, and 9% in the general population. [10] De Backer (2013) reported that epidemiological studies investigating the prevalence of OSA are all biased because there is a lack of a uniform definition. He also indicated that the prevalence of an AHI of >5 events per hour in the general population (without taking into account symptoms of sleepiness) has been estimated to be 24% in the male population. When symptoms of sleepiness are also taken into account, this prevalence goes down to 4% in males and 2% in females. [11]

#### **2.2. Risk factors**

In the literature on OSA, most researches agree that risk factors for OSA include obesity, upper airway and craniofacial abnormalities, gender, age, alcohol consumption and cigarette smoking. [12] Obesity, particularly central or upper body fat distribution, with increased neck circumference (collar size) is a main risk factor for OSA. But this association may be less important with the elderly. In non-obese patients, craniofacial abnormality like micrognathia and retrognathia may also be considered as a risk factor leading to OSA. [13]

Aging is also associated with higher OSA prevalence. Still, it is not clear if OSA in the elderly compared to middle-aged adults manifests itself the same way; middle age and over-weight adult men seem to have the highest prevalence of OSA. However, after menopause, prevalence seems to be the same for both women and men. [1]Some studies have examined craniofacial features among different ethnic groups; their objective was to investigate whether ethnicity differences had an effect on the prevalence of OSA. These studies reported an increased risk of OSA among African-Americans, Latinos and Asians. [14]-[17] Wong et al. (2005) claimed that the hyoid bone was located more caudally in Chinese subjects and may be a severity indicator in this population. [18] In addition, OSA prevalence seems to be much higher in patients with cardiac or metabolic disorders than in the general population. Other factors such as heredity, hormonal change, sedative hypnotics and supine sleep position have also been described as risk conditions for developing OSA. [11, 12]

#### **2.3. Mortality and morbidity**

managing and treating OSA. This chapter gives a comprehensive account of the literature on OSA and underlines the role of orthodontists in managing OSA with a view to improve the

Due to various definitions of respiratory events and differences in study design, contradictory variable prevalence rates of OSA are reported. The American Academy of Sleep Medicine published the first guidelines to standardize the definition of OSA; however, the standardi‐ zation of OSA definition only expanded the diagnostic criteria.[1] According to the Wisconsin sleep cohort study, the estimated prevalence of moderate to severe sleep breathing disorder in the United States for the period of 1988–2011 ranged from 3% to 17% in adults depending on sex and age; OSA seemed to affect especially middle-aged and elderly men and has increased substantially over the last two decades in the US. [9] In Morocco, however, OSA prevalence ranges from 5, 4% to 7, and 9% in the general population. [10] De Backer (2013) reported that epidemiological studies investigating the prevalence of OSA are all biased because there is a lack of a uniform definition. He also indicated that the prevalence of an AHI of >5 events per hour in the general population (without taking into account symptoms of sleepiness) has been estimated to be 24% in the male population. When symptoms of sleepiness are also taken into account, this prevalence goes down to 4% in males and 2% in females. [11]

In the literature on OSA, most researches agree that risk factors for OSA include obesity, upper airway and craniofacial abnormalities, gender, age, alcohol consumption and cigarette smoking. [12] Obesity, particularly central or upper body fat distribution, with increased neck circumference (collar size) is a main risk factor for OSA. But this association may be less important with the elderly. In non-obese patients, craniofacial abnormality like micrognathia

Aging is also associated with higher OSA prevalence. Still, it is not clear if OSA in the elderly compared to middle-aged adults manifests itself the same way; middle age and over-weight adult men seem to have the highest prevalence of OSA. However, after menopause, prevalence seems to be the same for both women and men. [1]Some studies have examined craniofacial features among different ethnic groups; their objective was to investigate whether ethnicity differences had an effect on the prevalence of OSA. These studies reported an increased risk of OSA among African-Americans, Latinos and Asians. [14]-[17] Wong et al. (2005) claimed that the hyoid bone was located more caudally in Chinese subjects and may be a severity indicator in this population. [18] In addition, OSA prevalence seems to be much higher in patients with cardiac or metabolic disorders than in the general population. Other factors such as heredity, hormonal change, sedative hypnotics and supine sleep position have also been

and retrognathia may also be considered as a risk factor leading to OSA. [13]

described as risk conditions for developing OSA. [11, 12]

physical, mental and social status of patients diagnosed with OSA.

364 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**2. OSA epidemiology**

**2.1. Prevalence**

**2.2. Risk factors**

Epidemiologic data have shown a strong association between untreated obstructive sleep apnea and incident cardio and cerebrovascular morbidity and mortality. [19, 20] These comorbid conditions may be due, in part, to common risk factors (i.e. obesity and hypertension), and also to hypoxemia-hypercapnia, which can lead to vascular dysfunctions. [21] In an18 year mortality follow-up conducted on the population-based Wisconsin Sleep Cohort sample (n = 1522), Young et al. found a significant mortality risk with untreated sleep breathing disorder (SBD). They underscored the need for early diagnosis and treatment of SBD, indicated by frequent episodes of apnea and hypopnea, regardless of sleepiness symptoms.[20]A recent review of OSA in adults reported an increased risk of morbidity and mortality associated with OSA, which reached its peak at 55 years of age. [12], This association seems to disappear after 70 yrs. [22]Sampaio et al., 2012 suggested that women revealed more psychological morbidity associated with OSAS. Therefore, it seems extremely important to look at women as potential patients for sleep apnea. [23] However, Gozal and Kheirandish-Gozal highlighted the potential interaction between gene polymorphisms, organ vulnerability, and the phenotypic expression of OSA and suggested that it should be identified and incorporated into future prediction schemes of morbidity risks associated with OSA. [24]
