# A Scientometric Review of Obstructive Sleep Apnea and Obesity
## 1 Introduction  
Obstructive sleep apnea (OSA) is a condition involving repeated episodes where the upper airway completely or partially collapses, which often leads to oxygen desaturation or sleep arousal [1; 2]. There have been many studies indicating the high prevalence of OSA across many different populations as well as subgroups (e.g., [3; 4; 5; 6; 7; 8; 9], see [10; 11] for reviews). For example, a systematic review by [PERSON] et al. [10] found that the overall prevalence of sleep apnea ranged from 9 to 38% for \(\geq\)5 events/hour apnea-hypoapnea index (AHI), where the AHI is a major index of the severity of sleep apnea. Moreover, the prevalence of OSA has been on the rise in recent times and affects both developed and developing countries [12]. This worrying trend is a cause of concern due to the adverse health outcomes and mortality associated with OSA.  
OSA has been linked with many clinical health conditions, including hypertension as well as cardiovascular and metabolic diseases [13; 14; 15]. In particular, the Sleep Heart Health Study was one of the first studies to examine the association between OSA and cardiovascular disease and found modest to moderate associations between sleep-disordered breathing and cardiovascular disease [16]. Notably, [PERSON] et al. [17] found that severe OSA led to a significant increase in risk of both fatal and non-fatal cardiovascular events. Many studies have also demonstrated independent associations between sleep apnea and increasing insulin resistance [8; 13; 18], although there have been inconsistent results surrounding the association between OSA and diabetes [14; 19; 20]. Hence, there is increasing recognition of OSA as a major public health burden in and of itself, alongside its contribution to the development of cardiovascular, metabolic, and psychiatric disorders.  
One factor contributing to the increase in OSA is the increasing obesity rates. Across the globe, obesity rates have doubled since 1980 [21], and recently, the United States ofAmerica has reported that the prevalence of obesity in adults was 41.9% [22]. Obesity has been established in many studies as one of the strongest risk factors of OSA [3; 8; 10; 23; 24; 25]. For example, there is evidence from a follow-up of the Wisconsin Sleep Cohort Study demonstrating that a 10% change in body weight is associated with an accompanying increase in approximately 30% in the AHI [24]. Similarly, [PERSON] et al. [26] demonstrated relations between modest changes in weight and sleep-disordered breathing, where men with \(\geq\)10 kg weight gain were approximately five times more likely to show a large increase in the respiratory disturbance index. There are a number of factors linking obesity to sleep apnea. First, the increased parapharyngeal fat deposit and neck fat results in upper airway obstruction during sleep through the narrowing of the airway [27; 28]. Second, increased abdominal girth and a lying position result in a decrease in lung volume, which exacerbates the hypoxia through the reduction of traction on the upper airway [29]. Third, upper airway collapsibility has been found to be higher in obese individuals compared to nonobese individuals [30]. Fourth, obesity has been proposed to modulate neuromuscular control in the upper airway [28]. Given the continuing rise in obesity rates across the globe, it can be expected that OSA will continue to grow as a public health concern, further exacerbating health problems commonly associated with obesity.  
The aim of this study is the identification of key publications in the literature on OSA and obesity, the main thematic trends, and existing gaps using a data-driven approach. To do so, a document co-citation analysis (DCA) was conducted [31; 32]. From the results of the scientometric analysis, publication trends and the links between individual works can be derived.