Current sleep-disordered breathing screening parameters are built on the phenotype characteristics of the male population, rather than the phenotype characteristics of male and female populations. Often, patients who receive treatment show moderate to severe obstructive sleep apnea (OSA) specificity, while those who are within the bracket of upper-airway resistance syndrome (UARS) or mild OSA are merely sensitive and may not receive treatment.
Generally, men present clinical symptoms at or above the threshold of OSA, whereas women present symptoms indicative of mild OSA or UARS. The National Sleep Foundation estimates the male to female sleep apnea diagnosis ratio is 2:1. The gender gap is not the result of women unaffected by the condition, but the androcentric standard for which the condition is measured. The variance in male versus female pathophysiology places many patients who present characteristics linked to the female phenotype outside of treatment.
Oxidative stress as a common denominator underlying a wide spectrum of diseases and conditions is becoming increasingly obvious. Both conditions cause blood oxygen desaturation and are linked to the development of hypertension, metabolic syndrome, and cardiovascular syndrome. Also, research from the Wisconsin Sleep Cohort Study suggests a link between oxygen desaturation and cancer.
“Clearly, there is a correlation, and we are a long way from proving that sleep apnea causes cancer or contributes to its growth,” said F. Javier Nieto, MD, PhD, MPH, chair of the department of population health sciences at the Wisconsin School of Medicine and Public Health.
“But animal studies have shown that the intermittent hypoxia, an inadequate supply of oxygen, that characterizes sleep apnea promotes angiogenesis—increased vascular growth—and tumor growth. Our results suggest that sleep-disordered breathing is also associated with an increased risk of cancer mortality in humans,” said Nieto.
Androcentricsm is nothing new. The Journal of Women’s Health estimates that 25% of the female population is at high risk for OSA since women’s biological sex differences (hormones, weight, size, etc), symptomology, and apnea hypoxia index/respiratory disturbance index do not meet the male-centric criteria. Milder forms are left to grow until they are in an intensified state.
Also, UARS patients may present consequences in sleep structure that conventional polysomnography parameters do not identify, report researchers from the Universidade Federal de São Paulo in Brazil. Plus, it is not until pregnancy or menopause that the condition makes itself obvious and is diagnosed as treatable.
The Role of Diagnosis
The current sleep-disordered breathing diagnostic parameters determine the condition, severity, and treatment. While it may seem that diagnosis is straightforward, additional layers must be considered. Functional changes that accompany a condition differ depending on their phenotypic sex. Pathophysiologic trajectory is influenced by body mass index, neck size, and airway size.
There are reasons why patients with UARS and mild OSA are undiagnosed or misdiagnosed. Decision thresholds are based on a number of variables. For example, historical conditioning has shaped ontology, creating spectrum bias and likelihood ratios. Researchers from Umeå University have shown unjustified differences in the investigation and treatment of male and female patients in clinical medicine, though these measures are not evidence-based.
Other variables include limitations of sensitivity and specificity, such as sensitivity to rule out disease or specificity to rule in disease; limitations of positive and negative predicative values; prolonged discussion as to how UARS is delineated on the sleep-breathing disorder spectrum; biased polysomnographic parameters; and limitations of insurance.
Diagnosis is the compass for treatment. Patients who present characteristics that fall within the current diagnostic population parameters will be directed to a form of current standard therapy, including continuous positive airway pressure (CPAP) mask therapy, standard sleep oral appliances, and surgery in some cases, depending on the obstruction location. (UARS is being trialed with CPAP because it does not qualify for the current treatment parameters.) Additionally, more than one form of therapy may be recommended depending on the advice of the medical team.
UARS and mild-OSA patients present symptoms that may be interpreted as psychological distress rather than physiological distress. Those who do not meet the industry standard are often rerouted in the direction of prescription medication while the underlying condition continues to grow.
Both males and females suffer from sleep-disordered breathing, yet the parameters of the current diagnostic framework are centered around the secondary sex characteristics and behavior of the male population, rather than the secondary sex characteristics and behavior of both populations. While some patients with UARS or mild OSA receive treatment including CPAP and standard sleep oral appliances, there is still a large part of the population who does not.
Dr. Cortes is a biological dental-sleep medicine expert who owns and operates Sleep Fitness LLC, a branch of Cortes Advanced Dentistry, in Manhattan, NY. Unlike traditional dentistry that primarily addresses the teeth, she focuses on the teeth and their relationship to the body as a whole, attending to chronic sleep-breath related conditions such as sleep apnea, upper airway resistance syndrome, and craniofacial deficiencies. She is a member of the American Board of Dental Sleep Medicine, American Board of Craniofacial Pain, American Board of Craniofacial Dental Sleep Medicine, American Board of Sleep Breathing, and American Board of Aesthetic Dentistry. She can be reached at email@example.com.