The use of the CT90 value in predicting anxiety in OSA: could it be a useful parameter?

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of complete or partial obstruction of the upper airway leading to episodic desaturation. OSA patients often show symptoms of anxiety. Our study aimed to examine the presence and levels of anxiety in OSA and simple snoring relative to control subjects and to investigate the correlation between anxiety scores and polysomnographic, demographic, and sleepiness parameters.

The study included 80 OSA, 30 simple snoring, and 98 control cases. Demographic, anxiety, and sleepiness data of all subjects were acquired. The Beck Anxiety Inventory (BAI) was used to determine the level of anxiety. The Epworth Sleepiness Scale (ESS) was used to evaluate the sleepiness level of participants. In addition, polysomnography recordings of those in the OSA and the simple snoring group were acquired.

Significantly higher anxiety scores were found in patients with obstructive sleep apnea and simple snoring compared to the control group (p<0.01, p<0.01, respectively). From the polysomnographic data obtained from OSA and simple snoring subjects, the CT90 values (cumulative percentage of the time spent at saturations below 90%) and the AHI showed a weak positive correlation between the level of anxiety (p=0.004, r=0.271; p=0.04, r=0.196, respectively).

Our study concluded that polysomnographic data showing the depth and duration of hypoxia may be more reliable in showing neuropsychological disorder and hypoxia-related comorbidities in OSA. The CT90 value can be used as a measure in the assessment of anxiety in OSA. Its advantage is that it can be measured with overnight pulse oximetry along with in-laboratory PSG and HSAT (home sleep apnea test).