Ability of Upper Airway Metrics to Predict Obstructive Sleep Apnea Severity: A Systematic Review.

Objectives: The lack of consensus regarding the association between airway narrowing and the severity of obstructive sleep apnea (OSA) presents a significant challenge in understanding and diagnosing this sleep disorder. The study aimed to systematically review the literature to investigate the relationship between upper airway measurements and the severity of OSA defined by the apnea-hypopnea index (AHI).

Methods: PubMed, Scopus and Web of Science were systematically searched on the 21st of March 2023 for articles of OSA patients as diagnosed by polysomnography, investigating the correlation between upper airway measurements and AHI using CBCT or MDCT. Quality assessment was done using the New Castle-Ottawa Scale. The results were subsequently synthesized descriptively.

Results: The database search identified 1253 results. Fourteen studies, encompassing 720 patients, met the eligibility criteria. Upper airway length showed moderate to weak positive correlation with AHI. Minimal cross-sectional area had varying correlations with AHI, ranging from strong negative to no correlation. Nasopharyngeal volumes showed moderate negative to weak correlations with AHI. Total upper airway volume ranged from strong negative to weak correlation with AHI. Other measurements exhibited weak or very weak correlations with AHI.

Conclusions: Among the variables investigated, the minimal cross-sectional area and, to a lesser extent, the volume of the upper airway in OSA patients demonstrated the most promising correlation with the AHI. However, the preponderance of evidence suggests that upper airway length, cross-sectional area and volume as measured by CBCT or MDCT are weak predictors of OSA.