Examining the association between CT-defined low tongue posture and CPAP adherence

Area of Science:

• Medical Imaging
• Sleep Medicine
• Respiratory Medicine

Background:

• Continuous Positive Airway Pressure (CPAP) therapy is a primary treatment for Obstructive Sleep Apnea (OSA).
• Patient adherence to CPAP therapy is a significant challenge impacting treatment efficacy.
• Low tongue posture (LTP) has been anecdotally linked to OSA severity and treatment outcomes.

Purpose of the Study:

• To investigate the association between CT-defined low tongue posture (LTP) and adherence to CPAP therapy in adults with OSA.
• To operationalize LTP using a specific metric on sagittal CT scans: the tongue-palate air gap.
• To determine if LTP can predict CPAP adherence at 3 months post-initiation.

Main Methods:

• Retrospective analysis of 430 adult OSA patients (Apnea-Hypopnea Index ≥ 20).
• Patients underwent Polysomnography (PSG), CT imaging, and CPAP initiation.
• CPAP adherence was assessed using device data at 3 months; LTP was defined by mid-sagittal CT.
• Logistic regression analyzed factors associated with good adherence (≥70% and ≥50% of nights with ≥4 hours use).

Main Results:

• CT-defined LTP was present in 26.7% of patients (115/430).
• Patients with LTP exhibited significantly lower average CPAP adherence (39.6% vs. 54.1%, p < 0.001).
• Multivariate analysis revealed LTP was associated with lower odds of good adherence at both 70% (aOR 0.447) and 50% (aOR 0.496) thresholds.
• Model specificity for LTP was limited at the 70% adherence threshold (22.5%) but improved at the 50% threshold (68.3%).

Conclusions:

• CT-defined low tongue posture is significantly associated with poorer CPAP adherence in OSA patients.
• The current CT definition of LTP lacks standardization and shows limited specificity, particularly at higher adherence thresholds.
• LTP should be considered an adjunctive risk marker for CPAP adherence challenges rather than a standalone screening tool.