The Hourly Apnea-Hypopnea Duration Better Correlates with OSA-Related Nocturnal Hypoxemia and Excessive Daytime Sleepiness Rather Than AHI.

BACKGROUND

The apnea-hypopnea index (AHI) has limitations in assessing nocturnal hypoxemia and excessive daytime sleepiness (EDS) in obstructive sleep apnea (OSA) patients. This study evaluated whether hourly apnea-hypopnea duration (HAD) and mean apnea-hypopnea duration (MAD) could complement or outperform AHI.

METHODS

This study included 1069 OSA patients, of whom 754 completed the Epworth Sleepiness Scale (ESS). Multivariable regression models evaluated the associations between AHI, MAD, HAD, and nocturnal hypoxemia, and standardized scores were used for comparison. The predictive ability of AHI, MAD, and HAD models for EDS was evaluated using goodness-of-fit indices, and receiver operating characteristic (ROC) curve analysis was performed using bootstrapping techniques.

RESULTS

Nocturnal hypoxemia was observed in 317 participants (29.65%). Patients with nocturnal hypoxemia had significantly higher AHI (43.19 ± 18.41 vs 21.78 ± 14.73 events/hour, P < 0.001) and longer HAD (16.71 ± 7.48 vs 8.24 ± 5.40 minutes, P < 0.001). After adjusting for age, sex, and BMI, AHI and HAD were still significantly associated with nocturnal hypoxemia (P < 0.05). Standardized scores analysis revealed that HAD had the strongest association with nocturnal hypoxemia (HAD: OR = 3.69, 95% CI: 3.06-4.46, P < 0.0001; AHI: OR = 3.48, 95% CI: 2.90-4.18, P < 0.0001; MAD: OR = 1.01, 95% CI: 0.88-1.15, P = 0.9314) and mean SpO (HAD: β = -0.91, 95% CI: -1.02--0.79, P < 0.0001; AHI: β = -0.85, 95% CI: -0.97--0.74, P < 0.0001; MAD: β = 0.00, 95% CI: -0.12-0.12, P = 0.9595), outperforming AHI and MAD. The HAD model showed the best fit for predicting EDS, with an area under the curve of 0.61 at a threshold of 5.63.

CONCLUSION

The HAD better correlates with OSA-related nocturnal hypoxemia and EDS rather than AHI. The duration of respiratory events warrants more investigation in clinical assessment.