[Association between subjective and objective sleepiness in obstructive sleep apnea hypopnea syndrome patients]

Objective: To examine the association between subjective sleepiness and objective sleepiness in Chinese obstructive sleep apnea hypopnea syndrome (OSAHS) patients. Methods: A total of 1 660 patients meeting the diagnostic criteria of OSAHS based on overnight polysomnography from West China Hospital, Sichuan University in the period from Jul 2010 to Jul 2014 were enrolled in the study. The Epworth Sleepiness Scale (ESS) and Multiple Sleep Latency Test (MSLT) were to evaluate subjective and objective sleepiness, respectively. The subjects were categorized into quartiles [A (0-4) (n=406), B (5-7) (n=325), C (8-12) (n=443), D(13-24) (n=486) groups] based on the ESS score distribution. Survival analysis was used to characterize the association between the ESS score and the mean sleep latency (MSL). Results: The apnea hypopnea index (AHI) in D group was higher than other three groups [(58.7±26.1) vs (36.8±24.2), (42.6±26.7), (45.7±26.6) events/h, all P<0.05]. The mean sleep latency in D group was shorter than other three groups [(8.0±4.6) vs (10.9±4.4), (10.3±4.8), (9.4±4.5) min, all P<0.05]. The Kaplan-Meier survivor functions across the ESS score quartiles were distinct and fourth quartiles were progressively associated with a greater tendency for falling asleep (χ(2)=77.76, P<0.001 by Log-rank test) in the daytime (The percentages of awaking patients in fourth quartiles were progressively lower at the same time). The adjusted hazard ratios for sleep onset during the MSLT for the group B, C and D were 1.05 (95%CI: 0.90-1.22), 1.22 (95%CI: 1.07-1.40), and 1.38 (95%CI: 1.20-1.60), respectively, comparing to group A. Conclusion: Subjective report of daytime sleepiness is consistent with the objective sleepiness in OSAHS patients.