Polysomnographic characteristics of excessive daytime sleepiness phenotypes in obstructive sleep apnea: results from the international sleep apnea global interdisciplinary consortium.

STUDY OBJECTIVES: Excessive daytime sleepiness (EDS) is a major symptom of obstructive sleep apnea (OSA). Traditional polysomnographic (PSG) measures only partially explain EDS in OSA. This study analyzed traditional and novel PSG characteristics of two different measures of EDS among patients with OSA. METHODS: Sleepiness was assessed using the Epworth Sleepiness Scale (>10 points defined as "risk of dozing") and a measure of general sleepiness (feeling sleepy ≥ 3 times/week defined as "feeling sleepy"). Four sleepiness phenotypes were identified: "non-sleepy," "risk of dozing only," "feeling sleepy only," and "both at risk of dozing and feeling sleepy." RESULTS: Altogether, 2083 patients with OSA (69% male) with an apnea-hypopnea index (AHI) ≥ 5 events/hour were studied; 46% were "non-sleepy," 26% at "risk of dozing only," 7% were "feeling sleepy only," and 21% reported both. The two phenotypes at "risk of dozing" had higher AHI, more severe hypoxemia (as measured by oxygen desaturation index, minimum and average oxygen saturation [SpO2], time spent < 90% SpO2, and hypoxic impacts) and they spent less time awake, had shorter sleep latency, and higher heart rate response to arousals than "non-sleepy" and "feeling sleepy only" phenotypes. While statistically significant, effect sizes were small. Sleep stages, frequency of arousals, wake after sleep onset and limb movement did not differ between sleepiness phenotypes after adjusting for confounders. CONCLUSIONS: In a large international group of patients with OSA, PSG characteristics were weakly associated with EDS. The physiological measures differed among individuals characterized as "risk of dozing" or "non-sleepy," while "feeling sleepy only" did not differ from "non-sleepy" individuals.

Different components of excessive daytime sleepiness and the change with positive airway pressure treatment in patients with obstructive sleep apnea: Results from the Icelandic Sleep Apnea Cohort (ISAC).

Excessive daytime sleepiness includes both an inability to stay awake during the day and a general feeling of sleepiness. We describe different dimensions of daytime sleepiness in adults with moderate-severe obstructive sleep apnea (OSA) before and after 2 years of positive airway pressure (PAP) treatment. Using the Epworth Sleepiness Scale (score >10 defined as "risk of dozing") and Basic Nordic Sleep Questionnaire (feeling sleepy ≥3 times/week defined as "feeling sleepy"), participants were categorised into sleepiness phenotypes labelled non-sleepy, risk of dozing only, feeling sleepy only, or both symptoms. Participants repeated baseline assessments and PAP adherence was evaluated after 2 years. PAP-adherent subjects with sleepiness symptoms at both baseline and follow-up were considered persistently sleepy. Of the 810 participants, 722 (89%) returned for follow-up. At baseline, 17.7% were non-sleepy, 7.7% were at risk of dozing only, 24.7% were feeling sleepy only, and 49.9% had both symptoms. PAP adherence did not differ by baseline sleepiness phenotype. Patients with risk of dozing demonstrated greater PAP benefits for sleepiness symptoms than non-sleepy and feeling sleepy only phenotypes. Using these phenotypes, 42.3% of PAP users had persistent sleepiness; they had less severe OSA (p < 0.001), more persistent OSA symptoms and more often had symptoms of insomnia than patients in whom sleepiness resolved. Our present results, therefore, suggest that measuring the risk of dozing and the feeling of sleepiness reflect different sleepiness components and may respond differently to PAP. Patients feeling sleepy without risk of dozing may need more thorough evaluation for factors contributing to sleepiness before initiating treatment.

Definition of excessive daytime sleepiness in the general population: Feeling sleepy relates better to sleep-related symptoms and quality of life than the Epworth Sleepiness Scale score. Results from an epidemiological study.

Many different subjective tools are being used to measure excessive daytime sleepiness (EDS) but the most widely used is the Epworth Sleepiness Scale (ESS). However, it is unclear if using the ESS is adequate on its own when assessing EDS. The aim of this study was to estimate the characteristics and prevalence of EDS using the ESS and the Basic Nordic Sleep Questionnaire (BNSQ) in general population samples. Participants aged 40 years and older answered questions about sleepiness, health, sleep-related symptoms and quality of life. Two groups were defined as suffering from EDS: those who scored >10 on the ESS (with increased risk of dozing off) and those reporting feeling sleepy during the day ≥3 times per week on the BNSQ. In total, 1,338 subjects (53% male, 74.1% response rate) participated, 13.1% reported an increased risk of dozing off, 23.2% reported feeling sleepy and 6.4% reported both. The prevalence of restless leg syndrome, nocturnal gastroesophageal reflux, difficulties initiating and maintaining sleep and nocturnal sweating was higher among subjects reporting feeling sleepy compared to non-sleepy subjects. Also, subjects reporting feeling sleepy had poorer quality of life and reported more often feeling unrested during the day than non-sleepy subjects. However, subjects reporting increased risk of dozing off (ESS > 10) without feeling sleepy had a similar symptom profile as the non-sleepy subjects. Therefore, reporting only risk of dozing off without feeling sleepy may not reflect problematic sleepiness and more instruments in addition to ESS are needed when evaluating daytime sleepiness.

Serum ferritin and obstructive sleep apnea-epidemiological study.

PURPOSE: Ferritin is an intracellular iron storage protein and a marker of inflammation. Studies have shown that subjects with obstructive sleep apnea (OSA) have higher levels of circulating pro-inflammatory cytokines, but little is known about the association between ferritin and OSA. The aims of the study were to evaluate serum ferritin (S-Ferritin) levels in OSA patients compared to levels in the general population and also examine the effect of obesity level and treatment with positive airway pressure (PAP) on S-Ferritin levels. METHODS: The OSA subjects (n = 796) were part of the Icelandic Sleep Apnea Cohort. The control subjects (n = 637) were randomly chosen Icelanders who participated in an epidemiological study. Propensity score (PS) methodologies were employed to minimize selection bias and strengthen causal inferences when comparing non-randomized groups. S-Ferritin levels were measured and all participants answered the same detailed questionnaire about sleep and health. Only OSA patients underwent a sleep study and were re-invited for a 2-year follow-up. RESULTS: S-Ferritin levels were significantly higher in OSA males than controls (213.3 vs. 197.3 µg/L, p = 0.007). However, after adjusting for confounders and using our PS methodology, no significant difference was found. S-Ferritin levels were not correlated with severity of OSA, obesity level, or clinical symptoms. Also, no significant change in S-Ferritin levels was found with 2 years of PAP treatment. CONCLUSIONS: S-Ferritin levels are comparable in OSA patients and controls and do not change consistently with obesity level or PAP treatment in our sample.