On Treatment but Still Sleepy

Cause and Management of Residual Sleepiness in Obstructive Sleep Apnea

Sandrine H. Launois; Renaud Tamisier; Patrick Lévy; Jean-Louis Pépin


Curr Opin Pulm Med. 2013;19(6):601-608. 

In This Article

Prevalence of Residual Sleepiness in Obstructive Sleep Apnea

Few studies have specifically investigated the prevalence of residual sleepiness in OSA and none has done so prospectively. One difficulty in assessing the real prevalence of residual sleepiness is that the available studies thus far have not always excluded common causes of sleepiness, such as depression or BIISS. For instance, in a group of more than 200 morbidly obese, sleepy OSA patients evaluated in a tertiary care facility in Greece, 6 months after CPAP initiation, an extremely high rate of residual sleepiness was present (55% of patients), despite a nightly CPAP usage of 6 h; however, a significant relationship with depression was established.[28] In addition, although no correlation was demonstrated in this particular group of sleepy individuals, obesity in itself may be associated with sleepiness.[5] In 80 initially sleepy, moderate-to-severe OSA patients treated in a French university hospital, approximately 20% remained sleepy despite an average of more than 5 h of CPAP/night.[29] Interestingly, the prevalence of residual sleepiness was 25% 3 months after treatment initiation, but only 19% at the 1-year follow-up.[29] Finally, two large prospective multicenter studies in France (502 and 1047 patients, respectively) were conducted on an unselected population of OSA patients representative of 'real life' patient management to determine the prevalence of residual sleepiness.[17,30] In the first of these studies, 12% of patients using CPAP for more than 3 h/night at the 1-year follow-up visit were still sleepy. After exclusion of patients with associated sleep disorders, depression or sedative medication use, the prevalence of 'true' residual sleepiness was 6%.[30] In the largest study so far, including over a thousand patients, we recently found an overall rate of residual sleepiness of 13%.[30] Patients who were initially sleepy had a higher prevalence of residual sleepiness (18.3%) than those who were not (5.6%; Fig. 1).[17] The prevalence of residual sleepiness significantly decreased with longer CPAP use, with 8.7 vs. 18.5% of patients using CPAP at least 6 h/night vs. less than 4 h/night (Fig. 1).

Figure 1.

Residual sleepiness (RS) and continuous positive airway pressure (CPAP) compliance in a French multicenter retrospective study of 1047 obstructive sleep apnea patients. Prevalence rates of residual sleepiness in all (n=1047; gray bars) and in initially sleepy (Epworth Sleepiness Scale Score, ESS ≥10/24, n=602; black bars) patients among different CPAP use categories. Significant difference for comparison of residual sleepiness prevalence between all patients and initially sleep patients (all had a CPAP use ≥3 h/night by design). *,#Significant difference for comparison of patients using CPAP more than 6 h/night with patients using CPAP 3–4 h and 4 h–5 h/night, respectively. Test used: one-way analysis of variance (ANOVA) with post-hoc Bonferroni correction. Adapted from [17].

Overall, based on retrospective studies, the prevalence of residual sleepiness can be estimated at approximately 10%, once all confounding causes of sleepiness have been excluded. Thus, a large number of OSA patients are 'on treatment but still sleepy'. It is, therefore, disconcerting to see that so few studies have focused on better characterizing this syndrome.