Association between nonrestorative sleep status and sleep apnea syndrome: A cross-sectional and longitudinal study using health check-up and health insurance claims data in Japan

Background

Nonrestorative sleep (NRS) refers to the subjective experience of feeling unrefreshed upon awakening that is not attributed to lack of sleep; NRS is also observed in patients with sleep apnea syndrome (SAS). We investigated the prevalence of NRS among health check-up participants using a single item and further investigated the relationship between NRS status and newly diagnosed SAS using health insurance claims data.

Methods

We extracted data associated with 93215 participants who underwent health check-ups in 2014 and answered a sleep-related question from a health insurance claims and health check-up database. Patients with SAS were identified via confirmation of the diagnosis and their use of continuous positive airway pressure (CPAP) therapy. Participants without a diagnosis of SAS were followed up for up to 6 years. A Cox proportional hazard model was used to determine whether NRS status was significantly associated with SAS.

Results

The mean age of the participants was 52.3 ± 16.7 years (men: 58.4 %, women: 41.6 %); 32.0 % had NRS status, and 0.8 % had SAS. During the 6-year observation period, among 92050 people, 2.2 % of the patients in the NRS group and 1.3 % of the patients in the non-NRS group were newly diagnosed with SAS. Even after adjusting for other factors, NRS status was a significant risk factor for newly diagnosed SAS (hazard ratio: 1.62, 95 % CI: 1.46–1.81).

Conclusions

NRS status was a significant risk factor for newly diagnosed SAS. NRS status might be useful as a health check-up screening tool for undiagnosed or subclinical SAS.