Correlation between the Epworth Sleepiness Scale and the Maintenance of Wakefulness Test in Obstructive Sleep Apnea Patients Treated with Positive Airway Pressure.

BACKGROUND: The Epworth sleepiness scale (ESS) is often used to evaluate the impact of treatment in patients with obstructive sleep apnea hypopnea syndrome (OSA). We aimed to evaluate the correlation between ESS and the Maintenance of Wakefulness Test (MWT) in a population of OSA patients treated with positive airway pressure (PAP). METHODS: We retrospectively included all patients during a 2-year period who were diagnosed with OSA in our sleep clinic and required PAP therapy. ESS was evaluated at baseline and after PAP therapy for all patients, and all had a concomitant MWT. Correlation between final ESS, change in ESS, and MWT were evaluated using Spearman's correlation. Given that MWT is considered as the gold standard, the diagnostic performance of ESS was evaluated against MWT. RESULTS: Hundred thirty-four OSA patients were included. At the time of MWT, 89.6% of the patients were compliant (PAP use ≥4hours/night), and only 9 (6.7%) had persistent sleepiness despite PAP treatment (mean sleep latency at MWT<19.4min). Moderate correlation was observed between final ESS and MWT (Spearman's correlation coefficient=-0.42), but no correlation was found between change in ESS and MWT. Diagnostic performance was as follows for final ESS: sensitivity=55.6%, specificity=84.8%, PPV=20.8%, and NPV=96.4%. CONCLUSIONS: ESS was moderately correlated with MWT in a population of OSA patients compliant with PAP therapy. In this population, ESS showed poor diagnostic performance in identifying patients with persistent excessive daytime sleepiness. CLINICALTRIALS. GOV IDENTIFIER: NCT03629834.

The relationship between metformin therapy and sleep quantity and quality in patients with Type 2 diabetes referred for potential sleep disorders.

AIMS: Given that sleep disorders are known to be related to insulin resistance, and metformin has favourable effects on insulin resistance and on ventilatory drive, we sought to determine whether metformin therapy was related to sleep variables in a group of patients with Type 2 diabetes. METHODS: We performed a retrospective, observational study of our centre's database for patients referred for potential sleep disorders and then compared metformin-treated patients with those not treated with the drug. All study patients had undergone the same standard polysomnographic procedure. A multivariate analysis was performed to establish whether or not there was an independent relationship between metformin use and sleep variables (after adjusting for age, gender, BMI, neck circumference, cumulated risk factors and insulin use). RESULTS: We studied 387 patients (mean ± sd age: 58.4 ± 10.8 years), of whom 314 had been treated with metformin. Total sleep time and sleep efficiency were higher in metformin-treated patients than in patients not treated with metformin [total sleep time: 6 h 39 min vs. 6 h 3 min, respectively (P = 0.002); sleep efficiency: 77.9 ± 12.3 vs. 71.5 ± 17.2%, respectively (P = 0.003)]. These differences persisted after adjustment for covariates and were observed even although metformin users had a higher BMI than did non-users (median 37.5 vs. 34.8 kg/m(2) ; P = 0.045). CONCLUSION: We showed that metformin therapy is associated with a longer sleep duration and better sleep efficiency. Randomized clinical trials are needed to confirm metformin's favourable effect on sleep quality and quantity.