BOSTON – Treatment with continuous positive airway pressure does double duty in patients with obstructive sleep apnea by improving their mood while promoting restful sleep, Dr. Charles Bae reported at the annual meeting of the Associated Professional Sleep Societies.

In a retrospective study of 769 adults with OSA, the Cleveland Clinic neurologist and his colleagues observed a significant decrease in depressive symptoms as measured by the Patient Health Questionnaire 9 (PHQ-9) among patients who used a CPAP device.

“A number of studies have confirmed an association between obstructive sleep apnea and depressive symptoms, but until now none have looked specifically at the link between CPAP and symptom severity as measured by PHQ-9,” Dr. Bae said in an interview. “Our goal was to assess the impact of CPAP therapy on patient mood by measuring the change in depressive symptoms following treatment.”

Toward this end, the investigators reviewed data for all of the adult patients (18 years or older) with OSA seen at the Cleveland Clinic Sleep Disorders Center from January 2008 to July 2011. Patients who met study criteria had been treated with CPAP and had at least two outpatient visits (one before and one within 30 days after initiating CPAP), had completed the PHQ-9 questionnaire, and had a pre-CPAP score on the questionnaire of at least 5, Dr. Bae said.

Of the 769 study patients (mean age, 51.8 years), 654 were characterized as adherent to CPAP therapy based on self-reported use of the device 4 or more hours per night; the remaining 115 used the device either inconsistently or for fewer than 4 hours per night and were considered nonadherent. The baseline PHQ-9 scores for patients in the adherent and nonadherent groups were similar, at 11.2 and 11.8, respectively. Significant decreases from baseline in PHQ-9 scores were observed in both groups, but the difference was “significantly more robust” in the adherent group at 3.8, compared with 2.0 in the nonadherent group, Dr. Bae reported.

The results were even more robust among patients who had reported sleepiness at baseline, according to Dr. Bae. Specifically, in the patients who had a minimum score of 10 on the Epworth Sleepiness Scale prior to CPAP, ESS scores decreased by 4.0 in the adherent group vs. 2.8 in the nonadherent group, he said. In the CPAP-adherent group, there was a significant difference between sleepy vs. nonsleepy patients in their average decrease in PHQ-9 score. “The PHQ-9 score dropped 4.3 points among patients whose [ESS] score was at least 10 at baseline, compared with 3.1 points among those whose score was less than 10,” he said.

Marital status was also examined as a covariate in the multiple regression model and appeared to have an effect. The mean PHQ-9 score decrease among the 475 married patients after CPAP was 4.0, compared with 3.0 among single patients and 2.3 among divorced patients, Dr. Bae said, noting that the difference between married and divorced patients was significant.

While the specific mechanisms contributing to the mood improvements associated with CPAP treatment in OSA patients can’t be ascertained from a retrospective study, the findings are fairly intuitive, according to Dr. Bae. When people sleep better, “a lot of things look better,” he said.

Dr. Bae disclosed no relevant conflicts of interest.