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Increased incidence of sleep apnea in psychiatric outpatients

Suhayl Nasr, MD

Nasr Psychiatric Services, Michigan City, IN, USA

Indiana University, Department of Psychiatry, Bloomington, IN, USA

University of Notre Dame, Department of Psychology, Notre Dame, IN, USA

Burdette Wendt

Nasr Psychiatric Services, Michigan City, IN, USA

Shilpa Kora, BSc

Nasr Psychiatric Services, Michigan City, IN, USA

BACKGROUND: The rate of mood disorders in patients in sleep centers has been the subject of many studies, yet little has been published on the incidence of sleep apnea in psychiatric patients.

METHODS: A retrospective chart review was performed on 330 consecutively seen psychiatric outpatients. Medication history, demographics, and the results of patients’ most recent Quick Inventory of Depressive Symptomatology (QIDS) were collected. Patients were checked for a history of apnea through a review of session notes and the results of any polysomnogram that the patient had on file.

RESULTS: Of the patients studied, 9.7% were positive for sleep apnea. They required a significantly higher number of medications (3.2 vs 2.4; P < .001). They also scored significantly higher on 3 items on the QIDS: late insomnia (1.0 vs 0.55; P < .01), reduced energy level (1.2 vs 0.76; P < .02), and decreased general interest (1.0 vs 0.64; P < .04). Middle age in men (age 45 to 64) and higher body mass index both in men and women were also associated with a higher frequency of sleep apnea.

CONCLUSIONS: Sleep apnea is more prevalent in psychiatric outpatients than in the general population. Identification of this comorbid condition will likely result in better treatment outcomes.

KEYWORDS: sleep apnea, depression, pharmacotherapy



Obstructive sleep apnea (OSA) is suspected when individuals report interrupted sleep or excessive daytime sleepiness, or their bed partners report excessive snoring. The diagnosis is confirmed with a sleep study showing at least 5 apnea/hypopnea episodes (AHIs) per hour. The prevalence of obstructive sleep apnea is considered to vary from 2% for women to 4% for men.1 Bixler et al reported that the prevalence of OSA increases with age, up to a peak prevalence of 5.4% among men between age 50 and 592 and 3.3% among women between age 60 and 69.3 Bixler et al also reported a higher prevalence of OSA in female patients with a body mass index (BMI) >32.3 (4.85% vs 0.4%) than for those with a BMI <32.3, and among male patients with a BMI >31.1 (13.8% vs 2.0%) than for those with a BMI <31.1.3

OSA patients often have symptoms that mimic depression, such as fatigue, irritability, depressed mood, and poor concentration. Ohayon surveyed a random European sample of 18,980 individuals and reported that 800 out of 100,000 people had both depression and OSA. Almost 20% of patients with one condition also had the other.4 Sharafkhaneh et al studied over 4 million Veterans Health Administration records and reported a prevalence of OSA of 2.91%. The rate of comorbidity in these patients was 21.8% for depression, 16.7% for anxiety, 11.9% for posttraumatic stress disorder (PTSD), 5.1% for psychosis, and 3.3% for bipolar disorder.5 In a long-term follow-up of patients with OSA using continuous positive airway pressure (CPAP), Schwartz and Karatinos found a significant decrease in depressive symptoms, as measured by the Beck Depression Inventory.6 The only published study of sleep apnea in psychiatric patients is that of Reynolds et al, who reported that 3 out of 17 older depressed patients had OSA compared with 1 out of 23 controls.7

The following is a report on the prevalence of OSA in a consecutive series of 330 psychiatric outpatients from a randomly selected time period and their treatment characteristics.


A chart review was performed on 330 consecutively seen psychiatric outpatients at Nasr Psychiatric Services, a private psychiatric group practice in Indiana. The charts were reviewed for a history of sleep apnea in 2 ways: actual polysomnograms or reports of use of a CPAP machine for diagnosed OSA. Fourteen patients had a polysomnogram on file (11 of which were positive), 11 patients reported a diagnosis of OSA on their first office visit, and 10 patients were diagnosed by means of a sleep study completed between their first office visit and the data collection period. Medication history, demographics, QIDS scores from the patient’s initial and most recent visits, and clinical diagnoses were collected for all patients. The QIDS—a 16-item, self-report test that measures the severity of depressive symptoms—was routinely administered to all patients at their initial screening and subsequent visits. The Institutional Review Board of St. Anthony Memorial Health Centers authorized collection of de-identified data for this study.

Statistical analysis for this data set was done using SPSS version 9.0. Chi-square and binomial tests were used to compare these data with the general population study by Bixler et al. Two-tailed t tests were used to check for significant differences between patients with and without sleep apnea.


Overall, 9.7% of the patients studied were positive for OSA. The average age of patients in the study was 51.0 years (+/-15, range 16 to 90). Sixty-seven percent of the patients were female and 33% were male. Diagnoses included: unipolar depression, 54%; bipolar disorder, 29%; other psychiatric condition, 17%. Over 95% of patients were Caucasian. There was no significant age difference between patients with and those without OSA (55.3 [±8.9] vs 50.6 [±15.5]).

The average QIDS score from the patients’ initial visit showed no significant difference between apnea patients and nonapnea patients (14.8 [±6.6] vs 14.5 [±7.4]) (a higher score indicates increased symptomatology). However, on their last observed QIDS, patients without OSA achieved a lower score of 7.7 (±5.1), compared with patients with OSA (9.5 [±6.2]; P = .08). Patients with OSA scored significantly higher on the following 3 items of the QIDS than did patients without OSA: late insomnia (QIDS SR16 item 3, 1.0 [±1.2] vs 0.55 [±1.0]; P < .01), general interest (QIDS SR16 item 13, 1.0 [±1.2] vs 0.64 [±0.9]; P < .04), and energy level (QIDS SR16 item 14, 1.2 [±1.1] vs 0.76 [±0.9]; P < .02).

Concerning BMI, 0% of underweight patients, 5% of normal weight patients, 14% of overweight patients, and 15% of obese patients were positive for apnea. There were no significant differences in the final QIDS scores between OSA and non-OSA patients in any of the 4 groups.

Patients with OSA were on a significantly higher number of psychotropic medications (3.2 [±1.6] vs 2.4 [±1.3]; P < .01). This was also true for many of the patient subgroups: those between age 45 and 64 (3.3 vs 2.5; P < .012), those who were overweight (3.2 vs 2.2; P < .01), and those who were obese (3.2 vs 2.3; P < .03).

There were 3 positive OSA cases among 83 patients under age 45 (3.6 %), while 12% of the 197 patients between age 45 and 64 were positive for OSA, and 12% of the 50 patients over age 65 were positive for sleep apnea. When compared with the general population studies by Bixler et al, the patients in this study had a significantly higher rate of apnea in all age groups, except for men age <45 and men age ≥65 (see TABLE). These 2 groups, however, had relatively small sample sizes (27 and 16, respectively), which would make detection of a statistically significant difference difficult. Both populations showed a similar pattern in their age distribution, though, with the incidence in men peaking in middle age and then dropping off, whereas the peak incidence in women was later in life.


Obstructive sleep apnea—Comparison with general population studies

Gender Group Frequency in
current sample
Frequency Bixler2,3
χ2 P value (χ2) P value (binomial test)
Age (years)
Male <45 3.7% (1/27) 1.2% 1.43 .23 .378
45 to 64 15.4% (10/65) 4.7% 16.6 .0001 .0001
≥65 6.3% (1/16) 1.7% 1.98 .16 .24
Female <45 3.3% (2/60) 0.7% 5.99 .014 .047
45 to 64 10.2% (13/128) 1.1% 96.5 10-23 10-22
≥65 14.7% (5/34) 3.1% 15.2 .0001 .001
Male <31.1 8.2% (5/61) 2.0% 12.0 .0006 .0014
>31.1 21% (5/24) 13.8% 1.0 .32 .2
Female <32.3 7.2% (10/139) 0.4% 161 10-36 10-32
>32.3 20% (7/35) 4.8% 12.3 .0005 .001
BMI: body mass index.


This is the first published report of the prevalence of OSA in a large sample of outpatients in a private psychiatric practice. This study has the obvious limitation of being a retrospective chart review, in which 11 out of the 32 identified patients with OSA were included based on self-report of CPAP machine use without a polysomnogram available to independently confirm the diagnosis. It is also possible that some patients have the diagnosis of OSA, but this was missed by the interviewer or the reviewer of the chart, or it was not documented in the chart. Even with this likely underreporting, the 9.7% prevalence of OSA among psychiatric outpatients is larger than that reported for the general population. The true prevalence rate would likely be even higher if all psychiatric outpatients could have a sleep study. The cost and convenience of performing a sleep study limit the feasibility of this approach. Widespread use of the recently developed home screening devices will likely make it easier to identify psychiatric outpatients with OSA. The frequency of OSA in the patients age >65 was 12%, which is lower than the 24% reported by Ancoli-Israel et al8 when they used routine polysomnograms but higher than the prevalence reported by Bixler et al for their subjects age >65 with AHIs >5 and daytime symptoms.2,3

The final QIDS score of OSA patients remained higher than that of non-OSA patients, but not to a statistically significant degree, although the OSA patients took a larger number of medications in a more aggressive attempt to relieve depression. Late insomnia, low energy, and decreased general interest are frequently reported symptoms with OSA. Not surprisingly, they were significantly higher in our dually diagnosed patient sample as well. Overall, the worst QIDS scores were for patients age <45. As suggested by Bixler et al,2 sleep apnea in this age group may be more severe, given its earlier onset than in older patients, similar to earlier onset diabetes or hypertension. This group may also report sleep disruption at a higher rate due to more intolerance of sleep disruption or more interference with daily function.

Attention to sleep symptoms even in remitted depression and a higher suspicion index for OSA in psychiatric outpatients should lead to better outcomes. More aggressive treatment of depression in our OSA patients, as reflected in a higher number of medications taken, reduced their QIDS score to one similar to non-OSA patients.

Also consistent with the literature, there were higher rates of sleep apnea among overweight and obese patients. As seen in the TABLE, the frequency of OSA in our patients was at least 3 times that of a matching general population age and BMI groups. Older patients and those with a higher BMI needed more medications to relieve their depression. They responded less well to medications than did patients without sleep apnea, consistent with the notion that comorbidities increase treatment resistance.


OSA is a significant comorbidity in psychiatric outpatients, especially in older and heavier patients. Identification of this comorbid condition will likely result in better treatment outcomes through weight loss advice, the use of CPAP machines, and more aggressive pharmacotherapy.

DISCLOSURES: Dr. Nasr reports that he is on the speakers bureau of Bristol-Myers Squibb, Forest Pharmaceuticals, GlaxoSmithKline, Eli Lilly and Company, Novartis, Pfizer Inc, and Takeda. Mr. Wendt and Ms. Kora report no financial relationship with any company whose products are mentioned in this article or with manufacturers of competing products.


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CORRESPONDENCE: Suhayl Nasr, MD, 2814 South Franklin Street, Michigan City, IN 46360 USA E-MAIL: nasrpsych@sbcglobal.net