Abstract
Study Objectives:
To determine the short-term positive airway pressure (PAP) adherence rates and to identify non–mask-related risk factors associated with 30-day nonadherence to PAP in a population of veterans with obstructive sleep apnea (OSA) and posttraumatic stress disorder (PTSD).
Design:
A retrospective study.
Settings:
A Veterans Affairs hospital.
Patients:
One hundred forty-eight PTSD veterans newly diagnosed with OSA and a control group of OSA without PTSD matched for age, gender, BMI, and severity of OSA.
Interventions:
N/A
Measurements and Results:
At 30-day follow-up, adherence to PAP was significantly lower in the PTSD group compared to the control group (41% versus 70%, respectively; P < 0.001). Veterans with adequate PAP adherence were more likely to experience sleepiness at baseline compared to nonadherent subjects (ESS 14.4 ± 5.3 versus 12.3 ± 5.9, respectively; P = 0.04). Nightmares were more frequently reported in those who were PAP nonadherent (P = 0.002). Mask discomfort, claustrophobia, and air hunger were the reported reasons for PAP nonadherence in the PTSD group.
Conclusion:
PAP usage and adherence were lower in PTSD veterans with OSA than veterans without PTSD. Excessive sleepiness predicted PAP adherence while frequent nightmares were correlated with poor adherence to PAP therapy.
Citation:
El-Solh AA; Ayyar L; Akinnusi M; Relia S; Akinnusi O. Positive airway pressure adherence in veterans with posttraumatic stress disorder. SLEEP 2010;33(11):1495-1500.
Keywords: PTSD, adherence, CPAP, obstructive sleep apnea
ABOUT ONE IN SIX US VETERANS IS ESTIMATED TO BE AFFECTED WITH POSTTRAUMATIC STRESS DISORDER (PTSD).1,2 PTSD IS A DEBILITATING ANXIETY disorder reported in 25% to 30% of individuals experiencing a traumatic event.3 Veterans with PTSD present with constellations of symptoms such as intrusive recollections and avoidance of trauma-related stimuli.4 Recurrent distressing dreams and nightmares are accompanied by repeated awakenings and difficulty falling asleep and staying asleep.
Accruing evidence suggests that veterans with PTSD are at higher risk for sleep disordered breathing than non-veterans.5 The literature has long debated whether sleep disturbances predispose to the development of PTSD or whether symptoms of PTSD lead to exacerbation of sleep difficulties. Regardless of the initial insult, there is strong evidence to suggest that untreated sleep related disorders accentuate PTSD symptoms.6 In the study of Krakow and colleagues,7 treatment of behavioral manifestations of PTSD was more likely to be successful when comorbid sleep disordered breathing (SDB) was adequately treated. However, 65% of such patients discontinued treatment prematurely for unreported reasons.7 To date, effective treatment of SDB is typically achieved with positive airway pressure (PAP) therapy.
Adherence to PAP therapy is a major challenge to successful treatment of SDB. Despite its efficacy in improving daytime somnolence, quality of life, and probably in alleviating cardiovascular risk factors,8,9 compliance with PAP therapy is suboptimal. Using data from a comprehensive PAP program at our center, the aims of the study were: (1) to determine the short-term PAP adherence rate in a veteran population with obstructive sleep apnea (OSA) and PTSD and (2) to identify non–mask-related risk factors associated with nonadherence to PAP in this population.
METHODS
Study Population
We retrospectively reviewed the VA Computerized Patient Record System of consecutive veterans with PTSD who were referred to the Western New York Healthcare System sleep disorder clinics between January 2005 and June 2009 for evaluation and treatment of obstructive sleep apnea. PTSD diagnosis was based on DSM IV criteria,10 as documented by the attending psychiatrists responsible for the patients' psychiatric care. In compliance with federal regulations, permission to perform the study was granted by the VA Institutional Review Board. We recorded the clinical history, demographics, clinical diagnoses, Epworth Sleepiness Scale (ESS) scores, polysomnographic data, and medications. We categorized the medications that were prescribed into the following groups: (a) benzodiazepines, (b) antidepressants, (c) non-benzodiazepine hypnotics, (d) opiates, and (e) others. Exclusion criteria included the diagnosis of psychosis or paranoia, and prior surgical treatment for OSA. A control group of veterans matched for age (± 5 years), BMI (± 2 kg/m2), and severity of OSA (mild, moderate, or severe) was also identified.
Polysomnogram
Standard polysomnographic techniques were used. Data from the electrooculogram, electroencephalogram, electrocardiogram, electromyogram, airflow measurement, and pulse oximeter were recorded with Sandman digital recording equipment (Tyco, Ottawa, Canada). The apnea-hypopnea index (AHI) was calculated from the polysomnographic data, using widely accepted criteria.11 Apneas were defined as cessation of airflow ≥ 10 s, and hypopneas were defined as a decrease in airflow ≥ 10 s accompanied by an oxyhemoglobin desaturation ≥ 4%. The diagnosis of obstructive sleep apnea was made if the sum of the obstructive apneas and hypopneas per hour was ≥ 5. Severity of OSA was judged from AHI data and graded as mild OSA (5 ≤ AHI < 15/hr), moderate OSA (15 ≤ AHI < 30/hr), and severe OSA (AHI > 30/hr).
Follow-up
Following confirmation of OSA, veterans were interviewed by a sleep specialist to determine the appropriate therapy. For those who were prescribed PAP, a respiratory nurse provided education about the basic operation and care of the PAP device and the mask. An educational brochure on OSA and PAP treatment was given to each patient during the education session. The nurse would then select and fit a comfortable PAP mask from a wide range of choices. In each instance, we documented the specialist's treatment recommendations for each patient, including modality of positive airway pressure, type of mask prescribed, and adherence with PAP therapy. We routinely recommended 1-month (30 ± 7 days) follow-up at our center. Patients were also provided telephone numbers to the respiratory therapy department to help troubleshoot treatment issues. We searched the medical records for any follow-up visits or telephone encounters (which are routinely recorded) for one month following treatment. Problems with the mask interface were classified into complaints of too much pressure, claustrophobia, nasal congestion, air hunger, head gear problems, and mask discomfort.
PAP Adherence
Adherence to PAP therapy was measured by Respironics Smart Cards (Respironics, Inc., Murrysville, PA). Adequate adherence was defined as PAP usage > 4 h/ night for 70% of days.12
Statistical Analysis
The means and standard deviations (SDs) of continuous variables were compared using the Student 2-tailed t-test. Nonnormally distributed variables were compared using the Wilcoxon rank-sum test. Ordinal and binary variables were compared using a χ2 test. A stepwise logistic regression was performed to identify independent factors associated with PAP adherence (dependent variable) in patients with PTSD. Only those variables that produced a P-value < 0.15 in univariate analysis were entered into stepwise regression model. Collinearity was evaluated by the variance inflation factor. P values ≤ 0.05 (2-tailed) were considered statistically significant. All analyses were performed with statistical software (SAS release 8.1; SAS Institute; Cary, NC).
RESULTS
Baseline Assessments
During the study period 148 veterans with PTSD were diagnosed with OSA based on diagnostic polysomnography. The baseline demographics and sleep study features of the study population and the control group are shown in Table 1. The 2 groups were not different in their major demographic variables or underlying medical conditions. Depression and nightmares were more prevalent, however, in veterans with PTSD than the control group (54% and 73% versus 13% and 8%, respectively; P < 0.001). Similarly, alcohol and substance abuse were more frequently present in PTSD subjects than controls (P < 0.001). Only one veteran of the control group had documented history of depression. Eight of 9 veterans without PTSD who were receiving antidepressants were being treated for insomnia. None of these had PTSD.
Table 1.
Characteristics of study population with obstructive sleep apnea
| PTSD (n = 148) | Control (n = 148) | P value | |
|---|---|---|---|
| Age, years | 59.7 ± 7.9 | 61.5 ± 8.3 | 0.21 |
| Gender (M/F) | 148 / 0 | 148 / 0 | 1.0 |
| Race | 0.21 | ||
| Caucasians, n (%) | 132 (89) | 126 (85) | |
| African American, n (%) | 10 (7) | 18 (12) | |
| Hispanic, n (%) | 4 (3) | 2 (1) | |
| BMI,kg/m2 | 35.4 ± 6.9 | 34.9 ± 6.3 | 0.59 |
| FEV1, % | 73.2 ± 18.8 | 75.6 ± 20.4 | 0.60 |
| Comorbid diseases | |||
| Hypertension | 111 (75) | 114 (77) | 0.79 |
| Cardiac diseases | 35 (24) | 46 (32) | 0.19 |
| Diabetes mellitus | 82 (55) | 70 (47) | 0.20 |
| Depression | 72 (49) | 1 (0.6) | < 0.001 |
| Alcohol/ substance abuse | 24 (16) | 2 (1) | < 0.001 |
| Sleep indices at baseline | |||
| ESS | 13.0 ± 5.7 | 14.2 ± 6.4 | 0.34 |
| Sleep efficiency, % | 59.5 ± 19.9 | 70.8 ± 17.7 | 0.004 |
| Arousals/h | 18.7 ± 21.5 | 13.1 ± 15.2 | 0.02 |
| Oxygen saturation, % | |||
| Average | 92 ± 2 | 92 ± 3 | 0.9 |
| Lowest | 80 ± 6 | 78 ± 9 | 0.17 |
| AHI/h | 34.5 ± 25.1 | 39.2 ± 27.3 | 0.67 |
| Mild OSA, n (%) | 46 (31) | 35 (24) | 0.19 |
| Moderate OSA, n (%) | 32 (22) | 33 (23) | 1.0 |
| Severe OSA, n (%) | 70 (47) | 75 (51) | 0.64 |
| Treatment modality of OSA | |||
| Fixed CPAP, n (%) | 87 (59) | 94 (64) | 0.47 |
| Autotitrating PAP, n (%) | 57 (38) | 47 (32) | 0.27 |
| Bilevel PAP, n (%) | 4 (3) | 7 (5) | 0.54 |
mean ± SEM
Forty-two percent of the study population had a split-night study, with no difference between the PTSD and the control group (41% and 43%, respectively). While daytime sleepiness and severity of OSA were comparable in both cohorts, patients with PTSD had reduced sleep efficiency and higher frequency of arousals than controls. All veterans received positive airway pressure with no significant difference in the PAP modalities prescribed between the 2 groups.
PAP Adherence
At one-month follow-up, 6 veterans with PTSD and one control failed to return to the clinic. Adherence to PAP was significantly lower in the PTSD group than the controls (Figure 1). In PAP adherent PTSD veterans, the ESS fell from 14.4 ± 5.3 at baseline to 6.2 ± 4.7 (P < 0.001). The average time used per night and the percentage of nights with > 4 h of use were 269.6 ± 122.8 min and 46.6% ± 32.8% for veterans with PTSD, and 314.7 ± 131.4 min and 58.3% ± 31.8% for those without PTSD, respectively; (P < 0.001 and P < 0.001). Yet, the average PAP pressure was similar in both groups at 7.1 ± 2.5 and 7.6 ± 2.8 cm H2O, respectively (P = 0.62).
Figure 1.
Positive airway pressure adherence rates in veterans with PTSD and veterans without PTSD at 30-day follow-up.
Table 2 shows the characteristics of veterans with PTSD who were adherent to PAP compared to those who were nonadherent. In univariate analysis, veterans with adequate PAP adherence were more likely to experience sleepiness at baseline than those who were nonadherent (ESS 14.4 ± 5.3 versus 12.3 ± 5.9, respectively; P = 0.04). Nightmares were more frequently reported in those who were PAP nonadherent (P = 0.002). Age, BMI, marital status, substance abuse, severity of sleep apnea, PAP modality, and PAP pressure were not determinants of PAP adherence. There was also no difference in terms of antidepressant or hypnotic use between PAP adherent and PAP nonadherent PTSD subjects. Only opiates were more likely to be prescribed for veterans with PTSD, but the difference did not reach statistical significance.
Table 2.
Comparison between PAP adherent and nonadherent veterans with PTSD at 30-day follow-up
| PAP adherent (n = 60) | PAP nonadherent (n = 82) | P value | |
|---|---|---|---|
| Age, years | 58.9 ± 7.4 | 60.3 ± 8.5 | 0.29 |
| Gender (M/F) | 60 / 0 | 82 / 0 | 1.0 |
| BMI, kg/m2 | 36.0 ± 7.2 | 34.9 ± 6.8 | 0.36 |
| Married, n (%) | 48 (80) | 61 (74) | 0.56 |
| Employed, n (%) | 13 (22) | 13 (16) | 0.54 |
| Educational level | 0.51 | ||
| High school | 16 (27) | 32 (39) | |
| Associate degree | 14 (23) | 12 (15) | |
| Bachelor degree | 4 (7) | 4 (5) | |
| Doctorate degree | 7 (11) | 8 (10) | |
| Other | 19 (32) | 26 (31) | |
| Psychiatric disorders | |||
| Depression, n (%) | 29 (48) | 43 (52) | 0.75 |
| Chronic pain, n (%) | 11 (18) | 23 (28) | 0.24 |
| Insomnia, n (%) | 18 (30) | 31 (38) | 0.43 |
| Nightmares, n (%) | 17 (28) | 46 (56) | 0.002 |
| Alcohol/ substance abuse, n (%) | 7 (12) | 17 (21) | 0.23 |
| Medications | |||
| Antidepressants, n (%) | 48 (80) | 60 (73) | 0.46 |
| Benzodiazepines, n (%) | 13 (22) | 25 (30) | 0.32 |
| Non-benzodiazepine hypnotics, n (%) | 5 (8) | 10 (12) | 0.64 |
| Opiates, n (%) | 8 (13) | 21 (26) | 0.11 |
| Sleep indices at baseline | |||
| ESS | 14.4 ± 5.3 | 12.1 ± 5.9 | 0.01 |
| Sleep efficiency, % | 73.1 ± 15.3 | 69.3 ± 19.2 | 0.09 |
| Arousals/h | 16.7 ± 15.2 | 20.9 ± 18.7 | 0.04 |
| Oxygen saturation, % | |||
| Average | 92 ± 3 | 92 ± 2 | 0.65 |
| Lowest | 80 ± 6 | 81 ± 7 | 0.46 |
| AHI/h | 35.3 ± 22.1 | 33.5 ± 23.0 | 0.67 |
| Mild OSA, n (%) | 19 (32) | 21 (26) | 0.54 |
| Moderate OSA, n (%) | 11 (18) | 18 (22) | 0.75 |
| Severe OSA, n (%) | 30 (50) | 43 (52) | 0.9 |
| Mean oxygen saturation, % | 92.45 ± 2.9 | 92.2 ± 2.8 | 0.65 |
| PAP modality | |||
| Fixed CPAP, n (%) | 39 (65) | 45 (55) | 0.30 |
| Autotitrating PAP, n (%) | 19 (32) | 35 (43) | 0.24 |
| Bilevel PAP, n (%) | 2 (3) | 2 (2) | 0.85 |
| Mask type | |||
| Nasal mask, n (%) | 42 (70) | 54 (66) | 0.73 |
| Face mask, n (%) | 14 (23) | 20 (24) | 0.96 |
| Nasal pillow, n (%) | 4 (7) | 8 (10) | 0.73 |
| PAP usage | |||
| Average use per night, min | 422 ± 76 | 226 ± 94 | < 0.001 |
| % use > 4 h per day, % | 87.4 ± 9.7 | 31.1 ± 21.4 | < 0.001 |
| Average pressure, cm H2O | 8.1 ± 2.5 | 7.3 ± 1.9 | 0.23 |
mean ± SEM
Problems Related to PAP Adherence
Common problems related to PAP nonadherence are shown in Table 3. Mask discomfort was the primary reason reported for nonadherence in both the PTSD and the control group. Similarly, air hunger and high pressure were equally responsible for nonadherence in both groups. Claustrophobia was more frequently reported in PTSD than non PTSD veterans; however, the difference was not statistically significant (P = 0.1). Other less frequent causes cited included nasal dryness, air leaks, and epistaxis.
Table 3.
Reported reasons for nonadherence to PAP therapy at 30-day follow-up
| Problems (n, %) | Control (n = 43) | PTSD (n = 82) | P value |
|---|---|---|---|
| Mask discomfort | 20 (47) | 27 (33) | 0.19 |
| High pressure | 7 (16) | 18 (10) | 0.43 |
| Air hunger | 3 (7) | 12 (15) | 0.33 |
| Claustrophobia | 4 (9) | 19 (23) | 0.10 |
| Others | 9 (21) | 16 (19) | 0.96 |
Predictors of PAP adherence in PTSD
Four variables (opiates use, nightmares, arousals, and ESS) were entered into a stepwise logistic regression. Both nightmares (P = 0.001) and ESS (P = 0.028) were found to be independent predictors of PAP nonadherence (Table 4).
Table 4.
Non–mask-related predictors of PAP adherence in veterans with PTSD
| Variable | Unadjusted OR | 95% CI | Adjusted OR | 95% CI |
|---|---|---|---|---|
| ESS | 1.07 | 1.00-1.15 | 1.08 | 1.01-1.17 |
| Nightmares | 0.31 | 0.15-0.63 | 0.23 | 0.10-0.53 |
ESS refers to Epworth Sleepiness Scale; OR, Odds ratio; CI, Confidence Interval
DISCUSSION
This is the largest study, to our knowledge, to assess short-term PAP adherence in veterans with PTSD. The results of this investigation indicate a high rate of PAP nonadherence for veterans with PTSD when compared with the general population matched for age, gender, and severity of obstructive sleep apnea. The presence of nightmares was highly predictive of lack of PAP adherence, while excessive sleepiness was an indicator of adherence to PAP therapy.
The association between PTSD and OSA has been recognized for several years.13–15 PAP therapy has appeared to confer a favorable response in the majority of recipients with PTSD, while nonadherence might promote greater nightmare recall through frequent awakenings and arousals. In 1998, Youakim and colleagues13 reported the first case of a Vietnam veteran with PTSD and severe OSA whose PTSD symptoms abated after treatment with PAP. Consistent with the findings of Youakim et al.,13 Krakow and coworkers contacted 23 chronic nightmare sufferers, 15 of whom had PTSD and SDB. Nine had 75% improvement in their PTSD symptoms after PAP therapy, while four of the six who refused or did not tolerate positive airway pressure had worsening symptoms.15 We need to point out that the presence of PTSD in the latter study was determined by clinician interview rather than a psychometrically validated instrument, and the adherence data on PAP was obtained from a telephone survey rather than smart cards. Despite these encouraging reports, adherence to PAP in veterans with PTSD in our study was significantly lower than a matched control group.
The determinants of PAP adherence remain poorly understood. A number of studies have identified significant relationships between several physical and psychological variables and PAP use. However, these specific predictors have not been consistently replicated. Like others,16–18 we found no correlation between age, gender, marital status, or employment status in PTSD subjects and PAP adherence. Some19,20 have reported positive correlation between initial BMI and adherence, but in line with other investigations,17,21 our data found that neither BMI nor forced expiratory volume in 1 second was associated with machine use.
Disease severity has been shown to have an inconsistent relationship with PAP adherence. In a prospective long-term study, snoring and AHI showed significant correlation with higher average hours of PAP use per day at both 1 month and 3 months.22 Similarly, Hui and colleagues23 identified baseline AHI as the only independent predictor of PAP compliance. In contrast, we found no independent association between any of the measurements of nocturnal respiratory disturbance and PAP use in veterans with PTSD. Most investigators were also not able to show any difference between those who were compliant and non-compliant with PAP in baseline AHI and other polysomnographic indices at presentation.12,21,24–27 In a comprehensive review of studies that have examined predictors of adherence to PAP, Engleman and Wild reported that, identified polysomnographic variables collectively explained only 4% to 25% of the variance in PAP use.28
The face mask interface has been reported to invoke flashbacks by some veterans with the face mask likened to a gas mask.29 Our study failed to find any link between the type of mask prescribed and adherence to PAP therapy. There was also no significant difference in the frequency of claustrophobia between the groups of veterans adherent and nonadherent to PAP. Chasens and coworkers30 previously described this association in a cohort of 153 patients with OSA. Participants with poor adherence to PAP had significantly higher claustrophobia scores than more adherent participants. In the present study, early treatment exposure with immediate troubleshooting and follow-up was likely an important factor that led to the lessening of claustrophobic tendencies in veterans with PTSD.
Baseline excessive daytime sleepiness in veterans with PTSD was the only significant sleep factor related to PAP adherence in our study. The association between daytime excessive sleepiness and PAP adherence might be attributed to greater willingness of PTSD subjects with OSA to continue treatment among those who noticed improvement in daytime symptoms. It is plausible that there is a bidirectional relationship with adherence improving symptoms and symptom improvement promoting sustained adherence to PAP. We should point out that there is a knowledge gap of how much a patient's ESS score must change with treatment to be considered clinically significant. Determining clinical significance generally requires well-constructed and well-described normative data. These data are currently lacking for the ESS.
By the same token, the feedback loop between symptom improvement and PAP adherence may be attenuated by the presence of depression. Depression, a major comorbidity of PTSD, may diminish the subjective benefits of PAP, thereby depriving the patient of one of the most important reasons to maintain treatment. Depression may also directly impede the use of PAP, because it is associated with reduced adherence to medical treatment regimens in many different patient populations. In agreement with Wells and coworkers,31 the presence of depression did not predict PAP nonadherence; however, we could not determine from reviewing the medical records whether all symptoms of depression were controlled. Since depressive symptoms and self-reported measures of daytime sleepiness both improve post PAP treatment,32 systematic assessment of depressive symptoms in PTSD ought to be part of the evaluation process for those who are nonadherent to PAP.
In the present study, nightmares were found to be indicative of PAP nonadherence. Frequent awakenings with panic or anxiety attacks following nightmares might have contributed to the poor CPAP compliance in subjects with PTSD who were not willing to put the mask back on. Interestingly, the total sleep time of patients with PTSD was statistically shorter than the control group, which may indicate prolonged wakefulness following nightmares. Furthermore, PSG analysis of PAP nonadherent subjects reflected a higher frequency of fragmented sleep at baseline with frequent arousals compared to PAP adherent veterans. Several theories have been proposed to link these dreams to an abnormal REM mechanism4,33 but the repetitive nature of these events occurring earlier in the sleep cycle has led some to reconsider nightmares as both a REM and NREM phenomenon.34,35 Disruptions of REM sleep caused by these arousals might have led to increased recall of dreams resulting in an anxiogenic effect. Hence, restoration of sleep architecture in REM and NREM sleep may be the key to improvement in PTSD symptoms. One case report suggested that PAP therapy led to few disruptions of REM sleep and reduction in the frequency of nightmares.13 While this may be the case in the PAP adherent group, other therapeutic interventions may be needed to restore sleep homeostasis in the nonadherent patients.
Our study has several limitations. The retrospective design of the study may allow introduction of selection bias. However, we obtained data on all 148 consecutive PTSD patients who met the selection criteria. Second, our population was predominantly composed of Caucasian subjects and may not be generalizable to all populations. Third, we could not verify that all control subjects were screened for PTSD, which could have resulted in misclassification of control cases. Fourth, we followed the patients for only 30 days. However, earlier studies demonstrated that long-term adherence to PAP therapy may be comparable to that at 1 month.27,36 Fifth, the variables evaluated in this study explain only a small portion of the variance in PAP adherence. Factors such as patient experience on the PAP titration night, patient support, partner- versus self-referral, self-efficacy, and risk perception measured one week after participants began using PAP37,38 may also be important in continued adherence to this therapeutic modality, but were not evaluated in this study.
The importance of further research focusing on the intensity and treatment of nightmares in PTSD patients with OSA is underscored by the emerging knowledge on cardiovascular complications of OSA and poor compliance with CPAP therapy. Imagery rehearsal therapy for nightmares has been effective in improving sleep quality and reducing maladaptive thinking patterns.39 Pharmacotherapy has also its limited success in ameliorating PTSD severity.40 Whether behavioral therapy alone or in combination with drug therapy can improve CPAP compliance in these patients deserves exploration in prospective studies.
In summary, this study has shown a lower PAP adherence among PTSD veterans newly diagnosed with OSA compared to non PTSD veterans with OSA. The independent factor predicting better PAP adherence at 30-day follow-up was excessive sleepiness at baseline, while nightmares were predictive of PAP nonadherence.
DISCLOSURE STATEMENT
This was not an industry supported study. The authors have indicated no financial conflicts of interest.
Footnotes
A commentary on this article appears in this issue on page 1435.
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