Sleep Medicine 11 (2010) 772–776
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Original Article
Sleep maintenance insomnia complaints predict poor CPAP adherence: A clinical case series Emerson M. Wickwire a,b,*, Michael T. Smith b, Sandra Birnbaum b, Nancy A. Collop c a
Center for Sleep Disorders, Pulmonary Disease and Critical Care Associates, Columbia, MD, USA Behavioral Sleep Medicine Program, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA c Johns Hopkins Hospital Sleep Disorders Center, Division of Pulmonary and Critical Care, Johns Hopkins School of Medicine, Baltimore, MD, USA b
a r t i c l e
i n f o
Article history: Received 2 September 2009 Received in revised form 10 March 2010 Accepted 31 March 2010 Available online 31 July 2010 Keywords: Sleep Insomnia Apnea CPAP Adherence Interdisciplinary Comprehensive sleep medicine
a b s t r a c t Background: Although CPAP is a highly efficacious treatment for obstructive sleep apnea (OSA), low adherence presents a significant challenge for sleep medicine clinicians. The present study aimed to evaluate the relationship between insomnia symptoms and CPAP use. We hypothesized that pre-treatment insomnia complaints would be associated with poorer CPAP adherence at clinical follow-up. Methods: This was a retrospective chart review of 232 patients (56.5% men, mean age = 53.6 ± 12.4 years) newly diagnosed with OSA (mean AHI = 41.8 ± 27.7) and prescribed CPAP in the Johns Hopkins Sleep Disorder Center. Difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening were measured via three self-report items. CPAP use was measured via objective electronic monitoring cards. Results: Thirty-seven percent of the sample reported at least one frequent insomnia complaint, with 23.7% reporting difficulty maintaining sleep, 20.6% reporting early morning awakening and 16.6% reporting difficulty initiating sleep. After controlling for age and gender, sleep maintenance insomnia displayed a statistically significant negative relationship with average nightly minutes of CPAP use (p < .05) as well as adherence status as defined by the Centers for Medicaid and Medicare Services (p < .02). Conclusions: To our knowledge, these are the first empirical data to document that insomnia can be a risk factor for poorer CPAP adherence. Identifying and reducing insomnia complaints among patients prescribed CPAP may be a straightforward and cost-effective way to increase CPAP adherence. Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction Insomnia and sleep-disordered breathing are the two most common sleep disorders seen in clinical practice, and each has been independently associated with increased risk for negative health outcomes and negative daytime sequelae [1,2]. Historically, the two disorders were conceptualized as either orthogonal or insomnia was considered a symptom of sleep-disordered breathing (SDB). More recent perspectives reflect growing recognition that insomnia and SDB frequently co-exist as distinct disease entities requiring independent treatment [3]. Indeed, evidence from clinical [4–9], research [10,11], and population-based [12] samples suggests the disorders frequently co-occur, with at least two studies reporting that over half of patients undergoing evaluation for obstructive sleep apnea (OSA) report at least one insomnia complaint [4,8]. Further, the consequences of the disorders appear to be additive, with patients who suffer both conditions experiencing greater daytime impairment, including more psychiatric distress
* Corresponding author. Address: Center for Sleep Disorders, Pulmonary Disease and Critical Care Associates, 10710 Charter Drive, Suite 310, Columbia, MD 21044, USA. Tel.: +1 (410) 997 5944; fax: +1 (410) 997 1720. E-mail address:
[email protected] (E.M. Wickwire). 1389-9457/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2010.03.012
[9], sleepiness [12,13], and slower psychomotor reaction times [14], relative to patients with only one disorder. Patients with both disorders report worse subjective sleep [9] and demonstrate significantly longer sleep latency, less total sleep time, and lower sleep efficiency than patients with apnea alone [7]. In addition to these sleep disturbances, patients with both insomnia and sleep apnea also demonstrate poorer neurocognitive function, greater functional impairment, and more daytime sleepiness relative to patients with apnea alone [14]. In one large scale study, suspected SDB and insomnia independently predicted daytime sleepiness [12]. As a result of this expanding awareness, sleep medicine clinicians and researchers have become increasingly interested in the interaction between the two disorders. Although no clear practice guidelines yet exist for the treatment of comorbid insomnia and sleep-disordered breathing, data are beginning to emerge regarding the treatment of the two disorders when they co-occur. Results consistently suggest that patients who receive treatment for both insomnia and SDB demonstrate greater improvement than patients treated for either condition alone [15–17]. Further, failure to treat either underlying disorder may compromise treatment of the other. For example, among OSA patients treated with an oral mandibular repositioning device, only complaints of insomnia predicted non-improvement from treatment
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[18]. Similarly, clinical experience suggests that complaints of difficulty initiating or maintaining sleep may be related to difficulty adhering to CPAP, the most effective and commonly prescribed treatment for obstructive sleep apnea [19]. Clinical experience suggests that patients with insomnia often report anxiety that the CPAP apparatus will further disrupt sleep and may be prone to discontinue CPAP therapy during episodes of insomnia. In light of the known effectiveness of CPAP and the availability of effective treatments for insomnia, the potential role of insomnia complaints in CPAP use is paramount. However, to our knowledge no empirical study to date has evaluated the effect of insomnia complaints on subsequent CPAP adherence. The primary purpose of the current project was to explore the relationships between insomnia complaints and CPAP adherence in a sample of patients treated for OSA. Although this study was primarily exploratory in nature, we hypothesized that pretreatment insomnia complaints would be associated with less CPAP use.
2. Methods 2.1. Participants Participant data for these analyses were extracted by chart review of 232 consecutive patients (56.5% men, mean age= 53.6±12.4 years, mean BMI=34.4±7.7) diagnosed with obstructive sleep apnea (mean AHI=41.8±27.7) who were prescribed CPAP (mean pressure=9.7±2.8cm/H20) at the Johns Hopkins Hospital Sleep Disorder Center (JHHSDC). Sample characteristics are presented in Table 1. Participants reported membership in the following ethnic categories: Caucasian (53.9%); African-American (28.3%); Asian (11.2%); and other (6.3%). A majority (70.2%) of patients attended at least some college, with 19.8% being college graduates and 23.7% holding advanced degrees. Most participants (57.8%) were married, while a quarter (25.4%) were single, and 17.1% were divorced, widowed, or separated. Inclusion criteria included age over 18 years, new diagnosis of obstructive sleep apnea with prescription for CPAP, and availability of a minimum of 28 days of CPAP adherence data. Because the purpose of this study was to generate hypotheses with broad generalizability, no additional exclusion criteria were applied.
Table 1 Demographic characteristics of sample.
Age BMI
M ± SD 53.6 ± 12.4 years 34.4 ± 7.7 %
Gender Male Female
56.5 43.5
Ethnicity Caucasian African-American Asian Other
53.9 28.3 11.2 6.5
Education Less than grade 12 High school diploma or equivalent Some college College graduate Advanced degree
9.5 19.8 26.7 19.8 23.7
Marital status Married Single Divorced Widowed Separated
57.8 25.4 7.8 5.2 4.3
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2.2. Procedures This was a retrospective chart review study. All patients underwent CPAP titration and were subsequently seen for follow-up visits between July 2004 and May 2007 at the JHHSDC. Prior to their CPAP titration, patients completed questionnaires assessing demographic characteristics, medical history, and insomnia symptoms as part of routine clinical practice. Approval for this research was obtained from the institutional research board at the Johns Hopkins School of Medicine following procedures in accordance with the declaration of Helsinki. 2.3. Measures 2.3.1. Insomnia Complaints As part of a standard intake questionnaire, insomnia symptoms were assessed using 3 items measuring complaints of difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening within the past month. All responses were scored on a 0-5 scale (never, rarely, sometimes, often, usually, and always). 2.3.2. Sleep scoring Polysomnography was performed using electrodes and sensors applied according to standard procedure using the following montage: 2 EEG (C3-M2, O2-M1), LOC EOG, ROC EOG, chin EMG, right leg EMG, left leg EMG, EKG (Lead II), nasal cannula pressure transducer, airflow (thermister), respiratory impedence plethysmography, oximetry, and video monitoring. Sleep scoring was conducted by a registered polysomnographic technician and reviewed by a sleep board-certified physician. Sleep staging was scored according to R&K [20], and respiratory events were scored as follows: apnea – 90% reduction in airflow for at least 10 seconds; hypopnea – 30-90% reduction in airflow accompanied by an EEG arousal and/or 4% fall in oxygen saturation. 2.3.3. CPAP titration All patients underwent a CPAP titration as either part of a split or full-night protocol using the same monitoring montage described above. CPAP was incrementally adjusted to eliminate apneas, hypopneas, flow limitation, and snoring with the goal being an AHI < 5. 2.3.4. CPAP adherence As part of routine clinical practice in the JHHSDC, all patients prescribed CPAP are seen for follow-up visits and instructed to bring their electronic monitoring cards to evaluate objective CPAP use. At the time of data collection, a majority of patients prescribed CPAP in the JHHSDC received a Respironics (Murraysville, PA) machine, and this was the case for 94.0% of participants in the current study. The remaining participants received a ResMed (San Diego, CA) machine. Once prescribed CPAP, patients are typically scheduled for follow-up visits in our clinic within 30 days. In order to maximize the generalizability of our findings, we included all consecutive follow-up patients seen within one year (365 days) of CPAP titration. All patients provided a minimum of 28 days of data (mean=135.4±85.8 days). 3. Results 3.1. Analytic Plan Prior to evaluating the predictive relationships between insomnia complaints and CPAP use, it was first necessary to evaluate the relationship between OSA disease severity (AHI) and insomnia complaints. AHI was uncorrelated with all 3 insomnia items
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(r’s ranged from .01 to .04, all p’s>.3), but complaints of sleep maintenance insomnia and early morning awakening were highly correlated with each other (r=.58, p70% of nights with minimum 4h use), a series of unconditional logistic regression analyses were performed. Patients were placed in one of two adherence categories: compliant or non-compliant. This binary dependent variable was regressed onto the independent variables of insomnia complaint, age, and gender. Complaints of difficulty maintaining sleep displayed a statistically significant negative relationship (p=.02) to the dependent variable. For each one-point increase on the sleep maintenance insomnia scale, the patient was .81 times less likely to meet the CMS criterion for CPAP adherence. Results are presented in Table 3.
Table 2 Summary of simultaneous multiple linear regression analyses predicting average nightly CPAP use (N = 232). B
SE B
p
Constant Age Gender Difficulty initiating sleep
301.82 .30 10.54 1.91
50.61 .79 19.86 7.27
.00 .71 .60 .79
Constant Age Gender Difficulty maintaining sleep
331.55 .46 10.42 12.05
50.61 .76 19.22 6.14
.00 .55 .59 .05
Constant Age Gender Early morning awakening
311.60 .57 12.73 .11
49.88 .77 19.45 6.81
.00 .46 .51 .99
4. Discussion In this case series of OSA patients treated with CPAP and reporting for clinical follow-up, insomnia complaints were frequent. Complaints of sleep maintenance insomnia were associated with poorer objective measures CPAP adherence. Further, symptoms of sleep maintenance insomnia were not associated with the apneahypopnea index. These results suggest that in the current sample, symptoms of maintenance insomnia existed independent of OSA and that the effects of maintenance insomnia on CPAP adherence were not attributable to OSA disease severity. In the current study, the most common insomnia complaint was difficulty maintaining sleep (23.7%) followed by early morning awakening (20.6%) and difficulty initiating sleep (16.6%). Overall, these proportions are consistent with previous literature documenting that difficulty maintaining sleep is the most common insomnia complaint of patients evaluated for obstructive sleep apnea. For example, Chung [4] found 26% of clinic patients evaluated for sleep-disordered breathing (SDB) reported sleep maintenance insomnia, while 19% reported early morning awakening, and only 6% reported difficulty initiating sleep. Although there is no cure for OSA, CPAP therapy is the most effective and most commonly prescribed treatment for the disease. However, many patients struggle to adjust to the treatment, resulting in significant negative health consequences (eg, diabetes, cardiovascular disease, stroke) and enormous societal costs (eg, lost productivity, catastrophic accidents, increased healthcare utilization). In this light improving CPAP adherence is a major public health concern. Beyond relatively straightforward technical issues such as mask fit or even more complex psychological factors such
Table 3 Unconditional logistic regression analyses predicting CMS adherence status.a SE B
Wald
df
p
OR
Constant Age Gender Difficulty initiating sleep
Variable
B .70 .01 .20 .06
.69 .01 .28 .09
1.03 1.58 .54 .36
1 1 1 1
.310 .21 .46 .55
.497 1.01 .82 .95
Constant Age Gender Difficulty maintaining sleep
.16 .01 .17 .22
.70 .01 .28 .09
.05 1.14 .39 5.75
1 1 1 1
.82 .29 .53 .02
.85 1.01 .84 .81
Constant Age Gender Early morning awakening
.64 .01 .20 .06
.71 .01 .27 .10
.81 .69 .50 .42
1 1 1 1
.37 .41 .42 .53
.53 1.00 .83 1.07
a Centers for Medicare and Medicaid Services (CMS) definition of adequate CPAP adherence, i.e., minimum 4 h use on 70% of nights.
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as self-efficacy to use CPAP [21,22], clinical experience suggests that many patients experiencing difficulty adjusting to CPAP ascribe this difficulty to difficulty initiating or maintaining sleep. It is thus surprising that the relationship between insomnia complaints and CPAP adherence has received little research attention. In the current study, difficulty maintaining sleep was consistently associated with less CPAP use as averaged across all nights as well as lower rates of adherence using the 2009 CMS definition of CPAP adherence. One explanation for these findings might be that patients who experience difficulty maintaining sleep might be more likely to wake up and experience frustration at having to wear a CPAP mask and remove the mask as a result. Patients with chronic insomnia are often preoccupied with external factors that might be perceived as a threat to sleep [23], and these beliefs might extend to the CPAP device itself and contribute to poor compliance. However, neither complaints of difficulty initiating sleep nor early morning awakening were associated with CPAP use. The former finding may be explained by the relative OSA severity in our sample. Others have documented an inverse relationship between sleep onset latency and OSA disease severity [5], and it is possible patients in the current study were sleepy enough at bedtime to overcome any perceived discomfort associated with CPAP use. The finding regarding early morning awakening is somewhat more perplexing but may be due to the high overlap between complaints of sleep maintenance insomnia and early morning awakening in our sample. These results highlight a limitation of the current study and the need for comprehensive and reliable assessment of insomnia disorder (eg, [24]) among SDB patients as well as further investigation of the relationships between insomnia subtypes and CPAP use. The current findings also highlight the need for greater understanding of the relationship between pre-treatment, patient-level characteristics and response to CPAP. For example, modifiable psychological factors such as perceptions regarding OSA and CPAP as well as level of daily functioning, subjective distress, perceived costs and benefits of using CPAP, and self-efficacy to use CPAP have been consistently associated with CPAP use [25]. Indeed psychological variables can accurately predict CPAP non-adherers even when measured pre-titration (eg, [26]). At the same time, objectively-measured sleep during titration predicts future adherence [27]. In our clinical experience, it is the interaction of these subjective and objective factors that determines acceptance and adherence to CPAP. As illustration, in the current study baseline insomnia complaints might have negatively impacted objective sleep during titration, which might have colored patient perception and contributed to poorer CPAP adherence. Unfortunately, data were unavailable to test this hypothesis in the current project, but current findings suggest the utility of such investigation. A related inquiry would involve subjective and objective responses to CPAP pressures during titration (eg, stage shifts, REM consolidation,. etc), and their relations to CPAP use and treatment outcome among SDB patients. Among patients experiencing co-morbid insomnia, it is possible that acclimation to CPAP pressures might increase anxiety or somaticized tension in these patients, thereby worsening titration experience and negatively impacting likelihood of successful adaptation of CPAP. The past decade has seen increasing recognition of challenges associated with CPAP adherence as well as interest in improving CPAP use, and promising development of treatments to enhance CPAP adherence [25]. To our knowledge, these are the first results to objectively document that insomnia can be a risk factor for poorer CPAP adherence. Our data provide clear support for future investigation on whether and by what mechanisms (eg, objective sleep and patient subjective experience) improving insomnia symptoms might increase CPAP adherence. Among non-selected patients, a recent double-blind, randomized controlled trial found
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that administration of 3mg eszopiclone during titration was associated with improved sleep (including reduced AHI) during titration and greater CPAP adherence at 6-weeks [28]. However, CMS adherence even in the eszopiclone group showed significant room for improvement (53.1% or 44.1%, depending on analysis), and patient subjective experience was not reported. Similarly, in a study of patients with severe OSA [29], 3mg eszopiclone during the first two weeks of CPAP use was associated with improved adherence relative to placebo, with 48% of treated patients (vs. 25% of controls) meeting CMS criteria for adherence at 6-month follow-up. These authors describe an admirable routine clinical approach to maximizing CPAP adherence at Walter Reed Army Medical Center, including thoroughly educating patients regarding OSA, CPAP, and treatment alternatives, and using nonpharmalogical intervention as first-line approaches. However, patient perceptions were again not reported, further supporting the need for greater understanding regarding the interaction between objective disease and subjective psychological factors in CPAP use. In terms of clinical implications, the current project supports the importance of proactively identifying modifiable, patient-specific factors likely to influence CPAP use, and modifying treatment plans accordingly. For comprehensive sleep medicine programs with behavioral sleep medicine specialists on staff, this process can be greatly aided by evaluating patient-specific psychological factors such as attitudes and beliefs and self-efficacy to use CPAP, along with insomnia complaints, prior to CPAP titration. In addition to thoroughly educating patients regarding OSA, CPAP, and treatment alternatives, providers can then incorporate results of this brief formal assessment into treatment plans and recommend additional intervention as indicated. In our clinical practices, such additional intervention typically involves proactive clinical followup and/or direct referral to specialists in behavioral sleep medicine for cognitive-behavioral therapy for CPAP adherence (eg, [30]) or combined cognitive-behavioral therapy for CPAP and insomnia (eg, [19]). Treating patients experiencing combined insomnia and OSA can be challenging and typically requires significant face to face time with patients. Based on our clinical experience, the practice of comprehensive sleep medicine requires a truly interdisciplinary approach, including sleep medicine and behavioral sleep medicine specialists in routine patient care, under one roof. Although this approach may not yet be feasible in all sleep medicine centers due to the well-documented shortage of trained behavioral sleep medicine specialists [31], it combines current ‘‘gold standard” treatments for CPAP adherence (eg, [32]) and insomnia [33] for patients with this very common clinical presentation. Readers are referred to a recent review for more detailed discussion of these issues [3]. As is the case with any case series study, a number of limitations must be noted. First, although the current data is prospective, study design precludes causal interpretation. Many patient-level factors beyond insomnia might also have influenced CPAP use. At the same time, complaints of sleep maintenance insomnia were unrelated to AHI, and all statistical analyses controlled for age and gender, two well-known insomnia correlates. Second, these results are based on a sample of patients with moderate to severe sleep apnea who reported for clinical follow-up after being prescribed CPAP. The generalizability to other patient populations is unknown. Although our sample size was well powered for statistical analysis [34] and participants were likely representative of similar types of patients seen in sleep medicine centers, larger sample sizes and replication among other types of patients (eg, mild SDB) are required. Third, as indicated above insomnia complaints were assessed via only three individual self-report items. Two insomnia items were highly correlated, which influenced our analytic strategy. Similarly, insomnia complaints were only measured at one point in time. In addition to more comprehensive insomnia
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