Treatment of Obstructive Sleep Apnea with Nasal Continuous Positive Airway Pressure Patient Compliance, Perception of Benefits, and Side Effects1.2
V. HOFFSTEIN, S. VINER, S. MATEIKA, and J. CONWAY
Introduction
Since the original description of continuous positive airway pressure (CPAP) administered via nasal mask (l) for the treatment of obstructive sleep apnea (OSA), this method has become the most widely used nonsurgical alternative for treating this disorder (2, 3). It is highly successful in reducing the number of episodes of airway obstruction during sleep, and it improves or completely resolves clinical symptoms and adverse physiologic consequences of sleep apnea. Since treatment with nasal CPAP is unlike any other conventional medical therapy, a great deal of commitment on the part of the patient is required, and the issue of compliance becomes of crucial importance. Multiple factors influence the acceptance of nasal CPAP by patients. These include mechanical characteristics of the device, such as its weight, dimensions, and portability. Noise level, tolerance by the bed partner, and social embarrassment are also important factors. Side effects related to the mask and air pressure influence the acceptance of this treatment by patients. Finally, another very important factor is the cost of the system (approximately CA $1,300), which may be prohibitively expensive to many patients with sleep apnea. In this respect Ontario is unusual since 750/0 of the cost ofCPAP is paid by the Ministry of Health. Almost all the private insurance carriers provide the remaining 25 % coverage. Consequently, in Ontario financial considerations do not play an important role in a patient's decision regarding nasal CPAP. The major reason for this study was to examine the compliance of patients with sleep apnea started on home CPAP. A unique feature of this study, not present in previous investigations, was detailed attention to patients' perceptions ofthe CPAP system, including their (and
SUMMARY Obstructive sleep apnea is a chronic disease whose treatment may require long-term nightly use of relatively cumbersome and expensive breathing equipment that provides continuous positive airway pressure (CPAP)via nasal mask. Compliance with this treatment may be Influenced not only by the objective Improvement In sleep apnea but also by the patient's subjective perception of the benefit, bed mate or family support, side effects, and cost. The last factor may not be Important In Ontario, where 75% of the cost is paid by the Ministry of Health. The goal of this study was to analyze the factors that may influence patient acceptance of nasal CPAP. This was done by tabulating the responses to a detailed questionnaire mailed to 148patients with obstructive sleep apnea (OSA). There were 96 replies. We were able to contact by telephone an additional 42 patients. The results showed that 105patients continued to use CPAP at a mean follow-up time of 17 ± 11 months, some for as long as 6 yr. The majority of patients (81%) perceived CPAP as an effective treatment of the disorder, 5% were unsure, and 14% believed that CPAP was ineffective, despite the resolution of sleep apnea on polysomnography. Subjective Improvement reported by the patients was also observed by the family members In 83% of the patients. The most common complaint, voiced by 46% of the patients, was nocturnal awakenings. Nasal problems, such as dryness, congestion, and sneezing, were the second most frequent complaint present In 44% of the responders. Of the 96 patients who completed the questionnaire, 17 returned nasal CPAP after an average of 3 ± 4 months of use, resulting In a compliance rate of 82%, similar to previous studies conducted in patient populations without government-sponsored insurance programs. The noncompliant patients did not differ in the severity of apnea or response to treatment from those who kept the equipment, but a significantly greater proportion did not perceive any beneficial effects, their families did not notice any improvement, anclthese patients voiced significantly more adverse comments about the CPAPequipment than those who kept It. We conclude that although many patients report adverse side effects of CPAp,the compliance with this treatment Is relatively high and a large majority of patients (81%) believe that the treatment Is beneficial. We further conclude that essentially cost-free access to home CPAPequipment does not improve the compliance over that previously reported in the literature. AM REV RESPIR DIS 1992; 145:841-845
their families) impression about the beneficial effects of this treatment, complaints about the equipment, side effects, and suggestions for improvement. A secondary goal of this study was to compare the compliance with CPAP in Ontario patients with that reported in other patient populations, in which the accessibility to CPAP may not be as easy as in our province. Methods Patients Wereviewed the files of 148patients with obstructive sleep apnea who were started on nasal CPAP at home between 1987and January 1989.All patients were initially referred to our sleep clinic because of suspicion of sleep apnea, all had nocturnal polysomnography, and
in all the diagnosis of obstructive sleep apnea was established by demonstrating apnea and hypopnea index (AHI) of greater than 10. In addition to the initial diagnostic sleep study, all patients had a follow-up study with CPAP. Once the appropriate CPAP level was established, based on the reduction in AHI to less than 10, each patient was fitted indi-
(Received in original form May 8, 1991 and in revised form July 29, 1991) 1 From the Departments of Medicine and Anesthesia, St. Michael's Hospital, Toronto, Ontario, Canada. 2 Correspondence and requests for reprints should be addressed to Dr. V. Hoffstein, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario, Canada M5B lW8.
841
842
HOFFSTEIN, VINER, MATEIKA, AND CONWAY
TABLE 1
Results
QUESTIONNAIRE FOR EVALUATION OF HOME CPAP
Of the 148 patients to whom the questionnaires were mailed, 96 replied. Of these, 79 patients reported that they continued to use the CPAP system at the time of follow-up (17 ± 11 months), and 17 patients returned the equipment after an average use of 3 ± 4 months. Of the 52 patients who did not reply, we were successful in contacting by telephone or in person 42; 16 patients reported that they no longer used CPAP, and 26 patients continued to use the equipment. The remaining 10 patients could not be contacted despite many different attempts. Counting only the patients who returned the questionnaire, the acceptance rate of CPAP is 79 in 96 (82070). If we count all the patients who continued to use CPAP at the time of follow-up (whether they returned the questionnaire or not), the acceptance rate of CPAP is at best 76070 (105 of 138)and at worst 71 % (105 of 148).
When did you start using CPAP at home? How many nightslweek do you use CPAP? On the average, how many hours/night do you use CPAP? On the average, how many hours/night do you sleep? If you stopped using CPAP, when? Why? 1. 2. 3. 4. 5. 6. 7. 8.
What was your major problem while awake? What was your major problem during sleep? Have you noticed any changes in how you feel since you started CPAP? Have your family or friends noticed any changes in your behavior since you started using CPAP? Has the CPAP been effective in treating your problem? Have you noticed any side effects caused by the nasal CPAP unit? Do you have any complaints or comments about the equipment? Do you have any other comments or suggestions?
vidually with a nasal mask and received the CPAP system at home. Questionnaires (see later) were mailed to all 148 patients. There were 96 replies; of the remaining 52 patients who did not reply, we weresuccessful in contactingbyphone 42. The other 10 patients could not be contacted and wereconsidered lost to follow-up. The set of 96 patients who fullycompletedand returned the questionnaireconstitutesthe study group. All patients wereusingthe Respironics SleepEasy@ SystemII or III (Respironics Inc.,Monroeville, PA). CompliancewithCPAP wasdefined as persistent (although not necessarily daily) use of CPAP at the time of follow-up. Questionnaire In designing the questionnaire (table 1), we tried to avoid an excessively rigid and complexformat. Our goal wasto havea short and easilyunderstood questionnaire to maximize patient participation. Wetried to avoid using analog visual scalesand instead concentrated on the ''yes'' or "no" answersto givenquestions and choices. There were eight simple questions. The respondents were given a
choice of severalanswers to most questions. These possible answers were based on the common complaints and comments voiced by patients on home CPAP during their clinical follow-upvisits. Any number of answers could be selected, and the patients were encouraged to write in their own answers. Statistical Analysis All numeric variables, such as anthropometric and sleep study data, were summarized by reporting means and standard deviations. Paired t tests wereused to compare the apnea and hypopnea indices and lowest nocturnal oxygensaturations beforeand on CPAP.Unpaired t tests wereused to comparethese variablesbetween the patientswho keptthe equipment and those who returned it. All questionnaire responses were tabulated, and the frequency of individual responses wascounted. Chi-square tests of independence wereused to compare the repliesof patients who returned CPAP equipment versus those who kept it. SASsoftware, Version 6.04 (SASInstitute, Cary,NC), wasused for allstatisticalanalysis.
TABLE 2 ANTHROPOMETRIC AND SLEEP APNEA DATA OF PATIENTS ON HOME CPAP Compliant Patients N Age, yr Weight, kg BMI, kglm 2 AHI, no.lh Low O2 sat, Ok Mean O2 sat, % Pressure, cm H2O Use nights/week Use h/night Sleep h/night AHI (CPAP) Low O2 sat (CPAP) Mean O2 sat (CPAP) Months on CPAP
Noncompliant Patients
79 51 102 34 56 68 92 9 6 6 7 9 89 94 17
± ± ± ± ± ± ± ± ± ± ± ± ± ±
p Value
17 11 24 8 32 14 4 3 2 2 1 14 5 2 11
49 91 30 47 72 92 8 5 4 7 12 88 94 3
± ± ± ± ± ± ± ± ± ± ± ± ± ±
12 16 6 36 16 4 3 3 3 2 13 7 2 4
NS NS
< 0.05 NS NS NS NS NS
< 0.01 NS NS NS NS
< 0.001
Definition of abbreviations: AHI = apnealhypopnea index; 8MI = body mass index; low (mean) O2 sat = lowest (mean) nocturnal oxygen saturation; use nights/week = number of nights per week CPAP is used; use h/night = number of hours per night CPAP is used; sleep h/night = number of hours per night spent asleep. Variable names followed by CPAP refer to "while using CPAP."
Objective Effects of CPAP The analysis that follows is limited to 96 patients who replied to the questionnaire. The group consisted of 11 women and 85 men, ranging in age from 28 to 76 yr. They were significantly obese, with a body mass index of 33 ± 8 kg/m" (range 19 to 63). All patients had obstructive sleep apnea with a mean apnea and hypopnea index of 54 ± 31 (range 11 to 153). The lowest nocturnal oxygen saturation was 68 ± 160/0 (range 32 to 91 %), and mean nocturnal oxygen saturation was 91 ± 4070 (range 75 to 97%). Continuous positive airway pressure of 9 ± 3 em H 20 (range 4 to 17.5 em H 20) was effective in abolishing airway obstruction during sleep. The apnea and hypopnea index decreased to 9 ± 13, the lowest nocturnal oxygen saturation improved to 89 ± 50/0, and the mean nocturnal oxygen saturation increased slightly but significantly to 94 ± 2 %. Patients who kept the CPAP system were somewhat more obese than those who returned it and used it more hours during the night (table 2).
Subjective Effects of CPAP: Analysis of Questionnaires Responses to questions listed in table 1 are summarized in figures 1 through 7. . Each patient was allowed to write as many different responses to a given question as desired; in figure captions, we preserved the actual wording of the patients.
843
TREATMENT OF OBSTRUCTIVE SLEEP APNEA WITH NASAL CPAP
INo. of pts)
70
Fig. 1. Responses to question, What was your major problem while awake? SLEEpy, excessive daytime sleepiness, tiredness, and lack of energy; DOZY, dozing off; HDCHS, headaches; MEMRV, bad memory; IRRIT; irritable, anxious; CONC, inability to concentrate; ACHES, leg and body aches; OTHER, loss of oxygen, discomfort, dull eyes.
SLEEPY
DOZY
NONE
HDCHS
MEMRY
IRRIT
CONC
ACHES
OTHER
INo. of pts]
50
Fig. 2. Responses to question, What was your major problem during sleep? SNOR, snoring; FRAGM, interrupted sleep; NTMR, nightmares and dreams; HEAD, headaches; LOO2, low oxygen; MUC, mucus in the throat; SORE, sore throat in the morning; OTHER, forgetfulness, waking up tired, dry nasal passages, reduced sleep, headaches, claustrophobia, legs twitching, uncontrolled body movements, cardiac arrhythmia. SNOR APNEA FRAGM NTMR HEAD NONE
L002
MUC
SORE OTHER
(No. of pts)
70
Fig. 3. Responses to question, Have you noticed any changes in how you feel since you started CPAP? AWKE, awake; SCRE, secure; HDCH, headache; ANXT,anxiety; CNG, congested; IMPR, improvement; IRRIT, irritable.
MORE
MORE
LESS
LESS
LESS
AWKE
SCRE
HDCH
ANXT
CNG
The first two questions deal with the initial problem during wakefulness(Question 1) or during sleep (Question 2), as perceived by the patients, which precipitated their initial visit to the sleep clinic. As may be seen from the answers given in figures 1 and 2, most patients' initial complaint was daytime sleepiness, tiredness, lack of energy, dozing off, and headaches. Their perceivedproblem during sleep was either snoring or apnea, although many complained of fragmented sleep and nightmares. The next series of three questions deals with the benefit of CPAP as perceived by the patients themselves (figure 3) or their families (figure 4). Wenote that after institution of treatment with CPAP, only 14 patients reported no improve-
NO
CHEST
IMPR
PAIN
NAUS
LESS IRRIT
ment. A significant (chi-square = 24, p < 0.0001) proportion (nine patients) returned CPAP, but five continued to keep it. Of the other 72 patients, many reported feeling more awake and secure; some felt lessirritable. A significant number reported fewer headaches, less anxiety' and less nasal congestion. There were three patients who reported chest pains occurring since the institution of CPAP therapy, and one patient reported nausea. Not only patients themselves, but their families, bed mates, and friends noticed improvement. Snoring disappeared in 76 patients, and many others werenoted to look more relaxed, more energetic, and healthier. There were 16 patients whose family and friends did not notice any difference as a result of treatment.
A highly significant (chi-square = 45, p < 0.001) proportion of these (11 patients) themselves perceived no improvement with CPAP, and eight returned it. Overall, 78 patients (81 0/0) believed that CPAP was an effective treatment of the condition, 13patients (140/0) believedthat it was not effective, and fivepatients (50/0) were unsure (figure 5). Responses to question 6 dealing with side effects of CPAP are shown in figure 6. We note that the most common side effect of CPAP, voiced by 44 patients, was waking up during the night. Over 40 patients complained of side effects related to the nose (dryness, soreness, and congestion), throat (dry or in one case dripping), ears (pain), and eyes (pain). Some of these side effects may have been related to slipping of the face mask, reported by 32 patients. Many patients (21) complained of swallowingair, and 10 patients complained of claustrophobia. There were many complaints, comments, and suggestions about the equipment (repliesto Questions 7 and 8). These are tabulated in table 3. Most of the remarks were related to the mask and included tight fit (63complaints) and pain, discomfort, or marks over the face and upper lip (52 complaints). Complaints about the blower were less numerous (65 complaints) and quite uniform: the patients judged the blower either too heavy or too noisy. Other adverse comments were directed to the system in general; many patients complained that the system is too cumbersome, difficult to sleep with, and not portable. Despite all these complaints, there were many positive comments, ranging from increased sex drive to general feeling of well-being. There were 17 patients who returned their equipment after using it for 3 ± 4 months. These patients had similar complaints as the rest of the group. They ranged from claustrophobia, noise, discomfort, to nuisance (figure 7). Chisquare tests showed no significant difference in the incidence and nature of presenting complaints, side effects, or adverse comments about the equipment. However, repliesto Questions 3, 4, 5, and 8 were significantly different in the compliant and noncompliant groups. Within the compliant group, 95% perceived beneficial changes versus 470/0 in the noncompliant group (replies to Question 3; chi-square = 26, p < 0.0001). Perhaps even more important, in 90% of the compliant patients the family also noticed beneficial effects, versus 470/0 of the noncompliant patients (replies to Question 4; chi-square = 17, p < 0.0001). Only
844
HOFFSTEIN, VINER, MATEIKA, AND CONWAY
INo. of pts)
(No. of pts)
50
80
LESS
MORE
SNORING
ENERGY
MORE RELAXED
IMPROVED HEALTH
NO CHANGE
WAKE UP
NOS E PRO B l EMS DRY
CNG
DRP
SNZ
SORE
MASK
AIR
SLIP
SWLW
NONE
Fig, 4. Responses to question, Have your family or friends noticed any changes in your behavior since you started using CPAP?
10070 of compliant patients had any adverse comments about the CPAP equipment versus 59% of the noncompliant patients (repliesto Question 8; chi-square 22, p < 0.0001). Discussion
This study indicates that despite the fact that nasal CPAP is relatively bulky and cumbersome, over 70% of patients with sleep apnea accept it and continue to use it, some for several years. There are relatively few studies (4-12) investigating long-term compliance with nasal CPAP in which the follow-up included enough patients to draw definitive conclusions. One of the first such studies was that of Sanders and colleagues (7) who found 85070 compliance (17 of 20 patients) after a mean followup of 10 months. Issa and coworkers (9) found that 90% of patients started on nasal CPAP remained on it at the time of follow-up, some for up to 3 yr (105 of 117 patients). Nino-Murcia and colleagues (11) found that 65070 of patients, (90 of 139) continued to use CPAP after a mean follow-up of 11.5 months. The most recent study is that of Waldhorn and coworkers, who found 76070 compliance with nasal CPAP (73 of 96 patients) after an average of 14.5months. In terms of the number of patients, mean follow-
(No. of pts)
80
YES
NO
DON'T KNOW
Fig. 5. Responsesto question, Hasthe CPAPbeen effective in treating your problem?
CLSTR
THROAT
EARS
DRY
HURT
MOUTH DRY
MOUTH DRIP
EYES
COUGH
HURT
Fig. 6, Responses to question, Have you noticed any side effects caused by the nasalCPAPunit? CNG, congested; DRp, drippy; SNZ, sneezing; SLIp, slipping; SWLW, swallowing; CLSTR, claustrophobia.
up time, and acceptance rate of CPAP, our study resembles most that of the Waldhorn (12) and Nino-Murcia groups (11). It should be pointed out that all studies that utilize questionnaires returned by patients havean inherent prolem of self-selection; patients who return questionnaires represent a self-selected group who are probably more compliant that those who do not return the questionnaires. In fact, of the 42 patients who
did not return the questionnaire and were contacted by telephone, only 38% were using CPAP compared with 82070 of the patients who returned the questionnaire. It is well accepted that CPAP is an effective treatment of sleep apnea in terms of objective improvement: reduction in the apnea and hypopnea index and improvement in oxygen saturation. Our data show that CPAP is also an effective treatment for a patient's subjective complaints. Both of the most common complaints voiced by our patients, excessive daytime sleepiness and snoring, were to a large extent eliminated by CPAP. In addition, 19 to 30070 of patients reported feeling more secure and less anxious. These beneficial effects of treatment were noted not only by the patients themselves but also by their bed mates, family, and friends. The design of our questionnaire allowed us to analyze the factors that are most troublesome to patients on nasal CPAP. It is clear from patients' responses that as a group nasal problems account for most of the adverse effects of CPAP. Dry, congested, or drippy noses werenoted by 44 of 96 patients. In our experience, patients on nasal CPAP frequently must discontinue the use of this equipment during upper respiratory infection that causes nasal congestion. Some patients are advised to use nasal decongestants to facilitate their tolerance of the CPAP equipment. The frequency of nasal complaints emphasizes the need for detailed attention and full examination of the na-
TABLE 3 PATIENT COMPLAINTS, COMMENTS, AND SUGGESTIONS REGARDING CPAP EQUIPMENT Adverse Complaints Mask Too tight Hurts the ridge of the nose and upper lip Leaves marks on face and hair Too large Leaks Smells Easy to remove while asleep Blower Too noisy Too heavy Other components of CPAP system Straps wear out too fast Hose droops on face General System not portable System too cumbersome and confining Air too dry and too warm System not durable Difficult to sleep with Feel claustrophobic Difficult to travel with
Frequency
Positive Comments
Frequency
63 46 6 6 1 1 1
Equipment is helpful Feel better Was worthwhile getting used to General health improved Blood pressure normalized Sex drive increased
55 47 45 32 1 1
45 20 10 1 11 45 1 1 2 10 17
TREATMENT OF OBSTRUCTIVE SLEEP APNEA WITH NASAL CPAP
INo of pts l
5
CLSTR NOISY
UNHLP UNCMF CUMB
BRTHE SWLW
SLP
OTHER
Fig. 7. Responsesto question,Whydid you stop using CPAP? CLSTR, claustrophobia; UNHLP, did not improve mycondition; UNCMF, uncomfortable; CUMB,too cumbersomeand confining; BRTHE, could not breathewith it; SWLW, swallowing air; SLP, could not sleep with it on; OTHER, mask slipping off, not portable, exhaust blows on bed partner, pain over eyes in the morning, bodypain, lostweight,fatigue, gas,nuisance, facemask leaksor poorlyfitted,toomuchfuss,morningpanic,nausea, chest pain, changing work shift.
sal airway both during the initial assessment and during follow-up. Another frequent side effect of CPAP is sleep fragmentation. Despite this complaint, most patients report better sleep, with resolution of morning tiredness and reduction in daytime sleepiness. Most of the complaints about CPAP are related to the mask. Although the mask is fitted and adjusted by a respiratory technologist, 62 patients (650,70) complained about the poor fit, usually the mask being too tight; in some patients this causes pain, leavesmarks on the face, or irritates the upper lip and the skin along the contact line between the face and the mask. Other than the mask, the most frequent complaint reported by 45 patients was the noise made by the blower. In line with these complaints, most of the suggestions for improvement dealt with the mask and the blower. Not all patients perceive a subjective improvement from nasal CPAP. Approximately 190,70 of patients (18 of 96) reported that CPAP was not effective in treating the problem, and subsequently 11 of these patients returned the equipment. This lack of subjective improvement does not correlate with objective findings; those who discontinued using CPAP still
845
demonstrated a marked reduction in AHI mask. Cost consideration does not apfrom 47 ± 26 to 12 ± 13. We were un- pear to be an important factor in deterable to find a consistent difference in mining patient compliance. the questionnaire responses between the group of 17 patients who returned the References equipment and the 79 patients who con- 1. Sullivan CE, Issa FG, Berthon-Jones M. Revertinued to use it. The presenting com- sal of obstructive sleep apnea by continuous posiplaints, the incidence of side effects, and tive airway pressureapplied through the nares. Lanthe adverse comments about the equip- cet 1981; 1:862-5. Crowe-McCann C, Nino-Murcia G, Guillement were similar between the two 2. minault C. Nasal CPAP: the Stanford experience. groups. It is possible that this lack of sub- In: Guilleminault C, Partinen M, eds. Obstructive jective improvement was secondary to an sleep apnea syndrome: clinical research and treatadditional problem (nocturnal myoclo- ment. New York: Raven Press, 1990; 119-28. nus) that persisted whilethe patients were 3. Sullivan CE, Grunstein RR. Continuous positive airways pressure in sleep-disordered breathing. on CPAP. None of them had evidence In: Krieger MH, Roth T, Dement WC, eds. Princiof myoclonus on the initial sleep study, ples and practice of sleep medicine. Philadelphia: but we did not consistently investigate W. B. Saunders, 1989; 559-70. this possibility in the follow-up study 4. McEvoy RD, Thornton AT. Treatment of obstructive sleep apnea syndrome with nasal continuwith CPAP. We believe that it is the lack ous positive airway pressure. Sleep 1984;7:313-25. of subjective beneficial effects of CPAP 5. Sullivan CE, Issa FG, Berthon-Jones M, as perceived by the patient and his or her McCauley VB, Costas LJV. Home treatment of obfamily, and the absence of family sup- structive sleep apnea with continuous positive airport, that facilitated patients' decisions way pressure applied through a nose-mask. Bull Eur Physiopathol Respir 1984; 20:49-54. to return the equipment. In this respect 6. Issa FG, Costas LJV, Berthon-Jones M, it would be of value to utilize the present McCauley VB, Bruderer J, Sullivan CEo Nasal results in setting up a counseling program CPAP treatment for obstructive sleep apnea (OSA): designed to reinforce patients' compli- long-term experience with 117 patients. Am Rev Respir Dis 1985; 131:AI03. ance with CPAP. 7. Sanders MH, Gruendl CA, Rogers RM. Patient Weweresurprised that despite easy ac- compliance with nasal CPAP therapy for sleep apcessibility to CPAP in Ontario, our pa- nea. Chest 1986; 90:330-3. tients did not exhibit better compliance 8. Baker JP, Rose V, Ware C. Obstructive sleep than in similar studies from the United apnea: therapeutic compliance. Trans Am Clin Climatol Assoc 1987; 99:224-30. States, where there is no universal, gov- 9. Issa FG, Grunstein R, Bruderer J, et 01. Five ernment-sponsored insurance to cover years' experience with home nasal continuous posithe cost of CPAP equipment. It is possi- tive airway pressuretherapy for the obstructive sleep ble that cost considerations were not a apnea syndrome. In: Peter JH, Podszus T, von eds. Sleep-related disorders and internal factor in the previous studies as a result Wichert, disease. Berlin: Springer-Verlag, 1987; 360-5. of third-party reimbursement schemes. 10. Krieger J, Kurtz D. Objective measurement Another explanation is that compliance of compliance with nasal CPAP treatment for obis not related to cost but to the severity structive sleep apnea syndrome. Eur Respir J 1988; of the disease, so that patients with simi- 1:436-8. 11. Nino-Murcia G, Crowe-McCann C, Bliwise 1ardegrees of sleep apnea may be expect- DL, Guilleminault C, Dement WC. Compliance ed to exhibit similar compliance with and side effects in sleep apnea patients treated with nasal continuous positive airway pressure. West J treatment. Weconclude that CPAP remains a very Med 1989; 150:165-9. 12. Waldhorn RE, Herrick TW, Nguyen MC, effective treatment alternative for pa- O'Donnell AE, Sodero J, Potolicchio SJ. Long-term tients with sleep apnea. It is accepted by compliance with nasal continuous positive airway the majority of patients. The most im- pressure therapy of obstructive sleep apnea. Chest portant side effects are nasal problems, 1990; 97:33-8. and the most frequent complaints about the equipment are related to the nasal
V. HOFFSTEIN, S. VINER, S. MATEIKA, and J. CONWAY
Introduction
Since the original description of continuous positive airway pressure (CPAP) administered via nasal mask (l) for the treatment of obstructive sleep apnea (OSA), this method has become the most widely used nonsurgical alternative for treating this disorder (2, 3). It is highly successful in reducing the number of episodes of airway obstruction during sleep, and it improves or completely resolves clinical symptoms and adverse physiologic consequences of sleep apnea. Since treatment with nasal CPAP is unlike any other conventional medical therapy, a great deal of commitment on the part of the patient is required, and the issue of compliance becomes of crucial importance. Multiple factors influence the acceptance of nasal CPAP by patients. These include mechanical characteristics of the device, such as its weight, dimensions, and portability. Noise level, tolerance by the bed partner, and social embarrassment are also important factors. Side effects related to the mask and air pressure influence the acceptance of this treatment by patients. Finally, another very important factor is the cost of the system (approximately CA $1,300), which may be prohibitively expensive to many patients with sleep apnea. In this respect Ontario is unusual since 750/0 of the cost ofCPAP is paid by the Ministry of Health. Almost all the private insurance carriers provide the remaining 25 % coverage. Consequently, in Ontario financial considerations do not play an important role in a patient's decision regarding nasal CPAP. The major reason for this study was to examine the compliance of patients with sleep apnea started on home CPAP. A unique feature of this study, not present in previous investigations, was detailed attention to patients' perceptions ofthe CPAP system, including their (and
SUMMARY Obstructive sleep apnea is a chronic disease whose treatment may require long-term nightly use of relatively cumbersome and expensive breathing equipment that provides continuous positive airway pressure (CPAP)via nasal mask. Compliance with this treatment may be Influenced not only by the objective Improvement In sleep apnea but also by the patient's subjective perception of the benefit, bed mate or family support, side effects, and cost. The last factor may not be Important In Ontario, where 75% of the cost is paid by the Ministry of Health. The goal of this study was to analyze the factors that may influence patient acceptance of nasal CPAP. This was done by tabulating the responses to a detailed questionnaire mailed to 148patients with obstructive sleep apnea (OSA). There were 96 replies. We were able to contact by telephone an additional 42 patients. The results showed that 105patients continued to use CPAP at a mean follow-up time of 17 ± 11 months, some for as long as 6 yr. The majority of patients (81%) perceived CPAP as an effective treatment of the disorder, 5% were unsure, and 14% believed that CPAP was ineffective, despite the resolution of sleep apnea on polysomnography. Subjective Improvement reported by the patients was also observed by the family members In 83% of the patients. The most common complaint, voiced by 46% of the patients, was nocturnal awakenings. Nasal problems, such as dryness, congestion, and sneezing, were the second most frequent complaint present In 44% of the responders. Of the 96 patients who completed the questionnaire, 17 returned nasal CPAP after an average of 3 ± 4 months of use, resulting In a compliance rate of 82%, similar to previous studies conducted in patient populations without government-sponsored insurance programs. The noncompliant patients did not differ in the severity of apnea or response to treatment from those who kept the equipment, but a significantly greater proportion did not perceive any beneficial effects, their families did not notice any improvement, anclthese patients voiced significantly more adverse comments about the CPAPequipment than those who kept It. We conclude that although many patients report adverse side effects of CPAp,the compliance with this treatment Is relatively high and a large majority of patients (81%) believe that the treatment Is beneficial. We further conclude that essentially cost-free access to home CPAPequipment does not improve the compliance over that previously reported in the literature. AM REV RESPIR DIS 1992; 145:841-845
their families) impression about the beneficial effects of this treatment, complaints about the equipment, side effects, and suggestions for improvement. A secondary goal of this study was to compare the compliance with CPAP in Ontario patients with that reported in other patient populations, in which the accessibility to CPAP may not be as easy as in our province. Methods Patients Wereviewed the files of 148patients with obstructive sleep apnea who were started on nasal CPAP at home between 1987and January 1989.All patients were initially referred to our sleep clinic because of suspicion of sleep apnea, all had nocturnal polysomnography, and
in all the diagnosis of obstructive sleep apnea was established by demonstrating apnea and hypopnea index (AHI) of greater than 10. In addition to the initial diagnostic sleep study, all patients had a follow-up study with CPAP. Once the appropriate CPAP level was established, based on the reduction in AHI to less than 10, each patient was fitted indi-
(Received in original form May 8, 1991 and in revised form July 29, 1991) 1 From the Departments of Medicine and Anesthesia, St. Michael's Hospital, Toronto, Ontario, Canada. 2 Correspondence and requests for reprints should be addressed to Dr. V. Hoffstein, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario, Canada M5B lW8.
841
842
HOFFSTEIN, VINER, MATEIKA, AND CONWAY
TABLE 1
Results
QUESTIONNAIRE FOR EVALUATION OF HOME CPAP
Of the 148 patients to whom the questionnaires were mailed, 96 replied. Of these, 79 patients reported that they continued to use the CPAP system at the time of follow-up (17 ± 11 months), and 17 patients returned the equipment after an average use of 3 ± 4 months. Of the 52 patients who did not reply, we were successful in contacting by telephone or in person 42; 16 patients reported that they no longer used CPAP, and 26 patients continued to use the equipment. The remaining 10 patients could not be contacted despite many different attempts. Counting only the patients who returned the questionnaire, the acceptance rate of CPAP is 79 in 96 (82070). If we count all the patients who continued to use CPAP at the time of follow-up (whether they returned the questionnaire or not), the acceptance rate of CPAP is at best 76070 (105 of 138)and at worst 71 % (105 of 148).
When did you start using CPAP at home? How many nightslweek do you use CPAP? On the average, how many hours/night do you use CPAP? On the average, how many hours/night do you sleep? If you stopped using CPAP, when? Why? 1. 2. 3. 4. 5. 6. 7. 8.
What was your major problem while awake? What was your major problem during sleep? Have you noticed any changes in how you feel since you started CPAP? Have your family or friends noticed any changes in your behavior since you started using CPAP? Has the CPAP been effective in treating your problem? Have you noticed any side effects caused by the nasal CPAP unit? Do you have any complaints or comments about the equipment? Do you have any other comments or suggestions?
vidually with a nasal mask and received the CPAP system at home. Questionnaires (see later) were mailed to all 148 patients. There were 96 replies; of the remaining 52 patients who did not reply, we weresuccessful in contactingbyphone 42. The other 10 patients could not be contacted and wereconsidered lost to follow-up. The set of 96 patients who fullycompletedand returned the questionnaireconstitutesthe study group. All patients wereusingthe Respironics SleepEasy@ SystemII or III (Respironics Inc.,Monroeville, PA). CompliancewithCPAP wasdefined as persistent (although not necessarily daily) use of CPAP at the time of follow-up. Questionnaire In designing the questionnaire (table 1), we tried to avoid an excessively rigid and complexformat. Our goal wasto havea short and easilyunderstood questionnaire to maximize patient participation. Wetried to avoid using analog visual scalesand instead concentrated on the ''yes'' or "no" answersto givenquestions and choices. There were eight simple questions. The respondents were given a
choice of severalanswers to most questions. These possible answers were based on the common complaints and comments voiced by patients on home CPAP during their clinical follow-upvisits. Any number of answers could be selected, and the patients were encouraged to write in their own answers. Statistical Analysis All numeric variables, such as anthropometric and sleep study data, were summarized by reporting means and standard deviations. Paired t tests wereused to compare the apnea and hypopnea indices and lowest nocturnal oxygensaturations beforeand on CPAP.Unpaired t tests wereused to comparethese variablesbetween the patientswho keptthe equipment and those who returned it. All questionnaire responses were tabulated, and the frequency of individual responses wascounted. Chi-square tests of independence wereused to compare the repliesof patients who returned CPAP equipment versus those who kept it. SASsoftware, Version 6.04 (SASInstitute, Cary,NC), wasused for allstatisticalanalysis.
TABLE 2 ANTHROPOMETRIC AND SLEEP APNEA DATA OF PATIENTS ON HOME CPAP Compliant Patients N Age, yr Weight, kg BMI, kglm 2 AHI, no.lh Low O2 sat, Ok Mean O2 sat, % Pressure, cm H2O Use nights/week Use h/night Sleep h/night AHI (CPAP) Low O2 sat (CPAP) Mean O2 sat (CPAP) Months on CPAP
Noncompliant Patients
79 51 102 34 56 68 92 9 6 6 7 9 89 94 17
± ± ± ± ± ± ± ± ± ± ± ± ± ±
p Value
17 11 24 8 32 14 4 3 2 2 1 14 5 2 11
49 91 30 47 72 92 8 5 4 7 12 88 94 3
± ± ± ± ± ± ± ± ± ± ± ± ± ±
12 16 6 36 16 4 3 3 3 2 13 7 2 4
NS NS
< 0.05 NS NS NS NS NS
< 0.01 NS NS NS NS
< 0.001
Definition of abbreviations: AHI = apnealhypopnea index; 8MI = body mass index; low (mean) O2 sat = lowest (mean) nocturnal oxygen saturation; use nights/week = number of nights per week CPAP is used; use h/night = number of hours per night CPAP is used; sleep h/night = number of hours per night spent asleep. Variable names followed by CPAP refer to "while using CPAP."
Objective Effects of CPAP The analysis that follows is limited to 96 patients who replied to the questionnaire. The group consisted of 11 women and 85 men, ranging in age from 28 to 76 yr. They were significantly obese, with a body mass index of 33 ± 8 kg/m" (range 19 to 63). All patients had obstructive sleep apnea with a mean apnea and hypopnea index of 54 ± 31 (range 11 to 153). The lowest nocturnal oxygen saturation was 68 ± 160/0 (range 32 to 91 %), and mean nocturnal oxygen saturation was 91 ± 4070 (range 75 to 97%). Continuous positive airway pressure of 9 ± 3 em H 20 (range 4 to 17.5 em H 20) was effective in abolishing airway obstruction during sleep. The apnea and hypopnea index decreased to 9 ± 13, the lowest nocturnal oxygen saturation improved to 89 ± 50/0, and the mean nocturnal oxygen saturation increased slightly but significantly to 94 ± 2 %. Patients who kept the CPAP system were somewhat more obese than those who returned it and used it more hours during the night (table 2).
Subjective Effects of CPAP: Analysis of Questionnaires Responses to questions listed in table 1 are summarized in figures 1 through 7. . Each patient was allowed to write as many different responses to a given question as desired; in figure captions, we preserved the actual wording of the patients.
843
TREATMENT OF OBSTRUCTIVE SLEEP APNEA WITH NASAL CPAP
INo. of pts)
70
Fig. 1. Responses to question, What was your major problem while awake? SLEEpy, excessive daytime sleepiness, tiredness, and lack of energy; DOZY, dozing off; HDCHS, headaches; MEMRV, bad memory; IRRIT; irritable, anxious; CONC, inability to concentrate; ACHES, leg and body aches; OTHER, loss of oxygen, discomfort, dull eyes.
SLEEPY
DOZY
NONE
HDCHS
MEMRY
IRRIT
CONC
ACHES
OTHER
INo. of pts]
50
Fig. 2. Responses to question, What was your major problem during sleep? SNOR, snoring; FRAGM, interrupted sleep; NTMR, nightmares and dreams; HEAD, headaches; LOO2, low oxygen; MUC, mucus in the throat; SORE, sore throat in the morning; OTHER, forgetfulness, waking up tired, dry nasal passages, reduced sleep, headaches, claustrophobia, legs twitching, uncontrolled body movements, cardiac arrhythmia. SNOR APNEA FRAGM NTMR HEAD NONE
L002
MUC
SORE OTHER
(No. of pts)
70
Fig. 3. Responses to question, Have you noticed any changes in how you feel since you started CPAP? AWKE, awake; SCRE, secure; HDCH, headache; ANXT,anxiety; CNG, congested; IMPR, improvement; IRRIT, irritable.
MORE
MORE
LESS
LESS
LESS
AWKE
SCRE
HDCH
ANXT
CNG
The first two questions deal with the initial problem during wakefulness(Question 1) or during sleep (Question 2), as perceived by the patients, which precipitated their initial visit to the sleep clinic. As may be seen from the answers given in figures 1 and 2, most patients' initial complaint was daytime sleepiness, tiredness, lack of energy, dozing off, and headaches. Their perceivedproblem during sleep was either snoring or apnea, although many complained of fragmented sleep and nightmares. The next series of three questions deals with the benefit of CPAP as perceived by the patients themselves (figure 3) or their families (figure 4). Wenote that after institution of treatment with CPAP, only 14 patients reported no improve-
NO
CHEST
IMPR
PAIN
NAUS
LESS IRRIT
ment. A significant (chi-square = 24, p < 0.0001) proportion (nine patients) returned CPAP, but five continued to keep it. Of the other 72 patients, many reported feeling more awake and secure; some felt lessirritable. A significant number reported fewer headaches, less anxiety' and less nasal congestion. There were three patients who reported chest pains occurring since the institution of CPAP therapy, and one patient reported nausea. Not only patients themselves, but their families, bed mates, and friends noticed improvement. Snoring disappeared in 76 patients, and many others werenoted to look more relaxed, more energetic, and healthier. There were 16 patients whose family and friends did not notice any difference as a result of treatment.
A highly significant (chi-square = 45, p < 0.001) proportion of these (11 patients) themselves perceived no improvement with CPAP, and eight returned it. Overall, 78 patients (81 0/0) believed that CPAP was an effective treatment of the condition, 13patients (140/0) believedthat it was not effective, and fivepatients (50/0) were unsure (figure 5). Responses to question 6 dealing with side effects of CPAP are shown in figure 6. We note that the most common side effect of CPAP, voiced by 44 patients, was waking up during the night. Over 40 patients complained of side effects related to the nose (dryness, soreness, and congestion), throat (dry or in one case dripping), ears (pain), and eyes (pain). Some of these side effects may have been related to slipping of the face mask, reported by 32 patients. Many patients (21) complained of swallowingair, and 10 patients complained of claustrophobia. There were many complaints, comments, and suggestions about the equipment (repliesto Questions 7 and 8). These are tabulated in table 3. Most of the remarks were related to the mask and included tight fit (63complaints) and pain, discomfort, or marks over the face and upper lip (52 complaints). Complaints about the blower were less numerous (65 complaints) and quite uniform: the patients judged the blower either too heavy or too noisy. Other adverse comments were directed to the system in general; many patients complained that the system is too cumbersome, difficult to sleep with, and not portable. Despite all these complaints, there were many positive comments, ranging from increased sex drive to general feeling of well-being. There were 17 patients who returned their equipment after using it for 3 ± 4 months. These patients had similar complaints as the rest of the group. They ranged from claustrophobia, noise, discomfort, to nuisance (figure 7). Chisquare tests showed no significant difference in the incidence and nature of presenting complaints, side effects, or adverse comments about the equipment. However, repliesto Questions 3, 4, 5, and 8 were significantly different in the compliant and noncompliant groups. Within the compliant group, 95% perceived beneficial changes versus 470/0 in the noncompliant group (replies to Question 3; chi-square = 26, p < 0.0001). Perhaps even more important, in 90% of the compliant patients the family also noticed beneficial effects, versus 470/0 of the noncompliant patients (replies to Question 4; chi-square = 17, p < 0.0001). Only
844
HOFFSTEIN, VINER, MATEIKA, AND CONWAY
INo. of pts)
(No. of pts)
50
80
LESS
MORE
SNORING
ENERGY
MORE RELAXED
IMPROVED HEALTH
NO CHANGE
WAKE UP
NOS E PRO B l EMS DRY
CNG
DRP
SNZ
SORE
MASK
AIR
SLIP
SWLW
NONE
Fig, 4. Responses to question, Have your family or friends noticed any changes in your behavior since you started using CPAP?
10070 of compliant patients had any adverse comments about the CPAP equipment versus 59% of the noncompliant patients (repliesto Question 8; chi-square 22, p < 0.0001). Discussion
This study indicates that despite the fact that nasal CPAP is relatively bulky and cumbersome, over 70% of patients with sleep apnea accept it and continue to use it, some for several years. There are relatively few studies (4-12) investigating long-term compliance with nasal CPAP in which the follow-up included enough patients to draw definitive conclusions. One of the first such studies was that of Sanders and colleagues (7) who found 85070 compliance (17 of 20 patients) after a mean followup of 10 months. Issa and coworkers (9) found that 90% of patients started on nasal CPAP remained on it at the time of follow-up, some for up to 3 yr (105 of 117 patients). Nino-Murcia and colleagues (11) found that 65070 of patients, (90 of 139) continued to use CPAP after a mean follow-up of 11.5 months. The most recent study is that of Waldhorn and coworkers, who found 76070 compliance with nasal CPAP (73 of 96 patients) after an average of 14.5months. In terms of the number of patients, mean follow-
(No. of pts)
80
YES
NO
DON'T KNOW
Fig. 5. Responsesto question, Hasthe CPAPbeen effective in treating your problem?
CLSTR
THROAT
EARS
DRY
HURT
MOUTH DRY
MOUTH DRIP
EYES
COUGH
HURT
Fig. 6, Responses to question, Have you noticed any side effects caused by the nasalCPAPunit? CNG, congested; DRp, drippy; SNZ, sneezing; SLIp, slipping; SWLW, swallowing; CLSTR, claustrophobia.
up time, and acceptance rate of CPAP, our study resembles most that of the Waldhorn (12) and Nino-Murcia groups (11). It should be pointed out that all studies that utilize questionnaires returned by patients havean inherent prolem of self-selection; patients who return questionnaires represent a self-selected group who are probably more compliant that those who do not return the questionnaires. In fact, of the 42 patients who
did not return the questionnaire and were contacted by telephone, only 38% were using CPAP compared with 82070 of the patients who returned the questionnaire. It is well accepted that CPAP is an effective treatment of sleep apnea in terms of objective improvement: reduction in the apnea and hypopnea index and improvement in oxygen saturation. Our data show that CPAP is also an effective treatment for a patient's subjective complaints. Both of the most common complaints voiced by our patients, excessive daytime sleepiness and snoring, were to a large extent eliminated by CPAP. In addition, 19 to 30070 of patients reported feeling more secure and less anxious. These beneficial effects of treatment were noted not only by the patients themselves but also by their bed mates, family, and friends. The design of our questionnaire allowed us to analyze the factors that are most troublesome to patients on nasal CPAP. It is clear from patients' responses that as a group nasal problems account for most of the adverse effects of CPAP. Dry, congested, or drippy noses werenoted by 44 of 96 patients. In our experience, patients on nasal CPAP frequently must discontinue the use of this equipment during upper respiratory infection that causes nasal congestion. Some patients are advised to use nasal decongestants to facilitate their tolerance of the CPAP equipment. The frequency of nasal complaints emphasizes the need for detailed attention and full examination of the na-
TABLE 3 PATIENT COMPLAINTS, COMMENTS, AND SUGGESTIONS REGARDING CPAP EQUIPMENT Adverse Complaints Mask Too tight Hurts the ridge of the nose and upper lip Leaves marks on face and hair Too large Leaks Smells Easy to remove while asleep Blower Too noisy Too heavy Other components of CPAP system Straps wear out too fast Hose droops on face General System not portable System too cumbersome and confining Air too dry and too warm System not durable Difficult to sleep with Feel claustrophobic Difficult to travel with
Frequency
Positive Comments
Frequency
63 46 6 6 1 1 1
Equipment is helpful Feel better Was worthwhile getting used to General health improved Blood pressure normalized Sex drive increased
55 47 45 32 1 1
45 20 10 1 11 45 1 1 2 10 17
TREATMENT OF OBSTRUCTIVE SLEEP APNEA WITH NASAL CPAP
INo of pts l
5
CLSTR NOISY
UNHLP UNCMF CUMB
BRTHE SWLW
SLP
OTHER
Fig. 7. Responsesto question,Whydid you stop using CPAP? CLSTR, claustrophobia; UNHLP, did not improve mycondition; UNCMF, uncomfortable; CUMB,too cumbersomeand confining; BRTHE, could not breathewith it; SWLW, swallowing air; SLP, could not sleep with it on; OTHER, mask slipping off, not portable, exhaust blows on bed partner, pain over eyes in the morning, bodypain, lostweight,fatigue, gas,nuisance, facemask leaksor poorlyfitted,toomuchfuss,morningpanic,nausea, chest pain, changing work shift.
sal airway both during the initial assessment and during follow-up. Another frequent side effect of CPAP is sleep fragmentation. Despite this complaint, most patients report better sleep, with resolution of morning tiredness and reduction in daytime sleepiness. Most of the complaints about CPAP are related to the mask. Although the mask is fitted and adjusted by a respiratory technologist, 62 patients (650,70) complained about the poor fit, usually the mask being too tight; in some patients this causes pain, leavesmarks on the face, or irritates the upper lip and the skin along the contact line between the face and the mask. Other than the mask, the most frequent complaint reported by 45 patients was the noise made by the blower. In line with these complaints, most of the suggestions for improvement dealt with the mask and the blower. Not all patients perceive a subjective improvement from nasal CPAP. Approximately 190,70 of patients (18 of 96) reported that CPAP was not effective in treating the problem, and subsequently 11 of these patients returned the equipment. This lack of subjective improvement does not correlate with objective findings; those who discontinued using CPAP still
845
demonstrated a marked reduction in AHI mask. Cost consideration does not apfrom 47 ± 26 to 12 ± 13. We were un- pear to be an important factor in deterable to find a consistent difference in mining patient compliance. the questionnaire responses between the group of 17 patients who returned the References equipment and the 79 patients who con- 1. Sullivan CE, Issa FG, Berthon-Jones M. Revertinued to use it. The presenting com- sal of obstructive sleep apnea by continuous posiplaints, the incidence of side effects, and tive airway pressureapplied through the nares. Lanthe adverse comments about the equip- cet 1981; 1:862-5. Crowe-McCann C, Nino-Murcia G, Guillement were similar between the two 2. minault C. Nasal CPAP: the Stanford experience. groups. It is possible that this lack of sub- In: Guilleminault C, Partinen M, eds. Obstructive jective improvement was secondary to an sleep apnea syndrome: clinical research and treatadditional problem (nocturnal myoclo- ment. New York: Raven Press, 1990; 119-28. nus) that persisted whilethe patients were 3. Sullivan CE, Grunstein RR. Continuous positive airways pressure in sleep-disordered breathing. on CPAP. None of them had evidence In: Krieger MH, Roth T, Dement WC, eds. Princiof myoclonus on the initial sleep study, ples and practice of sleep medicine. Philadelphia: but we did not consistently investigate W. B. Saunders, 1989; 559-70. this possibility in the follow-up study 4. McEvoy RD, Thornton AT. Treatment of obstructive sleep apnea syndrome with nasal continuwith CPAP. We believe that it is the lack ous positive airway pressure. Sleep 1984;7:313-25. of subjective beneficial effects of CPAP 5. Sullivan CE, Issa FG, Berthon-Jones M, as perceived by the patient and his or her McCauley VB, Costas LJV. Home treatment of obfamily, and the absence of family sup- structive sleep apnea with continuous positive airport, that facilitated patients' decisions way pressure applied through a nose-mask. Bull Eur Physiopathol Respir 1984; 20:49-54. to return the equipment. In this respect 6. Issa FG, Costas LJV, Berthon-Jones M, it would be of value to utilize the present McCauley VB, Bruderer J, Sullivan CEo Nasal results in setting up a counseling program CPAP treatment for obstructive sleep apnea (OSA): designed to reinforce patients' compli- long-term experience with 117 patients. Am Rev Respir Dis 1985; 131:AI03. ance with CPAP. 7. Sanders MH, Gruendl CA, Rogers RM. Patient Weweresurprised that despite easy ac- compliance with nasal CPAP therapy for sleep apcessibility to CPAP in Ontario, our pa- nea. Chest 1986; 90:330-3. tients did not exhibit better compliance 8. Baker JP, Rose V, Ware C. Obstructive sleep than in similar studies from the United apnea: therapeutic compliance. Trans Am Clin Climatol Assoc 1987; 99:224-30. States, where there is no universal, gov- 9. Issa FG, Grunstein R, Bruderer J, et 01. Five ernment-sponsored insurance to cover years' experience with home nasal continuous posithe cost of CPAP equipment. It is possi- tive airway pressuretherapy for the obstructive sleep ble that cost considerations were not a apnea syndrome. In: Peter JH, Podszus T, von eds. Sleep-related disorders and internal factor in the previous studies as a result Wichert, disease. Berlin: Springer-Verlag, 1987; 360-5. of third-party reimbursement schemes. 10. Krieger J, Kurtz D. Objective measurement Another explanation is that compliance of compliance with nasal CPAP treatment for obis not related to cost but to the severity structive sleep apnea syndrome. Eur Respir J 1988; of the disease, so that patients with simi- 1:436-8. 11. Nino-Murcia G, Crowe-McCann C, Bliwise 1ardegrees of sleep apnea may be expect- DL, Guilleminault C, Dement WC. Compliance ed to exhibit similar compliance with and side effects in sleep apnea patients treated with nasal continuous positive airway pressure. West J treatment. Weconclude that CPAP remains a very Med 1989; 150:165-9. 12. Waldhorn RE, Herrick TW, Nguyen MC, effective treatment alternative for pa- O'Donnell AE, Sodero J, Potolicchio SJ. Long-term tients with sleep apnea. It is accepted by compliance with nasal continuous positive airway the majority of patients. The most im- pressure therapy of obstructive sleep apnea. Chest portant side effects are nasal problems, 1990; 97:33-8. and the most frequent complaints about the equipment are related to the nasal
