Sleep and Breathing

, Volume 12, Issue 4, pp 365–367

CPAP compliance in patients with obstructive sleep apnea syndrome

Authors

    • Department of Pulmonary Medicine, Faculty of MedicineInonu University
  • Erdogan Kunter
    • Department of Pulmonary MedicineMalatya Military Hospital
  • Hakan Gunen
    • Department of Pulmonary Medicine, Faculty of MedicineInonu University
Original Article

DOI: 10.1007/s11325-008-0188-4

Cite this article as:
Yetkin, O., Kunter, E. & Gunen, H. Sleep Breath (2008) 12: 365. doi:10.1007/s11325-008-0188-4

Abstract

Obstructive sleep apnea syndrome (OSAS) is characterized by repeated cessations of breathing during sleep. Major symptoms of this disease are excessive daytime sleepiness, snoring, and witnessed apnea. Most of the patients are treated with CPAP. In this study, we aimed to evaluate the factors affecting adherence to the CPAP treatment. Seventy-one patients were enrolled to this study. Patients were divided into three groups according to CPAP usage. Group I consisted of patients who had never used CPAP, group II consisted of patients who had used CPAP occasionally, and group-III patients had used CPAP treatment regularly. Group-III patients had higher apnea–hypopnea index (AHI) than groups I and II (respectively, 56.6 ± 27.7, 26.3 ± 7.5, and 32.3 ± 7.06; p < 0.000 for both). Oxygen desaturation index was significantly higher in group-III patients comparing to groups I and II (44.6 ± 22.3, 15.9 ± 8.3, and 25.6 ± 9.5; p < 0.000 for all). Our findings have shown that only very severe patients use the CPAP device regularly (mean AHI 56.6 ± 27.7). Compliance to CPAP treatment seemed to be poor in patients with moderate to severe, AHI about 30, OSAS. Considering the well-established benefits of CPAP treatment in patients with true indications, patients should be encouraged to use CPAP regularly, and complications of OSAS should be keynoted.

Keywords

Sleep apneaCPAP treatmentCPAP compliance

Introduction

Obstructive sleep apnea syndrome (OSAS) is a disorder characterized by repeated cessations of breathing during sleep. Consequences of OSAS include excessive daytime sleepiness, divided sleep architecture, impaired neurocognitive performance, and significant psychosocial disruption [1, 2]. Patients with OSAS have increased morbidity from cardiovascular events and work accidents [1, 3]. The treatment modalities for OSAS are nasal continuous positive airway pressure (CPAP) and surgery for some certain conditions. CPAP has been shown to reduce daytime sleepiness, oxyhemoglobin desaturations, heart rate, and pulmonary pressure, improve cognitive performance, and increase quality of life [1, 4].

CPAP treatment is the first choice for most patients with OSAS. In spite of the improvements in CPAP technology, most patients still experience difficulties in tolerating the machine and/or mask, and adherence to the treatment is a clinically significant problem. Level of compliance seems to be related to the severity of the disease as well as to the initial inpatient management session. With respect to the compliance, the first few weeks are critical, as well [5].

In this study, we aimed to evaluate, prospectively, the factors affecting adherence to the CPAP treatment and the correlations of apnea–hypopnea index (AHI), Epworth Sleepiness Scale (ESS), oxygen desaturation index (OD), arousal index (RI), the lowest oxygen saturation (LO), and the body mass index (BMI) with each other, in patients with OSAS.

Methods

Patients

Seventy-one consecutive patients who applied to Sleep Disorders Center of Inonu University Hospital and met the inclusion criteria were enrolled to this study. All patients had nocturnal snoring, excessive daytime sleepiness, and witnessed apnea. ESS [6] was applied to all patients, and cases with high scores (ESS > 10) were accepted into the full-night sleep study. After full-night polysomnography, CPAP device was prescribed to patients with moderate-to-severe OSAS (AHI > 15) and/or excessive daytime sleepiness (ESS > 10). These indications for CPAP treatment were also inclusion criteria. After 3 months, the patients were asked about how good they had adhered to the CPAP treatment. Then, the patients were divided into three groups according to CPAP usage ratio. Group I consisted of patients who had never used CPAP (n = 23), group II consisted of patients who had used CPAP occasionally (n = 24), and group-III patients had used CPAP treatment regularly (n = 24). By definition, patients who did not use CPAP each and everyday of the 3 months period without a valid or acceptable reason (overnight travel, CPAP device dysfunction, etc.) were classified into the group II.

Polysomnography

Full-night polysomnography was performed using conventional instrumentation and analysis according to the recommendations on syndrome definition and measurement techniques published by the American Academy of Sleep Medicine [7]. Sleep stages were detailed by standard electroencephalographic, electro-oculographic, and electromyographic (EMG) criteria. Apneas and hypopneas were recorded by oronasal flow cannulae attached to a pneumotachograph. Arterial oxygen saturation was measured by pulse oximetry using a finger probe. Thoracic and abdominal movements were recorded by using inductive plethysmography to document respiratory effort. Periodical limb movements were recorded from surface EMG electrode on tibialis anterior muscle of the lower extremity. Obstructive apneas were defined as absence of airflow for longer than 10 s; obstructive hypopneas as a 50% decrease in airflow or a clear but lesser decrease in airflow if coupled with either a desaturation of >3% or an arousal in the context of ongoing respiratory effort. All records were scored manually for sleep stage, arousals, apneas, and hypopneas.

Statistical analysis

One-way analysis of variance was applied to compare among the groups. Post-hoc tests were also applied to identify the significant differences between the groups. Spearman correlation test was used to evaluate the correlation between AHI, OD, ESS, LO, and CPAP usage. A p value of <0.05 was considered statistically significant.

Results

Mean age of patients (M/F = 40/31) was 51.5 ± 11.4 (range 30–75; Table 1). AHI, OD, RI, ESS, LO, and BMI were compared between groups. There was no significant difference between groups I and II (p > 0.05) in terms of ESS. ESS of group III was significantly higher than groups I and II (p = 0.007 and p = 0.002, respectively). Group-I patients had lower AHI than group-II patients (p = 0.049). Group-III patients had significantly higher AHI than groups I and II (p < 0.000 for both). Statistically, RI, LO, and BMI were not different in groups. Group III had significantly higher OD than groups I and II patients (p < 0.000 and p = 0.005, respectively; Table 2). Compliance to CPAP treatment was positively correlated with AHI, OD, ESS, RI (r = 0.532, p < 0.000; r = 0.460, p < 0.001; r = 0.348, p = 0.011; r = 0.277, p = 0.04, respectively) and negatively correlated with LO (r = −0.360, p = 0.01). Significant correlation was not detected between compliance to CPAP and BMI (r = 0,134, p = 0,334).
Table 1

Baseline characteristics of patients with obstructive sleep apnea syndrome

 

Mean

Range

Male/female

41/30

 

Mean age

51.5 ± 11.4

30–78

AHI

43.5 ± 24.3

17–144

ESS

11.6 ± 1.4

10–15

BMI

30.2 ± 5.9

22–60

Table 2

Comparison of parameters in patient groups

 

Group I

Group II

Group III

Mean

Range

Mean

Range

Mean

Range

Age

50.3 ± 14

30–71

53.3 ± 9.3

41–63

49.3 ± 10.1

40–78

ESS

11.3 ± 1.2

10–13

11.7 ± 1.8

10–14

12.3 ± 1.7*

11–15

AHI

26.3 ± 7.5***

17–41

32.3 ± 7.06

22–43

56.6 ± 27.7**

27–144

RI

15.4 ± 10.4

8–47

18.4 ± 13.4

8–40

26.3 ± 21

14–101

OD

15.9 ± 8.3

10–30

25.6 ± 9.5

16–39

44.6 ± 22.3**

21–143

LO %

81.3 ± 4.6

80–85

78.7 ± 9.1

64–85

74 ± 9.9

50–87

BMI

28.5 ± 2.45

26–32

31.03 ± 4.99

24–38

30.5 ± 7.18

22–60

ESS Epworth Sleepiness Scale, AHI apnea–hypopnea index, RI arousal index, OD oxygen desaturation index, LO lowest oxygen saturation on sleep record, BMI body mass index

*p = 0.002 compared to group I and *p = 0.007 compared to group II, **p < 0.000 compared to groups I and II, ***p = 0,049 compare to group II

Discussion

OSAS is the most frequent disorder in sleep-related respiratory diseases. Management modalities of OSAS are CPAP, oral appliances, and surgery in certain conditions such as tonsillar hypertrophy and septal deviation [1, 2, 7, 8]. Another surgical approach is maxillomandibular advancement operation [9]. Previous studies have emphasized that CPAP is cornerstone in OSAS management [4, 911]. Although effective, continuous positive airways pressure requires regular use, and many people cannot tolerate it or do not use it every night. Some studies have reported that excessive daytime symptoms, such as sleepiness and neurocognitive changes, affect the CPAP compliance [9, 12, 13]. We used the ESS to evaluate excessive daytime symptoms, which was significantly higher in patients using CPAP regularly. We found that both OD and AHI were significantly higher in the group of patients who used CPAP regularly comparing to the cases who used occasionally and who never used. BMI and the lowest oxygen saturation did not seem to affect compliance to CPAP treatment. Considering the positive correlation of treatment compliance with AHI, OD, and ESS, we suggest that as the severity of OSAS increases, the level of compliance increases as well. The possible reasons for ineffective CPAP use in patients with less severe OSAS may be the lesser impaired neurocognitive functions and daytime symptoms, which, in turn, might result in decreased sense of satisfaction from the treatment.

In conclusion, we found that patients with less severe OSAS do not satisfactorily adhere to the CPAP treatment. In this particular group of patients, increased risk of treatment failure and bad prognosis is likely. Considering the well-established benefits of CPAP treatment in patients with true indications, patients should be encouraged to use CPAP regularly, and complications of OSAS should be keynoted. Further studies are needed to explore factors affecting compliance with CPAP treatment and long term results of bad adherence to CPAP trteatment in severe and less severe OSAS cases.

Copyright information

© Springer-Verlag 2008