Mixed Method Model to Assess CPAP Adherence Among Patients with Moderate to Severe OSA

Abstract

Background. Continuous positive airway pressure (CPAP) is an effective therapy for obstructive sleep apnoea (OSA). Despite proven benefits of CPAP in OSA, adherence has been sub-optimal. The present study was designed to evaluate the compliance of CPAP therapy and factors affecting it in patients with moderate to severe OSA.

Full text

Original Article
Mixed Method Model to Assess CPAP Adherence Among Patients with
Moderate to Severe OSA
Priya Ramachandran1, Uma Devaraj1, Sandeepa HS2, Kavitha V1, Uma Maheswari K1 and George D’Souza1
Department of Pulmonary Medicine1, St. John’s Medical College Hospital, Bangalore and BGS Global Hospital2,
Bangalore, India
Abstract
Background. Continuous positive airway pressure (CPAP) is an eective therapy for obstructive sleep apnoea (OSA). Despite
proven benets of CPAP in OSA, adherence has been sub-optimal. The present study was designed to evaluate the compliance
of CPAP therapy and factors aecting it in patients with moderate to severe OSA.
Methods. Patients diagnosed to have moderate/severe OSA (apnoea-hypopnoea index [AHI] >15) during the period April to
December 2015 were evaluated using a pre-dened questionnaire on the number of hours of usage, number of nights per week
usage and challenges faced in using CPAP; Epworth Sleepiness Score was recorded. CPAP usage was documented from the
downloaded data from their CPAP machines.
Results. Forty patients (mean age 50.6±11.4 years; 29 men) were studied. Their average body mass index (BMI) was 33.2 Kg/m2.
Of these, 31 had severe OSA (mean AHI 47.8 per hour). The objective usage of CPAP among patients with OSA was less by 89
minutes when compared with perceived duration (p=0.001). Twenty patients had used the device for less than four hours per
night. Patients reported social factors, dryness of mouth, not reapplying machine aer nocturia, power shut down and reduced
motivation as reasons for non-adherence to use CPAP.
Conclusions. Despite the recognised benets of CPAP, the acceptance and adherence with therapy remains a considerable
barrier. Objective assessment of CPAP compliance should be a part of routine follow-up in patients with OSA.
[Indian J Chest Dis Allied Sci 2019;61:119-122]
Key words: Obstructive sleep apnoea, CPAP, Compliance, Adherence.
Introduction
Obstructive sleep apnoea (OSA) is a disorder that is
portrayed by abnormal collapse of the pharyngeal airway
during sleep leading to apnoeic episodes and repetitive
arousals from sleep.1 Apnoea-hypopnoea index (AHI) is
the measure of total number of apnoea and hypopnoea
events per hour of sleep.2 An AHI of ve or greater
in combination with self-reported hyper-somnolence
is indicative of clinically symptomatic sleep apnoea
syndrome. Sleep apnoea syndrome is associated with
cardiovascular diseases, such as hypertension, angina,
arrhythmias, coronary heart disease and congestive heart
failure.3 In community-based studies even mild occult sleep
apnoea is associated with hypertension, excessive day-time
somnolence, morning headaches, mental and cognitive
impairments, erectile dysfunction, bromyalgia and higher
rates of automobile and work related accidents.4
Continuous positive airway pressure (CPAP) is an
eective therapy for OSA.5 CPAP use reduces day-time
sleepiness, enhances daily function, elevates mood, reduces
automobile accidents and decreases blood pressure and
other cardiovascular events.6 Despite proven benets of
CPAP in OSA syndrome, and an initial acceptance rate
of 70% to 80%7, the adherence has been shown to be sub-
optimal.8 It is estimated that 29% to 83% of patients are
non-adherent to CPAP therapy (CPAP use ≤4 hours of
use per night).9 In a recent study,10 CPAP adherence was
evaluated to be 30.3% and inability to buy the CPAP device
was quoted as the main barrier to adherence. Sparse data is
available on the causative factors leading to non-adherence
to CPAP. Hence, we designed this study to evaluate the
compliance to CPAP therapy and factors aecting CPAP
compliance.
Material and Methods
Adult patients above the age of 18 years, diagnosed to
have moderate/ severe OSA (AHI >15) from April 2015 to
December 2015 were contacted through telephone. The
study was initiated aer Institutional Ethics Commiee
approval. Patients who gave history of CPAP use for a
duration of a month or more were invited to participate
in the study. The subjects were recently diagnosed and
were using the CPAP for a duration of 3-10 months. The
[Received: May 14, 2018; accepted aer revision: August 14, 2018]
Correspondence and reprint requests: Dr Uma Devaraj, 3rd Floor, PFT Lab, Oncology Block, St. John’s Medical College, Sarjapur
Road, Bangalore-560 034 (Karnataka), India; E-mail: druma.devaraj@gmail.com
2

120
subjects were enquired about the compliance of CPAP
therapy, and were invited to visit the sleep clinic. A wrien
informed consent was taken and subjects’ identity was
coded, ensuring condentiality and anonymisation of data.
During this visit the subjects received a brief explanation
of OSA and the use of CPAP regularly, by the sleep
physician. Demographic details, like age, gender, body-
mass index (BMI) and presence of comorbid conditions
were noted. A pre-dened questionnaire which included
questions on number of hours of use of CPAP, CPAP used
for number of nights per week, the challenges in using
CPAP (each parameter was rated on a 5 point Likert scale)
and Epoworth Sleepiness Score (ESS) was administered.
The use of CPAP machine was noted from the downloaded
data from their CPAP machines.
Statistical Analysis
Categorical variables were described by frequencies and
proportions; continuous variables were compared by
“student t” test or Wilcoxon rank sum where appropriate,
and for comparing proportions Chi-square or Fisher’s
exact test was used. Multivariable logistic regression, with
dependent variable as number of minutes of CPAP use per
night and the independent variables being age, gender,
BMI, AHI and co-morbidities, was done to observe the eect
of variable factors on CPAP compliance. Analysis was done
using statistical soware Statistical Package for the Social
Sciences (SPSS) (Version 17, Chicago, IL). A two-tailed p
value of <0.05 was considered statistically signicant.
Results
A total of 121 patients were contacted through telephone.
Forty patients had consented to participate in the study.
Their mean age was 50.6±11.4 years; there were 29 men
(Table 1). Ischaemic heart disease and hypothyroidism
were present in three patients each. The mean duration of
usage as reported by the patients was 322.5 minutes. On
analysing the download data of the CPAP machine, the
mean duration of usage was 233 minutes. There was a
dierence of 89 minutes between the perceived duration
and the actual usage of CPAP machine among patients
studied for OSA (p=0.001, 95% condence intervals [CI],
-96.71 to -37.73). Of the 40 patients studied, 20 had used the
device for less than four hours per night and three patients
reported using CPAP for four or less number of days per
week. Thus, only 17 of the 40 (42.5%) patients studied were
compliant with CPAP therapy. Thirteen patients did not
reconnect CPAP in the night if there was awakening (for
micturition).
Median use of CPAP was 230 minutes in women
as compared to 270 minutes in men. Women were 2.16
(95% CI, 0.7-6.62) times more likely to be non-adherent
than men. None of the factors, such as age, BMI, AHI
and co-morbidities show any signicant eect on CPAP
compliance in the subjects.
There was no dierence in compliance when
considering the mask interface (nasal [n=23] versus full-face
mask [n=17]); rental device (n=5) versus own CPAP device
(n=35). Manual (n=23) versus auto CPAP (n=17) also did not
determine the adherence to CPAP in these patients.
The challenges in using CPAP (each parameter was
rated on a 5 point Likert scale) are given in table 2.
Table 2. Factors for non-compliance
Factor Yes No
Ill-ing mask 14 26
Leak 14 26
Nasal stuness 18 22
Headache 7 33
Noise 7 34
Dryness of mouth 29 11
Gastric distension 8 32
anxiety 3 27
Interruption of power 3 27
Social inhibition 20 20
Skin Changes 139
Discussion
Obstructive sleep apnoea is a non-communicable disease
with considerable prevalence rate of 13.4%.11 It is well
known that CPAP therapy is eective only when the
device is applied and there are no long lasting eects.
Hence, adherence to CPAP is vital for the treatment to be
eective. Adherence to CPAP therapy has been appalling
at 50%8 to 70%,12 also considering a 25% drop-out rate
in the long term.13 A vast dierence between subjective
adherence (85.1%) and objective adherence (64.5%) has
been reported.14 They have also noted a poor follow-up rate
of 38.3%, which might have contributed to the observed
adherence levels.
Adherence to CPAP Therapy in Patients with OSA Priya Ramachandran et al
Table 1. Patient’s characteristics
Characteristics Result (N=40)
Age (years) 50.6±11.4
Male: Female 29:11
Mean BMI (Kg/m2)33.2
Severe OSA 31
Mean AHI (per hour) 47.8
Smokers 14
Alcohol use 10
Diabetes 23
Hypertension 32
Denition of abbreviations: BMI=Body mass index; OSA=Obstructive
sleep apnoea; AHI=Apnoea-hypopnoea index

2019; Vol. 61 121The Indian Journal of Chest Diseases & Allied Sciences
Though India has a huge burden of OSA, and patients
diagnosed as OSA are initiated on treatment, there is sparse
data on how many patients actually use the CPAP therapy
as recommended. To the best of our knowledge, this is the rst
study to explore the subjective and objective assessment of
CPAP compliance in India.
In the present study, 42.5% of the patients studied
showed adherence to CPAP therapy. Some distinctive
factors emerged as obstacles to CPAP adherence. Dryness
of mouth, nasal stuness, ill-ing mask and leak from
the mask end were cited as common reasons for the non-
compliance. Twenty-nine and 18 subjects aributed their
non-compliance to dryness of mouth and nasal stuness,
respectively. Subjects reported CPAP non-compliance when
relatives or friends came to visit them, or when they were
travelling. Surprisingly, embarrassment to use the CPAP
due to social inhibition reported by 50% of the subjects. So
far there are no previous reports which have looked into
the social aspects of CPAP therapy.
Previous systematic review by Andrade et al15 have
concluded lower adherence and higher CPAP abandonment
with oro-nasal masks than the nasal masks. On the contrary,
our patients did not show a dierence in adherence when
comparing those using nasal mask versus oro-nasal mask.
This is probably due to the small number of subjects in the
present study.
Headache, excessive noise and gastric distension are the
other frequently cited reasons for non-compliance; these
have been quoted as causes for non-compliance to a similar
extent in previous studies.1,2 CPAP usage has been linked
to reduction of headaches in 30% of patients.16 However,
seven reported reduced compliance due to headache.
Many patients had related headache to the pressure on the
face due to the mask interface.
Three subjects each related power shut down and
reduced motivation as the main reason for non-adherence.
Thus far, power shut down as a reason for non-compliance
has not been reported, signifying the unique situation
where a sophisticated machine is available as therapy
but the power supply to operate the same is sometimes
lacking.
Regular CPAP use is known to reduce the mean number
of nocturia incidents by 2.3.17 Not only the frequency of
urination but volume of urination is also reduced with
CPAP use. In our subjects, though many commenced sleep
with CPAP machine, some reported of not reapplying the
machine aer geing up for urination. In elderly men,
concomitant benign prostatic hypertrophy (BPH) should
be appropriately considered, investigated and treated as a
cause of nocturnal polyuria.
None of our subjects reported claustrophobia as a
reason for CPAP non-compliance which was unforeseen,
whereas Edmond et al18 have noted claustrophobia in 63%
of their subjects. Claustrophobic subjects were twice likely
to be non-adherent to CPAP as compared to those without
claustrophobia. Targeted interventions aer identication
of subjects with claustrophobia tendencies may improve
CPAP adherence.18,19
A standardised assessment for insomnia, which is a
known factor that impacts adherence, was not performed.
The number of subjects in this study was small, hence
excludes any risk factor stratication between compliant
and non-compliant subjects. Along with this, medications
of interest, especially non-benzodiazepine receptor agonist,
which can improve adherence were not reported, which
are the limitations of this study.
Conclusions
Salient features evident from this study are that minor factors,
such as nasal stuness, dryness of mouth, travelling/social
factors are major hurdles for adherence to CPAP therapy. With
advancement in device designs, modes of CPAP delivery and
beer and comfortable mask interface, CPAP compliance
can be improved. Regular counselling about the disease,
impact of consistent CPAP use will improve the motivation
for CPAP adherence. There is a signicant dierence in the
perceived duration of usage and the actual usage of CPAP
among patients with OSA. Objective assessment of CPAP
compliance should be a part of routine follow-up in patient
with OSA. A roadmap comprising solutions to the commonly
faced challenges, such as nasal stuness, mask leak should
be devised to improve the compliance. Hitherto unexplored
factors, such as social inhibition and power disruptions have
emerged as a cause of non-compliance. Further studies are
required to assess the factors aecting CPAP compliance
among patients with OSA.
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