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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Reflux in obstructive sleep apnea
Scientific title
Mechanisms of gastroesophageal reflux in obstructive sleep apnoea
Secondary ID [1] 280356 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obstructive sleep apnoea 286320 0
Gastroesophageal reflux 286321 0
Obesity 286322 0
Condition category
Condition code
Respiratory 286567 286567 0 0
Sleep apnoea
Oral and Gastrointestinal 286594 286594 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Study type
Description of intervention(s) / exposure
The proposed research will investigate the underlying reason for the presence of increased gastroesophageal reflux (GOR) in individuals with obstructive sleep apnoea (OSA) and the effect of OSA treatment on nighttime GOR. In order to examine the role of obesity and arousal from sleep in the presence/severity of nighttime GOR, participants will will undergo in laboratory polysomnography, a 24-hour oesophageal pH-impedance recording and a full body dual energy x-ray absorptiometry scan. In order to examine the effect of CPAP on nighttime GOR in those with and without OSA, participants will undergo 2 consecutive sleep studies and a 48-hour oesophageal pH recording (wireless capsule based measurement, placed during gastroscopy). One of the sleep studies will be with CPAP therapy (set at 10cmH20), and the other night without CPAP. This order will be randomised.

Involvement in the study will span up to 72 hours total.

Intervention code [1] 284721 0
Treatment: Devices
Comparator / control treatment
No control group. However group comparisons will be made - including between obese and non-obese individuals, those with and without OSA those with and without nighttime GOR.
Control group

Primary outcome [1] 286994 0
Presence and severity of GOR assessed by pH/impedance testing.
Variables assessed will include: acid contact time, number of acidic and non-acidic reflux events, longest event and number of events > 5 mins.
Timepoint [1] 286994 0
These will be assessed over the 24-hour period as a whole and divided into 'wake time' and 'sleep time' (8 hour sleep study).
Primary outcome [2] 307358 0
Measures of sleep quality and OSA severity as assessed by polysomnography.
Variables include: number of apnoeic/hypopnoeic events, number of arousals and relationship of each arousal to reflux and respiratory events.
Comparisons will be made between groups with and without nighttime GOR and between nights off and on CPAP. The principal analyses for these comparisons will be unpaired or paired t-test.

Timepoint [2] 307358 0
Analyses will be conducted over the 8 hour sleep study.
Secondary outcome [1] 297164 0
Post-hoc analyses will be conducted to determine if the presence and severity of hiatus hernia influences the presence of nighttime GOR or the effect of CPAP on GOR. Presence of hiatus hernia will be detectable during gastroscopy for insertion of the Bravo capsule.
Timepoint [1] 297164 0
Presence of hiatus hernia will be detectable during gastroscopy for insertion of the Bravo capsule.

Key inclusion criteria
18-70 years of age of mixed gender with no significant co-morbidity..

Participants were recruited from patients who had undergone a gastroscopy for investigation of GOR symptoms in the previous 12 months.
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Uncontrolled hypertension, ischaemic heart disease, type I diabetes or depression.
Previous oesophageal or gastric surgery
Gastroesophageal disorders such as lupus, coeliac disease or ulcerative colitis.

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Each subject will undergo two conditions - one night of no CPAP and one night of CPAP in a randomised fashion. Therefore there is no need for a procedure for allocating treatment.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
An online number sequence generator was used with numbers randomly selected from within the range of 0 to 1. Duplicate numbers were allowed. This table was generated on 1/18/2015.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 285133 0
Government body
Name [1] 285133 0
National Health and Medical Research Council
Address [1] 285133 0
GPO Box 1421
Canberra ACT 2601
Country [1] 285133 0
Primary sponsor type
University of Western Australia
35 Stirling Highway
Crawley WA 6009
Perth, Australia
Secondary sponsor category [1] 283998 0
Name [1] 283998 0
Sir Charles Gairdner Hospital
Address [1] 283998 0
Hospital Avenue, Nedlands WA 6009
Country [1] 283998 0

Ethics approval
Ethics application status
Ethics committee name [1] 287149 0
Sir Charles Gairdner Group Human Research Ethics Committee
Ethics committee address [1] 287149 0
2nd Floor A Block (Mailbox 26)
Sir Charles Gairdner Hospital
Hospital Ave
Nedlands, WA
Ethics committee country [1] 287149 0
Date submitted for ethics approval [1] 287149 0
Approval date [1] 287149 0
Ethics approval number [1] 287149 0

Brief summary
This research will define the mechanisms underlying the presence of gastroesophageal reflux (GOR) in individuals with obstructive sleep apnoea (OSA). Both are common conditions with OSA affecting 1 in 20 individuals and GOR affecting approximately 1 in 12 individuals in the community. Continuous positive airways pressure (CPAP), the most common and effective treatment for OSA has also been found to treat GOR.

GOR symptoms are more common in OSA than the general population (14% vs 5%) and increase with increasing OSA severity. Nighttime GOR is a particular worry in individuals with OSA with 1 in 3 OSA patients reporting overnight symptoms. GOR has significant negative health effects in individuals with OSA including painful symptoms and an increase in cancer risk. Identification of the reasons for the increased incidence of reflux in OSA may assist in improving prevention and/or treatment of GOR in individuals with OSA as well as increasing quality of life in these patients.

The overall aim of the proposed research is to determine the underlying reason for the presence of gastroesophageal reflux (GOR) in individuals with obstructive sleep apnoea (OSA), including the roles of obesity and arousal from sleep. Furthermore, we aim to determine the effect of OSA treatment with CPAP therapy on nighttime GOR in individuals with and without OSA. .

We aim to recruit a total of 80 individuals of mixed gender between the ages of 18 and 70 years of age. Each participant will undergo a 24 hour pH-impedance study for assessment of reflux severity, an overnight sleep study and a DXA scan to assess obesity and fat distribution; or a 48hour recording of oesophageal pH with two consecutive overnight sleep studies, of with CPAP therapy and one without, in a randomised fashion.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 34088 0
Prof Peter Eastwood
Address 34088 0
Department of Pulmonary Physiology and Sleep Medicine Internal Mailbox 201 Queen Elizabeth II Medical Centre Hospital Ave Nedlands Western Australia 6009
Country 34088 0
Phone 34088 0
+61 (08) 6457 1706
Fax 34088 0
Email 34088 0
Contact person for public queries
Name 17335 0
Dr Kelly Shepherd
Address 17335 0
Department of Pulmonary Physiology and Sleep Medicine
Internal Mailbox 201
Queen Elizabeth II Medical Centre
Hospital Ave
Western Australia
Country 17335 0
Phone 17335 0
+61 (08) 6457 3056
Fax 17335 0
+61 (08) 6457 2034
Email 17335 0
Contact person for scientific queries
Name 8263 0
Dr Kelly Shepherd
Address 8263 0
Department of Pulmonary Physiology and Sleep Medicine
Internal Mailbox 201
Queen Elizabeth II Medical Centre
Hospital Ave
Western Australia
Country 8263 0
Phone 8263 0
+61 (08)9346 3056
Fax 8263 0
+61 (08)9346 2034
Email 8263 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary