Condition category
Signs and Symptoms
Date applied
04/10/2016
Date assigned
12/10/2016
Last edited
13/10/2016
Prospective/Retrospective
Retrospectively registered
Overall trial status
Completed
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Obstructive sleep apnoea (OSA) is a common condition in which the upper airways (wind pipe) collapse repeatedly during sleep, stopping the flow of air into the lungs. This prevents the sufferer from being able to breathe properly while they are asleep, causing excessive sleepiness throughout their waking hours. OSA is usually treated using a continuous positive airway pressure (CPAP) machine. This involves the patient wearing a face mask during sleep which is connected to the machine which supplies a constant steam of air to help keep the airways open. Although this therapy has been using for decades now, it is not known whether it affects a patient’s sense of smell. This study consists of two parts, in the first part the aim of this study is to find out whether sense of smell changes as a result of undergoing CPAP as part of standard care. In the second part, participants receiving CPAP are randomly allocated to continue with treatment or have the pressure of the device lowered (so it is no longer as effective) in order to see if this impacts on sense of smell.

Who can participate?
Adults with moderate to severe OSA who suffer from daytime sleepiness

What does the study involve?
In the first part of the study participants attend a study visit at which they complete a questionnaire about their sleepiness and sense of smell. Their sense of smell is then tested by asking participants to smell a number of scent dispensing smells. Following this, participants begin standard CPAP therapy as part of their usual care. Three months later, participants attend a second study visit at which time the questionnaires and smell tests are repeated in order to find out if CPAP has had an effect on their sense of smell and how tired they are during the day.
In the second part of the study, participants able to stick to the CPAP therapy in the first part of the study are randomly allocated to one of two groups. Those in the first group continue with their standard CPAP therapy for three weeks, those in the second group have the pressure of the CPAP device lowered for three week so it is no longer working as well. At the start of this treatment period and then after three weeks, participants complete questionnaires and smell tests in order to assess their sense of smell and how tired they are during the day.

What are the possible benefits and risks of participating?
There are no direct benefits or risks involved for those participating in this study.

Where is the study run from?
Cantonal Hospital Aarau (Switzerland)

When is the study starting and how long is it expected to run for?
February 2014 to August 2016

Who is funding the study?
Research Council of the Cantonal Hospital Aarau (Switzerland)

Who is the main contact?
Dr Sarosh Irani
siran@gmx.ch

Trial website

Contact information

Type

Scientific

Primary contact

Dr Sarosh Irani

ORCID ID

Contact details

Clinic of Pulmonary and Sleep Medicine
Cantonal Hospital Aarau
Tellstrasse 25
Aarau
CH-5001
Switzerland
+41 62 838 44 70
siran@gmx.ch

Additional identifiers

EudraCT number

ClinicalTrials.gov number

Protocol/serial number

EKNZ 2014-335

Study information

Scientific title

Significant improvement of olfactory performance in sleep apnea patients after three months of nasal continuous positive airway pressure therapy

Acronym

Study hypothesis

The aim of this study is to assess the sense of smell before initiation of nasal continuous positive airway pressure (CPAP) and after three months treatment, in moderate and severe obstructive sleep apnea (OSA) patients.

Ethics approval

Ethics Committee of the Nordwest- und Zentralschweiz, 18/11/2014, ref: EKNZ 2014-335
Amendment approved: 19/05/2016

Study design

Part 1: Observational cohort study
Part 2: Randomised controlled trial

Primary study design

Observational

Secondary study design

Cohort study

Trial setting

Hospitals

Trial type

Treatment

Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet

Condition

Olfactory performance in moderate and severe sleep apnea patients

Intervention

Part 1:
Participants attend a study visit at which they undergo several investigations. Firstly, a questionnaire concerning sleepiness and self-estimated quality of the own olfaction has to be answered which takes about five minutes. Secondly, sense of smell is tested with the aid of a standardized test battery. This test battery contains 112 odour-dispensing pens to evaluate odour threshold, odour discrimination and odour identification. These pens are exposed to the nose of the patient in a specific order. The test takes about 40 minutes.
During the same visit patients then begin standard CPAP therapy as part of their usual care. This involves adaptation of a suitable nasal mask and instruction of the patient how to use and to maintain the CPAP device and the humidifier.

After three months, participants attend another study visit at which they undergo the same procedure of testing the sense of smell and answering the same questionnaire as during the initial study visit. Furthermore, after these tests a download of the therapy data are discussed with the patient and a check of the CPAP device is performed. This follow up visit takes about 90 minutes.

Part 2:
Participants who show a sufficient therapy adherence during the first follow up visit are randomized to one of two groups using block randomization if they agree to take part to the second study part and give written informed consent. Sufficient therapy adherence is defined as applying the CPAP therapy in 70% of the nights at least 4 hours CPAP use per night.

Group 1: Patients maintain under unchanged CPAP therapy for three weeks (maintenance group)
Group 2: Therapy pressure of the CPAP device is set to a sub therapeutic pressure of 4 centimeter of water for three weeks (sham group).

Follow up for all participants involves testing of sense of smell and answering the study questionnaire much like they did at the follow up visit. The visits take place at the outpatients department of the Cantonal Hospital Aarau, Switzerland.

Intervention type

Device

Phase

Drug names

Primary outcome measures

Part 1:
Self-estimated olfaction is measured using a visual analogue scale (VAS) at baseline and 3 months.

Part 2:
Self-estimated olfaction is measured using a visual analogue scale (VAS) at baseline and 3 weeks.

Secondary outcome measures

Part 1:
1. Odor threshold, odor discrimination, odor identification and the summarized value of these three tests threshold, discrimination and identification overall score (TDI) are measured with the aid of a standardized test battery (sniffin’sticks) at baseline and 3 months
2. Daytime sleepiness is measured using the Epworth sleepiness scale (ESS) at baseline and 3 months

Part 2:
1. Odor threshold, odor discrimination, odor identification and the summarized value of these three tests threshold, discrimination and identification overall score (TDI) are measured with the aid of a standardized test battery (sniffin’sticks) at baseline and 3 weeks
2. Daytime sleepiness is measured using the Epworth sleepiness scale (ESS) at baseline and 3 weeks

Overall trial start date

05/02/2014

Overall trial end date

16/08/2016

Reason abandoned

Eligibility

Participant inclusion criteria

1. Outpatients of our department of pulmonary and sleep medicine
2. Age 18 years and over
3. Suffer from daytime sleepiness
4. Show moderate to severe OSA (apnea hypopnea index (AHI) ≥ 15 per hour) in a respiratory sleep study

Participant type

Patient

Age group

Adult

Gender

Both

Target number of participants

30 patients

Participant exclusion criteria

1. Lack of written informed consent
2. Insufficient knowledge of the German language
3. Known disease of the nasal cavity or sinuses, or topical nasal therapy usage

Recruitment start date

19/11/2014

Recruitment end date

15/07/2015

Locations

Countries of recruitment

Switzerland

Trial participating centre

Cantonal Hospital Aarau
Clinic of Pulmonary and Sleep Medicine Tellstrasse 25
Aarau
CH-5001
Switzerland

Sponsor information

Organisation

Cantonal Hospital Aarau

Sponsor details

Tellstrasse
Aarau
CH-8057
Switzerland
+41 62 838 44 72
pneumologie@ksa.ch

Sponsor type

Hospital/treatment centre

Website

Funders

Funder type

Research council

Funder name

Research Council of the Cantonal Hospital Aarau

Alternative name(s)

Funding Body Type

Funding Body Subtype

Location

Results and Publications

Publication and dissemination plan

Planned publication of study results in a medical journal.

IPD Sharing plan:
The participant level data will not be made available at the request of the approving ethics committee.

Intention to publish date

31/12/2016

Participant level data

Not expected to be available

Results - basic reporting

See additional file ISRCTN11128866_BasicResults_10Oct2016

Publication summary

Publication citations

Additional files

Editorial Notes

13/10/2016: The basic results summary file has been uploaded.