An observational study in Obstructive Sleep Apnoea (OSA), sponsored by King's College London. Active, not recruiting at 2 sites in United Kingdom. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-10.
Sponsored by King's College London · Observational
This observational study is being undertaken as a part of a Master of Research (MRes) in Clinical Research programme.
Its goal is to learn about how continuous positive airway pressure (CPAP) therapy changes the complexity of body signals in adults with obstructive sleep apnoea (OSA). The main question it aims to answer is:
- How does the complexity of physiological signals (specifically oxygen saturation, heart rate, and heart rate variability) change in adults with OSA from before to after three and six months of CPAP treatment?
It will use data from individuals who took part in an earlier trial, called 3DPiPPIn, which tested the use of 3D-printed, customised masks CPAP masks through sleep studies.
The purpose of this MRes student study is primarily to examine how the entropy, or complexity as measured by entropy, of physiological signals changes in patients with obstructive sleep apnoea (OSA) in response to continuous positive airway pressure (CPAP) therapy.
It is a secondary analysis of data from 3DPiPPIn, a randomised control trial investigating the feasibility of using 3D-printing to develop customised masks for patients receiving positive airway pressure (PAP) therapy.
The hypothesis for this study is that entropy-based measures derived from physiological signals will exhibit changes following CPAP therapy, when compared to pre-therapy measures, reflecting the modulation and restoration of physiological systems that were previously disrupted by OSA.
2,198 studies on the registry are indexed under Sleep Apnea, Obstructive; 468 are open to participants now.
This study's planned enrollment of 139 is above the median of 104 across 648 observational studies indexed under Sleep Apnea, Obstructive.
Browse Sleep Apnea, Obstructive studies →King's College London is the lead sponsor of 507 studies on the registry; 125 are open to participants now.
Counted across the registry records on this site, refreshed daily.
PAP-naive adults with obstructive sleep apnea (OSA), identified from the Sleep and Ventilation Service at Royal Free London NHS Foundation Trust, who participated in the 3DPiPPIn randomised controlled trial.
Exclusion Criteria:
Participants were originally recruited to the 3DPiPPIn trial from the Sleep and Ventilation Service at Royal Free London NHS Foundation Trust. The cohort for this secondary analysis comprises adults with sleep-disordered breathing and an Apnoea-Hypopnoea Index (AHI) \>15 events/hour who required but had never received PAP therapy, drawn from the trial participants who provided consent for their data to be used in future research.
Device: Continuous Positive Airway Pressure Therapy
The intervention of interest within this secondary analysis study is Continuous Positive Airway Pressure (CPAP) Therapy, a device-based treatment used to maintain airway patency in patients with sleep-disordered breathing. As a retrospective study, participant exposure to CPAP occured exclusively within the original 3DPiPPIn trial.
Also known as: CPAP, CPAP Therapy, PAP, PAP Therapy, Positive Airway Pressure Therapy
Change in oxygen saturation entropy from pre to six months post CPAP therapy
Time frame: From baseline to six months post-initiation of CPAP therapy
Change in heart rate entropy from pre to six months post CPAP therapy
Time frame: From baseline to six months post-initiation of CPAP therapy
Change in heart rate variability entropy from pre to six months post CPAP therapy
Time frame: From baseline to six months post-initiation of CPAP therapy
Change in oxygen saturation entropy from pre to three months post CPAP therapy
Time frame: From baseline to three months post-initiation of CPAP therapy
Change in heart rate entropy from pre to three months post CPAP therapy
Time frame: From baseline to three months post-initiation of CPAP therapy
Change in heart rate variability entropy from pre to three months post CPAP therapy
Time frame: From baseline to three months post-initiation of CPAP therapy
Relationship between residual Apnoea-Hypopnoea Index and oxygen saturation entropy
The Apnoea-Hypopnoea Index (AHI) is the total number of apnoea and hypopnoea events per hour of sleep. The minimum value is 0 events/hour, and there is no fixed maximum value. Higher scores indicate more severe sleep-disordered breathing (worse outcome).
Time frame: From baseline to three and/or six months post-initiation of CPAP therapy
Relationship between residual Apnoea-Hypopnoea Index and heart rate entropy
The Apnoea-Hypopnoea Index (AHI) is the total number of apnoea and hypopnoea events per hour of sleep. The minimum value is 0 events/hour, and there is no fixed maximum value. Higher scores indicate more severe sleep-disordered breathing (worse outcome).
Time frame: From baseline to three and/or six months post-initiation of CPAP therapy
Relationship between residual Apnoea-Hypopnoea Index and heart rate variability entropy
The Apnoea-Hypopnoea Index (AHI) is the total number of apnoea and hypopnoea events per hour of sleep. The minimum value is 0 events/hour, and there is no fixed maximum value. Higher scores indicate more severe sleep-disordered breathing (worse outcome).
Time frame: From baseline to three and/or six months post-initiation of CPAP therapy
Relationship between Epworth Sleepiness Scale scores and oxygen saturation entropy
The Epworth Sleepiness Scale (ESS) is a self-administered questionnaire that measures daytime sleepiness. Scores range from 0 to 24, with higher scores indicating greater daytime sleepiness (worse outcome).
Time frame: From baseline to three and/or six months post-initiation of CPAP therapy
Relationship between Epworth Sleepiness Scale scores and heart rate entropy
The Epworth Sleepiness Scale (ESS) is a self-administered questionnaire that measures daytime sleepiness. Scores range from 0 to 24, with higher scores indicating greater daytime sleepiness (worse outcome).
Time frame: From baseline to three and/or six months post-initiation of CPAP therapy
Relationship between Epworth Sleepiness Scale scores and heart rate variability entropy
The Epworth Sleepiness Scale (ESS) is a self-administered questionnaire that measures daytime sleepiness. Scores range from 0 to 24, with higher scores indicating greater daytime sleepiness (worse outcome).
Time frame: From baseline to three and/or six months post-initiation of CPAP therapy
Nocturnal hypoxia (T90%)
T90% will be calculated as the percentage of total sleep time during which oxygen saturation is below 90%. T90 values will be categorised according to predefined thresholds to characterise the severity of nocturnal hypoxia.
Time frame: At baseline, three months and/or six months post-initiation of CPAP therapy
Plan to share: No — The data used in this secondary analysis include potentially re-identifiable patient information. In line with the open access approach of the study's parent trial, 3DPiPPIn, individual participant data will not be shared to protect participant confidentiality.
This study is active, not recruiting, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
King's College London