Obstructive Sleep Apnoea and Difficult Asthma (OSADA)

Many people with asthma that remains difficult to control despite standard medications also have obstructive sleep apnoea (OSA) — a condition where the airway repeatedly collapses during sleep, causing oxygen dips and fragmented rest. The OSADA trial is testing whether finding and treating OSA with CPAP (a mask that keeps the airway open during sleep) can meaningfully improve asthma control in this hard-to-treat group. Participants first complete a home sleep study; those found to have OSA are then randomly assigned either to receive CPAP or to go untreated, while a third group of patients without OSA serves as a reference. The primary question is whether CPAP-treated patients show better asthma control, fewer symptoms, and improved quality of life compared with untreated OSA patients. Secondary outcomes track exacerbation rates, sleep quality, and how often patients need healthcare. The trial is currently recruiting at St. James's Hospital in Ireland, with a completion date anticipated around May 2026. If CPAP treatment does improve asthma outcomes, the findings would support integrating sleep medicine screening into standard difficult-asthma care pathways — a potentially low-cost intervention for a high-burden population.

• Trial is currently recruiting; no efficacy results are yet available — all findings below reflect pre-specified objectives and design rationale.
• Primary endpoint: change in validated asthma control score (e.g., ACQ or ACT) between CPAP-treated OSA, untreated OSA, and OSA-free reference groups — specific thresholds not yet reported.
• Secondary endpoints include asthma exacerbation frequency, patient-reported sleep quality, and healthcare utilisation metrics, providing a multidimensional picture of the OSA–asthma interaction.

OSADA is an open-label, three-arm randomised controlled trial enrolling adults with difficult-to-control asthma at St. James's Hospital, Dublin, Ireland. All participants undergo home-based polysomnography or respiratory polygraphy to screen for OSA; those positive for OSA are randomised 1:1 to CPAP therapy (intervention) or no OSA treatment (control), with OSA-negative patients forming a non-randomised reference arm. The open-label design means neither participants nor clinicians are blinded to treatment allocation, which is a recognised pragmatic choice for device-based interventions. Sample size and follow-up duration are not yet disclosed in the registry record; trial completion is projected for May 2026.

Because the trial is open-label, placebo or sham-CPAP effects cannot be separated from true physiological benefit, potentially inflating patient-reported outcomes in the treated arm. The three-arm design (two randomised, one non-randomised reference) means the OSA-negative group is not comparable by random allocation, limiting causal inference about OSA prevalence effects per se. The study does not yet report biomarker or mechanistic endpoints (e.g., airway inflammation markers, cytokine profiles), so it cannot distinguish whether any asthma improvement is driven by reduced intermittent hypoxia, better sleep architecture, or reduced systemic inflammation. A future mechanistic sub-study measuring inflammatory mediators — analogous to the immune-pathway work seen in related OSA research — would help clarify the biological pathway.

OSADA extends [§96], which examines neurocognitive and health outcomes of sleep apnoea in patients with another obstructive lung disease (COPD), by shifting the comorbidity focus to difficult asthma and adding a randomised CPAP intervention arm rather than observational follow-up alone. The trial also parallels [§110], which investigates how intermittent hypoxia — the defining physiological insult of OSA — alters loop gain and respiratory control in healthy subjects, providing a mechanistic backdrop for why untreated OSA might destabilise asthmatic airways. A further mechanistic parallel exists with [§109], whose work on macrophage polarisation via JAK2/STAT3 signalling in OSA-related metabolic disease suggests that the immune consequences of sleep-disordered breathing could plausibly amplify type-2 airway inflammation, a hypothesis OSADA's secondary outcomes may indirectly test. Additionally, [§112] — demonstrating that melatonin suppresses ILC2-driven airway hyperreactivity — hints that the circadian and hypoxic disruption caused by OSA may have direct immunological relevance to asthma pathobiology, contextualising OSADA within a broader circadian-immune framework.

• Neurocognitive and Health Impact of Sleep Apnea in Elderly Veterans With Comorbid COPD
  Closest structural parallel: also an interventional study examining how treating OSA affects respiratory disease outcomes in a pulmonary comorbidity population (COPD), making direct methodological comparison informative.
• Influence of Intermittent Hypoxia on Loop Gain in Healthy Subjects
  Provides the mechanistic foundation for OSADA — intermittent hypoxia from OSA alters respiratory loop gain, which may directly worsen airway instability in asthma patients.
• METTL14 Regulates Adipose Tissue Macrophage Polarization via JAK2 / STAT3 Pathway to Attenuate Obstructive Sleep Apnea‐Related Systemic Inflammation
  OSA-driven macrophage polarisation via JAK2/STAT3 offers a candidate immune pathway through which untreated OSA could amplify asthmatic airway inflammation, framing OSADA's biological rationale.
• Melatonin suppresses ILC2-driven airway hyperreactivity via glutathione-dependent metabolic reprogramming
  Demonstrates that ILC2-mediated airway hyperreactivity — a core asthma mechanism — is modifiable via circadian/metabolic pathways, suggesting OSA-induced circadian disruption may be a direct upstream driver of difficult asthma.
• Sleep, Light, Circadian, Central Oxidative Stress
  Examines how sleep deficiency drives systemic oxidative stress and immune dysregulation, providing a broader biological context for the immune and inflammatory consequences of poor sleep in OSADA's patient population.