FIBRotic Interstitial Lung Disease With Nocturnal hypOXaemia and EXercise Induced desaTuRAtion

This work will build upon the FIBRINOX study, previous clinical research conducted by the Guy's and St Thomas' ILD research team. The FIBRINOX study showed that patients with fILD and normal oxygen saturations at rest, but who desaturate whilst asleep or during exercise, have a significantly increased mortality and greater reduction in quality of life compared to patients who do not desaturate at night or during exercise.

The reasons for these differences in mortality and health related quality of life are not known. Data suggests that worsening fILD and the development of pulmonary hypertension, a condition characterised by increased pressure in the pulmonary arteries that is associated with poorer outcomes, may be playing a role.

This clinical research study will recruit approximately 160 patients with a tertiary ILD centre diagnosis of fibrotic interstitial lung disease (fILD). Data from routinely performed investigations as part of tertiary ILD assessment will be systematically recorded.

Investigations will include lung function tests, echocardiography, blood tests, a 6-minute walk test and overnight oximetry. Participants will also complete several quality-of-life questionnaires. These investigations will be performed at baseline, and again at 12 months, with all tests also repeated at 6 months except for an echocardiogram. After the initial 1 year study period, a 3 year post-recruitment mortality and right heart catheter check will be performed using the participants' medical records. Data will be collected from CT scans and right heart catheters if performed during the study period as part of the participants usual clinical care.

This study is designed to establish whether patients with fILD who desaturate during sleep or exercise are more likely to experience functional decline, as well as confirm previous findings of increased mortality and worsening quality of life as demonstrated in the FIBRINOX study. The data generated by this observational study will help generate future hypotheses, research questions and clinical study.

• Prospective (Other): Collection of prospective data all ready available for participant

Primary outcomes

• Change in 6-minute walk distance [52 weeks]: As measured by 6-minute walk test

Secondary outcomes

• Mortality [52 and 156 weeks]: If death occurs during the study period, and the cause of death
• Clinical deterioration [52 weeks]: Defined by: decline in forced vital capacity (FVC) >10% or death
• Decline in FVC [52 weeks]: Decline in forced vital capacity
• Decline in TLCO [52 weeks]: Decline in total diffusing capacity of the lungs for carbon monoxide
• Pulmonary hypertension [52 and 156 weeks]: Right heart catheter confirmed pulmonary hypertension
• Change in arterialised capillary blood gas pO2 [52 weeks]: Arterialised capillary blood gas partial pressure of oxygen
• Change in arterialised capillary blood gas oxygen saturations [52 weeks]: Arterialised capillary blood gas oxygen saturations
• Change in arterialised capillary blood gas pCO2 [52 weeks]: Arterialised capillary blood gas partial pressure of carbon dioxide
• Change in arterialised capillary blood gas HCO3 [52 weeks]: Arterialised capillary blood gas partial pressure of bicarbonate
• Change in arterialised capillary blood gas pH [52 weeks]: Arterialised capillary blood gas pH
• Time to first acute exacerbation of fILD [52 weeks]: The number of days until the participant requires hospital admission for an acute worsening of their respiratory condition, not attributable to other causes
• Rate of acute exacerbation of fILD [52 weeks]: The number of times the participant requires hospital admission for an acute worsening of their respiratory condition, not attributable to other causes
• Change in NT-proBNP/BNP level [52 weeks]: Change in NT-proBNP/BNP level from baseline
• Change in troponin level [52 weeks]: Change in troponin level from baseline
• Change in peak TRV [52 weeks]: Change in peak tricuspid regurgitation velocity (TRV)
• Change in cardiac chamber size/area [52 weeks]: Change in cardiac chamber size/area
• Change in cardiac chamber area [52 weeks]: Change in cardiac chamber area
• Change in RV/LV basal diameter area ratio [52 weeks]: Change in right ventricle to left ventricle basal diameter area ratio
• Change in MPA:AA diameter ratio [52 weeks]: Change in main pulmonary artery to ascending aorta diameter ratio
• Change in TAPSE/sPAP ratio [52 weeks]: Change in tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio
• Change in European Quality of Life 5-Dimensions 5-Levels (EQ-5D-5L) questionnaire score [52 weeks]: Change in score of European Quality of Life 5-Dimensions 5-Levels (EQ-5D-5L) questionnaire
• Change in King's Brief Interstitial Lung Disease (KBILD) questionnaire score [52 weeks]: Change in score of King's Brief Interstitial Lung Disease (KBILD) questionnaire
• Change in Living with Pulmonary Fibrosis (L-IPF) questionnaire score [52 weeks]: Change in score of Living with Pulmonary Fibrosis (L-IPF) questionnaire

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. Patients aged 18 year and over
2. Tertiary MDT diagnosis of FILD with >10% fibrosis on CT chest as determined by the investigator. Underlying diagnoses to include but not limited to: idiopathic pulmonary fibrosis (IPF), non-specific interstitial pneumonitis (NSIP), chronic hypersensitivity pneumonitis (CHP), connective tissue disease-related interstitial lung disease (CTD-ILD), fibrotic organising pneumonia (FOP) and pulmonary sarcoidosis.
3. Able to provide informed written consent

Exclusion Criteria:

1. The use of or any indication for long-term oxygen therapy (LTOT)
2. Known moderate or severe obstructive sleep apnoea with an apnoea/hypopnoea index (AHI) or oxygen desaturation index (ODI) over 15 events per hour
3. Radiological predominance of emphysema compared with fibrosis on CT chest
4. Inability to complete all health status questionnaires as set out in this protocol, with appropriate support
5. A confirmed diagnosis of pulmonary hypertension
6. Significant cardiovascular comorbidity including severe, uncontrolled hypertension, uncontrolled arrhythmia, recent acute coronary syndrome within 30 days prior to study enrolment, that could mean exercise testing poses a risk to patient health, in the opinion of the investigator
7. Musculoskeletal comorbidity that will preclude the participant's ability to reliably complete the complete 6-minute walk test (6MWT)
8. Participation in another research project which may confound this study's research findings

• Myall KJ, West AG, Martinovic JL, Lam JL, Roque D, Wu Z, Maher TM, Molyneaux PL, Suh ES, Kent BD. Nocturnal Hypoxemia Associates With Symptom Progression and Mortality in Patients With Progressive Fibrotic Interstitial Lung Disease. Chest. 2023 Nov;164(5):1232-1242. doi: 10.1016/j.chest.2023.05.013. Epub 2023 May 13. PMID 37187434

• Alex West, MBBS, Principal investigator, Guys and St. Thomas NHS Foundation Hospital