This is a prospective, real world, multicenter, registry of patients with pulmonary hypertension associated with interstitial lung disease (PH-ILD) and interstitial lung disease (ILD).

The purpose of this study is to capture and analyze patient characteristics, treatment patterns, and clinical outcomes of patients with PH-ILD, with the goal of enhancing our current understanding of the disease state and its treatment outcomes. The study also aims to describe the disease trajectory of ILD patients at risk of pulmonary hypertension (PH).

In this registry, patients will be enrolled into 1 of 4 cohorts. Cohort 1 will include approximately 200 patients who are not receiving inhaled treprostinil at time of study enrollment. Cohort 2 will include approximately 300 patients who are newly initiated on Tyvaso/Tyvaso DPI. Cohort 3 will include approximately 300 patients who have been receiving Tyvaso/Tyvaso DPI for >90 days. Cohort 4 will include approximately 100 ILD patients with a prior right heart catheterization (RHC) not meeting the definition of PH.

As part of the registry, assessments will be completed for data collection in 6- or 12 month intervals, unless the data are already available via standard of care. This patient registry will follow patients for up to 5 years after enrollment.

Assessments include pulmonary function tests (PFTs) including diffusing capacity of the lungs for carbon monoxide (DLCO); high resolution computed tomography (HRCT); vital signs; 6-Minute Walk Test; blood draw for plasma N-terminal pro-BNP (NT-proBNP) concentration, genetics analysis, biomarker analysis; echocardiography; EuroQoL 5 Dimension 5 Level Questionnaire (EQ-5D-5L); King's Brief Interstitial Lung Disease Questionnaire (K-BILD); Living with Pulmonary Fibrosis Questionnaire (L-PF); Therapy Administration Questionnaire; emPHasis-10 Questionnaire; healthcare resource utilization; current medications and rehabilitation; WHO functional class; transplant status; palliative care data; survival data; and RHC.

Inclusion Criteria:

1. Adults aged 18 years or older

2. Diagnosis of fibrotic ILD based on high-resolution computed tomography imaging, including but not limited to:

   1. Idiopathic interstitial pneumonia, including idiopathic pulmonary fibrosis
   2. Autoimmune ILD
   3. Chronic hypersensitivity pneumonitis
   4. Nonspecific interstitial pneumonia
   5. Occupational lung disease
   6. Combined pulmonary fibrosis and emphysema with fibrosis greater than the extent of emphysema on lung imaging as determined by the Investigator

3. For patients to be eligible for Cohorts 1 to 3: RHC confirmed PH (mean pulmonary artery pressure >20 mmHg, pulmonary artery wedge pressure

   ≤15 mmHg, pulmonary vascular resistance >2 WU).

4. For patients to be eligible for Cohort 1, they must not be receiving inhaled treprostinil at Baseline.

5. For patients to be eligible for Cohort 2, they must have initiated

Tyvaso/Tyvaso DPI at 1 of the following time points:

1. Baseline
2. ≤90 days prior to Baseline 6. For patients to be eligible for Cohort 3, they must be receiving Tyvaso/Tyvaso DPI at Baseline and for >90 days prior to Baseline. 7. For patients to be eligible for Cohort 4: Prior RHC not meeting the definition of PH as described in Inclusion Criterion 3 but has a pulmonary artery wedge pressure ≤15 mmHg. 8. Co-enrollment in other observational or interventional studies is permitted. 9. Patient is willing and able to provide informed consent and complete surveys/questionnaires in English or Spanish.

Exclusion Criteria:

1. Confirmed diagnosis of Group 1, 2, 4, or 5 PH

   a. In cases in which a patient has a diagnosis of PH-ILD along with a concomitant diagnosis of another PH group (eg, Group 1), enrollment may be permitted at the Investigator's discretion if, in their clinical judgment, PH-ILD is the predominant driver of the patient's PH.

2. Confirmed diagnosis of Group 3 PH associated with lung diseases and or hypoxia other than fibrotic ILD, as outlined in Inclusion Criterion 2.

3. Patients receiving inhaled treprostinil (Yutrepia™) at Baseline. Patients receiving other forms of PH therapy will be eligible for enrollment.

Patients with a diagnosis of pulmonary hypertension associated with interstitial lung disease or interstitial lung disease. This includes patients who are and aren't receiving inhaled treprostinil, excluding patients receiving Yutrepia™ at Baseline.