ILD Risk Factors

Kristin Highland, MD, discusses the common risk factors associated with ILD.

Ryan Haumschild, PharmD, MS, MBA: As we move on, I want to transition to Dr Highland. I want to focus on what are some of the risk factors associated with interstitial lung disease. What are some of the common causes of these different classifications that we talked about, and how are you screening patients for interstitial lung disease?

Kristin Highland, MD: Thank you for having me. As Dr [Daniel] Culver implied and Dr [Paul] Noble said, the fun part of treating interstitial lung disease is being the detective and trying to understand the cause. In idiopathic pulmonary fibrosis, idiopathic means no known cause, but we know that those patients tend to be a certain demographic. They tend to be older men, often with a history of smoking. We can say that smoking is a risk factor for interstitial lung disease. We have a very large group of patients with interstitial lung disease related to an underlying rheumatologic or autoimmune condition. Those patients are likely to have a pattern on pathology called NSIP [nonspecific interstitial pneumonia], and it can be a leading cause of morbidity and mortality.

Certainly, we look for diseases like scleroderma and rheumatoid arthritis or the idiopathic inflammatory myopathies. We can see interstitial lung disease with all our connective tissue diseases. We also see interstitial lung disease when patients are exposed to an organic antigen. We do a lot of questioning regarding what kind of pets patients have. Do they have a bird? Do they sleep on featherbedding? We ask about mold exposure, if they have a hot tub, and what their hobbies are. We do a very detailed occupational environmental history. We have occupational lung diseases that are pneumoconiosis, such as coal workers, and asbestosis, and borreliosis, and there’s an entire alphabet soup of interstitial lung diseases. Some of which are more fibrotic, and some of which are more inflammatory. Although many of these diseases share fibrosis as a common final pathway, we’re looking for patients who have significant evidence of inflammation that may also benefit from immunosuppressive therapies.

We don’t screen for interstitial lung disease, with the exception of patients with scleroderma, where there’s consensus that all patients with scleroderma immediately after the diagnosis of scleroderma should be screened for interstitial lung disease. Recommendations are that they should get an HRCT [high-resolution computed tomography] as well as pulmonary function testing. Screening recommendations don’t exist for our other connective tissue diseases, but we know in scleroderma, interstitial lung disease is 1 of the leading causes of morbidity and mortality.

Often in the setting of connective tissue disease, it’s difficult to have a heightened suspicion for interstitial lung disease. Patients may not be short of breath because their activities are curtailed by nonpulmonary reasons, such as arthritis or muscle weakness. Unfortunately for the patient with idiopathic pulmonary fibrosis or the patient with an environmental cause of their interstitial lung disease who come to us when the cat is already out of the bag, we don’t have good screening recommendations for those patients, although with certain occupational industries there are OSHA [Occupational Safety and Health Administration] recommendations for baseline pulmonary function testing.

Ryan Haumschild, PharmD, MS, MBA: You hit on a lot of really good things: catching this early and managing the patients are going to be key. There are a lot of environmental [concerns] but also comorbidities talking about rheumatology and some of these inflammatory disease states where we need to be on heightened alert. As a provider and as referrals into your clinic, how are some of these patients caught? Do you generally get referrals from primary care? Are there things that you’re utilizing within the electronic medical record to pick up on some of these risk factors? How does that stratification occur where you pick up on it before a patient has progressed in their disease?

Kristin Highland, MD: Often, the primary care provider hears crackles on examination and may refer a patient to us because of the abnormal pulmonary evaluation. Patients also may complain of dyspnea on exertion or a nonproductive cough, and we end up being referred patients for that reason. Pulmonary function tests often show restrictive physiology, a low-force vital capacity or total lung capacity, as well as a low diffusion capacity. That makes us think of interstitial lung disease as a possible cause for that restrictive ventilatory defect. Sometimes the rheumatologist picks up on a patient with interstitial lung disease and may refer the patient to us, particularly when they screen for patients with scleroderma.

Ryan Haumschild, PharmD, MS, MBA: I appreciate you talking through the details. It’s always helpful even from a population of health management [viewpoint] to make sure that the earlier we can treat this patient the better, and we can improve quality of life.

This transcript has been edited for clarity.

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