“There is definitely a delay from the time of symptom onset to the time that they are even evaluated for ILD,” said Dr. Kulkarni of the department of pulmonary, allergy and critical care medicine at the University of Alabama, Birmingham. “Some patients have had a significant loss of lung function by the time they come to see us. By that point we are limited by what treatment options we can offer.”
Dr. Tejaswini Kulkarni
Interstitial lung disease is an umbrella term for a group of disorders involving progressive scarring of the lungs – typically irreversible – usually caused by long-term exposure to hazardous materials or by autoimmune effects. It includes idiopathic pulmonary fibrosis (IPF), a disease that is fairly rare but which has therapy options that can be effective if caught early enough. The term pulmonary fibrosis refers to lung scarring. Another type of ILD is pulmonary sarcoidosis, in which small clumps of immune cells form in the lungs in an immune response sometimes following an environmental trigger, and can lead to lung scarring if it doesn’t resolve.
Cases of ILD appear to be on the rise, and COVID-19 has made diagnosing it more complicated. One study found the prevalence of ILD and pulmonary sarcoidosis in high-income countries was about 122 of every 100,000 people in 1990 and rose to about 198 of every 100,000 people in 2017. The data were pulled from the Global Burden of Diseases, Injuries, and Risk Factors Study 2017. Globally, the researchers found a prevalence of 62 per 100,000 in 1990, compared with 82 per 100,000 in 2017.
If all of a patient’s symptoms have appeared post COVID and a physician is seeing a patient within 4-6 weeks of COVID symptoms, it is likely that the symptoms are COVID related. But a full work-up is recommended if a patient has lung crackles, which are an indicator of lung scarring, she said.
“The patterns that are seen on CT scan for COVID pneumonia are very distinct from what we expect to see with idiopathic pulmonary fibrosis,” Dr. Kulkarni said. “Putting all this information together is what is important to differentiate it from COVID pneumonia, as well as other types of ILD.”
A study published earlier this year found similarities between COVID-19 and IPF in gene expression, their IL-15-heavy cytokine storms, and the type of damage to alveolar cells. Both might be driven by endoplasmic reticulum stress, they found.
“COVID-19 resembles IPF at a fundamental level,” they wrote.
Jeffrey Horowitz, MD, a pulmonologist and professor of medicine at the Ohio State University, said the need for early diagnosis is in part a function of the therapies available for ILD.
“They don’t make the lung function better,” he said. “So delays in diagnosis mean that there’s the possibility of underlying progression for months, or sometimes years, before the diagnosis is recognized.”
In an area in which diagnosis is delayed and the prognosis is dire – 3-5 years in untreated patients after diagnosis – “there’s a tremendous amount of nihilism out there” among patients, he said.
He said patients with long-term shortness of breath and unexplained cough are often told they have asthma and are prescribed inhalers, but then further assessment isn’t performed when those don’t work.