Sami M. Alyami, B.Pharm, MBBS, and Onofre Moran-Mendoza, MD, MSc, PhD, on Whether FEV1 Can Predict Pulmonary Fibrosis Sooner Than Restrictive Ventilation
Idiopathic pulmonary fibrosis (IPF) is the scarring of the lungs that has unknown origins. IPF affects an estimated 200,000 people in the United States and 5 million people worldwide, with a 50% mortality rate in the 3 to 5 years after diagnosis, according to the American Thoracic Society (ATS).
A recent study assessed increased expiratory flows as the earliest pulmonary function test abnormality in patients with IPF and other interstitial lung diseases (ILDs).1 This research could lead to a quicker diagnosis and treatment of patients with IPF.
Consultant360 spoke with the presenters and coauthors of this study: Sami M. Alyami, B.Pharm, MBBS, who is an Interstitial Lung Disease Fellow at Queen's University in Kingston, Ontario, Canada; and Onofre Moran-Mendoza, MD, MSc, PhD, who is an associate professor of medicine in the Division of Respiratory and Sleep Medicine at Queen's University.
Consultant360: Can you tell us a little bit more about your study and what you found?
Drs Alyami and Mendoza: The term “interstitial lung disease” (or ILD) encompasses a diverse group of diseases that involve inflammation and fibrosis of the alveolo-capillary space (interstitium) in the lungs. IPF is most common ILD of unknown cause. The majority of ILDs, including IPF, typically cause a restrictive ventilatory defect in pulmonary function tests (PFTs). However, about 25% of patients with ILD do not have evidence of restriction on PFTs. Low carbon monoxide diffusing capacity (DLCO) is traditionally considered to be the earliest abnormality on PFTs in patients with ILD.
For our study, we analyzed the PFT results of incident cases of ILD in Kingston, Ontario, Canada, between 2013 and 2017, to assess whether increased expiratory flows—that can be easily measured with simple spirometry—can precede any other functional abnormality on PFTs.
We found that abnormally high FEV1/FVC is the earliest abnormality observed on PFTs in patients with ILD and IPF.
C360: What do your results mean for practicing pulmonary specialists?
Drs: High FEV1/FVC could allow you to identify patients with ILD or IPF even before there is evidence of a restrictive pattern on PFTs or when the diffusing capacity is decreased. This can be detected with simple spirometry, leading to earlier diagnosis and treatment.
C360: DLCO is a traditional method for diagnosing IPF, though it is expensive and complex. What is a cheaper and/or easier alternative for diagnosing IPF?
Drs: Our study shows that simple spirometry, which measures expiratory flows including FEV1/FVC, is the cheapest and more readily available pulmonary function test for pulmonologists and even primary care physicians.
C360: Can you tell us a little bit more about IPF? What is it, and how is it treated?
Drs: IPF is one of the most common ILDs and is the most common idiopathic interstitial pneumonia (IIP). It is a chronic fibrotic disease characterized by lung scarring and progressive loss of function. It is associated with a radiological and/or histopathologic pattern of usual interstitial pneumonia. It is associated with a high mortality rate, with a median survival of 3 to 5 years if untreated; fortunately, there are currently 2 antifibrotic drugs available worldwide that slow disease progression: pirfenidone and nintedanib.
C360: What else should pulmonary specialists know about IPF?
Drs: IPF is of particular clinical interest because it is often misdiagnosed and managed inappropriately with several medications for other pulmonary and cardiac conditions before the proper diagnosis is established. Frequently, the diagnosis of IPF is delayed up to 1 year after symptoms start, with the resulting progression of the disease, functional loss, decreased quality of life, and increased risk of death. Hence, it is important to think about IPF earlier, since we currently have effective drugs that could slow the progression of the disease and reduce mortality.
There are very few specific abnormalities that allow clinicians suspecting the disease, such as the presence of fine (“Velcro”) crackles on chest auscultation and findings of characteristic abnormalities on high-resolution chest computed tomography. Based on the results of our study, clinicians should also consider IPF when the FEV1/FVC or other expiratory flows are increased. This finding could result in early diagnosis and treatment of IPF.
References:
- Assessment of increased expiratory flows as the earliest pulmonary function test abnormalities in patients with idiopathic pulmonary fibrosis and interstitial lung diseases. Paper presented at: American Thoracic 2018; May 18-23, 2018; San Diego, CA. http://www.abstractsonline.com/pp8/#!/4499/presentation/22086. Accessed May 22, 2018.