Summary of 2018 Idiopathic Pulmonary Fibrosis Diagnostic Guidelines

A new clinical practice guidelines summary for clinicians regarding idiopathic pulmonary fibrosis (IPF) has been released that describes clinical manifestations and diagnostic interventions for the disease. The report was published in the American Journal of Respiratory and Critical Care Medicine.

According to the guidelines, a useful strategy for evaluating the severity of lung function impairment in monitoring IPF progression is pulmonary function testing. As IPF progresses, single breath diffusing capacity of the lungs for carbon monoxide tends to decrease. The preferred diagnostic strategy for IPF includes volumetric scanning of the chest by high-resolution computed tomography (HRCT). The new guideline contains information on 4 diagnostic categories: Usual Interstitial Pneumonia (UIP) pattern, probable UIP pattern, indeterminate for UIP pattern, and alternative diagnosis. In addition, the new guideline describes 4 distinct histopathologic patterns for IPF on biopsies.

In order for IPF to be diagnosed, other causes of interstitial lung disease (ILD), including domestic and occupational environmental exposures, connective tissue disease (CTD), drug toxicity, should be excluded. In some instances, a pattern on HRCT without a biopsy that is “probable UIP” may result in an IPF diagnosis. According to the guideline summary, initial examination should identify the underlying contributor of interstitial lung disease (ILD). “If a specific diagnosis is not made,” the investigators wrote, “then a multidisciplinary discussion (MDD) focused on clinical findings, HRCT features, and, as appropriate, lung biopsy, may help ascertain or exclude the diagnosis of IPF.”

For identifying the most appropriate diagnostic intervention, the researchers recommended taking into account 8 different aspects of patient management: medical history, serologic testing for CTDs, cellular analysis of bronchoalveolar lavage fluid, surgical lung biopsy, transbronchial lung biopsy, transbronchial lung cryobiopsy, multidisciplinary discussion, and evaluation of serum biomarkers.

“The roles of genetic testing and blood-based biomarkers in routine IPF diagnosis remain uncertain but may soon make their way into practice,” the researchers wrote in their discussion of future directions. “Additional research is also needed to define the roles of [bronchoalveolar lavage], quantitative and texture-based CT [computed tomography] methods, and clinical prediction models in IPF diagnosis.”

Reference

Thomson CC, Duggal A, Bice T, Lederer DJ, Wilson KC, Raghu G. 2018 clinical practice guideline summary for practicing clinicians: diagnosis of idiopathic pulmonary fibrosis [published online December 13, 2018]. Ann Am Thorac Soc. doi:10.1513/AnnalsATS.201809-604CME