Clinical practice guidelines separately describe radiologic patterns of usual interstitial pneumonia (UIP) and fibrotic hypersensitivity pneumonitis (fHP), without direction on whether or how to apply these approaches concurrently within a single patient.
How can we integrate guideline-defined radiologic patterns to diagnose interstitial lung disease (ILD) and what are the pitfalls associated with described patterns that require reassessment in future guidelines?
Patients from the Canadian Registry for Pulmonary Fibrosis underwent detailed reevaluation in standardized multidisciplinary discussion. CT scan features were quantified by chest radiologists masked to clinical data, and guideline-defined patterns were assigned. Clinical data then were provided to the radiologist and an ILD clinician, who jointly determined the leading diagnosis.
Clinical-radiologic diagnosis in 1,593 patients was idiopathic pulmonary fibrosis (IPF) in 26%, fHP in 12%, connective tissue disease-associated ILD (CTD-ILD) in 34%, idiopathic pneumonia with autoimmune features in 12%, and unclassifiable ILD in 10%. Typical and probable UIP patterns corresponded to a diagnosis of IPF in 66% and 57% of patients, respectively. Typical fHP pattern corresponded to an fHP clinical diagnosis in 65% of patients, whereas compatible fHP was nonspecific and associated with CTD-ILD or IPAF in 48% of patients. No pattern ruled out CTD-ILD. Gas trapping affecting > 5% of lung parenchyma on expiratory imaging was an important feature broadly separating compatible and typical fHP from other patterns (sensitivity, 0.77; specificity, 0.91).
An integrated approach to guideline-defined UIP and fHP patterns is feasible and supports > 5% gas trapping as an important branch point. Typical or probable UIP and typical fHP patterns have moderate predictive values for a corresponding diagnosis of IPF and fHP, although occasionally confounded by CTD-ILD; compatible fHP is nonspecific.

BACKGROUND: Since the latest 2017 French guidelines, knowledge about idiopathic pulmonary fibrosis has evolved considerably.
METHODS: Practical guidelines were drafted on the initiative of the Coordinating Reference Center for Rare Pulmonary Diseases, led by the French Language Pulmonology Society (SPLF), by a coordinating group, a writing group, and a review group, with the involvement of the entire OrphaLung network, pulmonologists practicing in various settings, radiologists, pathologists, a general practitioner, a health manager, and a patient association. The method followed the \"Clinical Practice Guidelines\" process of the French National Authority for Health (HAS), including an online vote using a Likert scale.
RESULTS: After a literature review, 54 guidelines were formulated, improved, and then validated by the working groups. These guidelines addressed multiple aspects of the disease: epidemiology, diagnostic procedures, quality criteria and interpretation of chest CT scans, lung biopsy indication and procedures, etiological workup, methods and indications for family screening and genetic testing, assessment of the functional impairment and prognosis, indication and use of antifibrotic agents, lung transplantation, management of symptoms, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.
CONCLUSIONS: These evidence-based guidelines are intended to guide the diagnosis and practical management of idiopathic pulmonary fibrosis.

Chest high-resolution computed tomography (HRCT) is the central diagnostic tool in discerning idiopathic pulmonary fibrosis (IPF) from other interstitial lung disease (ILDs). In 2018, new guidelines were published and the nomenclature for HRCT interpretation was changed. We sought to evaluate how clinicians\' interpretation would change based on reading HRCTs under the framework of the old versus new categorization.
We collated HRCTs from 50 random cases evaluated in the Inova Fairfax ILD clinic. Six ILD experts were provided the deidentified HRCTs. They were all instructed to independently provide two reads of each HRCT, based on the old and the new guidelines.
The kappa statistic for concordance for HRCT reads under old guidelines was 0.5, while for the new guidelines it was 0.38. Under the framework of the old guidelines, there were 22 HRCTs with unanimous consensus reads, while only 15 with the new guidelines. There were 12 HRCTs read unanimously as usual interstitial pneumonia (UIP) pattern based on both the old and the new guidelines. Ten HRCTs were read as a possible UIP pattern based on the old guidelines and were classified in nine cases as probable UIP and one indeterminate based on the new guidelines. Of the 28 inconsistent UIP HRCTs (old guidelines), 25 were read as alternative diagnosis suggested, two were read as indeterminate and one as probable UIP.
Implementation of the new guidelines to categorize HRCTs in ILD patients appears to be associated with greater inter-interpreter variability. How or whether new guidelines improve the care and management of ILD patients remains unclear.The reviews of this paper are available via the supplemental material section.

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic progressive fibrosing interstitial lung disease with a poor prognosis. High-resolution computed tomography (HRCT) plays an important role in the work-up of patients with suspected IPF. In HRCT IPF is characterized by the pattern of usual interstitial pneumonia (UIP). For a long time only supportive or immunosuppressive treatment was possible. The approval of antifibrotic agents in 2012 marked a turning point and triggered further clinical and scientific interest. Based on the recently gained knowledge the revised version of the international guidelines for the diagnosis of IPF was published in 2018, including instructions for HRCT interpretation. In this continued medical education article the relevant signs in HRCT are presented. The specifications given in the guidelines are elucidated.

BACKGROUND: This document presents the guidelines of the Polish Respiratory Society (PTChP, Polskie Towarzystwo Chorób Płuc) for diagnosis and treatment of idiopathic pulmonary fibrosis (IPF), developed by agroup of Polish experts.
METHODS: The recommendations were developed in the form of answers to previously formulated questions concer-ning everyday diagnostic and therapeutic challenges. They were developed based on acurrent literature review using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology.
RESULTS: We formulated 28 recommendations for diagnosis (8), pharmacological treatment (12) as well as non-pharma-cological and palliative therapy (8). The experts suggest that surgical lung biopsy (SLB) not be performed in patients with the probable usual interstitial pneumonia (UIP) pattern, with an appropriate clinical context and unanimous opinion of a multidisciplinary team. The experts recommend using antifibrotic agents in IPF patients and suggest their use irrespective of the degree of functional impairment. As regards non-pharmacological and palliative treatment, strong re-commendations were formulated regarding pulmonary rehabilitation, oxygen therapy (in patients with chronic respiratory failure), preventive vaccinations as well as referring IPF patients to transplant centres. Table 1 presents an aggregate list of recommendations.
CONCLUSIONS: The Polish Respiratory Society Working Group developed guidelines for IPF diagnosis and treatment.