Present guidelines for the diagnosis of idiopathic pulmonary fibrosis require histological confirmation of surgical lung biopsy samples when high-resolution CT images are not definitive for usual interstitial pneumonia.
A study has assessed the predictive value of high-resolution CT in a cohort of patients with suspected idiopathic pulmonary fibrosis from a previous randomised trial.
ARTEMIS-IPF was a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial of Ambrisentan ( Volibris ) for adults aged 40-80 years with well-defined idiopathic pulmonary fibrosis and 5% or less honeycombing on high-resolution CT.
In December, 2010, an interim analysis showed lack of efficacy and the trial was stopped. In the present follow-on analysis, researchers have assessed patients who were screened for ARTEMIS-IPF who underwent high-resolution CT as part of screening and surgical lung biopsy as part of standard clinical care. A radiologist and a pathologist from a central panel independently assessed anonymised CT scans and biopsy samples.
Researchers calculated the positive and negative predictive value of high-resolution CT ( classified as usual interstitial pneumonia, possible usual interstitial pneumonia, and inconsistent with usual interstitial pneumonia ) for confirmation of histological patterns of usual interstitial pneumonia.
315 ( 29% ) of 1087 consecutively screened patients in ARTEMIS-IPF had both high-resolution CT and surgical lung biopsy samples.
108 of 111 patients who met high-resolution CT criteria for usual interstitial pneumonia had histologically confirmed usual interstitial pneumonia ( positive predictive value 97.3% ), as did 79 of 84 patients who met high-resolution CT criteria for possible usual interstitial pneumonia ( 94.0% ).
22 of 120 patients had an inconsistent high-resolution CT pattern for usual interstitial pneumonia that was histologically confirmed as not or possible usual interstitial pneumonia ( negative predictive value 18.3% ).
In the appropriate clinical setting, for patients with possible usual interstitial pneumonia pattern on high resolution CT, surgical lung biopsy sampling might not be necessary to reach a diagnosis of idiopathic pulmonary fibrosis if high-resolution CT scans are assessed by experts at regional sites familiar with patterns of usual interstitial pneumonia and management of idiopathic interstitial pneumonia. ( Xagena )
Raghu G et al, The Lancet Respiratory Medicine 2014; 2: 277-284