High-Resolution CT Can Identify IPF Without Lung Biopsy

Diedtra Henderson

February 19, 2014

For certain elderly patients, an expert team skilled at reading high-resolution computed tomography (CT) scans can confidently diagnose idiopathic pulmonary fibrosis (IPF) in the absence of honeycombing, averting the need for patients to undergo risky surgical lung biopsies, according to a retrospective study conducted by Ganesh Raghu, MD, from the Center for Interstitial Lung Diseases, University of Washington Medical Center, Seattle, and colleagues. The work was published online February 18 in the Lancet Respiratory Medicine.

Patients with IPF have worsening respiratory symptoms and deteriorating pulmonary function, and they typically die from respiratory failure within 5 years of diagnosis. Accurate diagnosis is key to guiding treatment, enrolling patients in clinical trials, and prioritizing lung transplants, according to the authors."Diagnosis is made with the highest degree of confidence when clinical, radiological, and pathological data are reviewed by a multidisciplinary discussion team, consisting of a clinician, a radiologist, and a pathologist who all have expertise in the diagnosis of interstitial lung diseases," the authors write.

All 18 authors have financial relationships with the study sponsor.

The research team included patients aged 40 to 80 years who have well-defined IPF who had been screened for a randomized, double-blind, placebo-controlled, multicenter phase 3 trial that was scrapped when the medicine being studied, ambrisentan (Letairis, Gilead Sciences, Inc), failed to show efficacy. Some 315 (29%) of 1087 consecutively screened patients in the trial had both high-resolution CT and surgical lung biopsy samples. Patients had to show less than 5% honeycombing on the high-resolution CT to qualify for inclusion. The positive predictive value of the CT scans ranged from 94.0% to 97.3%.

Dr. Raghu and coauthors note that the success of this diagnostic technique hinges on 2 key conditions.

"The first condition is that the clinical presentation and demographics are typical of [IPF] and were ascertained by an expert in interstitial lung disease. Patients should have a thorough history taken for possible exposure to overt and occult factors in the patient's environment and lack clinical and serological features of collagen vascular diseases," the authors write. "The second condition is that high-resolution CT images, assessed by a radiologist with expertise in interstitial lung disease, show a subpleural basal predominant reticular abnormality with the absence of atypical features for usual interstitial pneumonia pattern."

An accompanying commentary notes that current guidelines neglect a subset of patients: those whose CT scans lack honeycombing and who do not wish to undergo high-risk, invasive lung biopsies.

"Although further prospective studies could provide confirmation, patients who have suspected [IPF] without honeycombing on high-resolution CT could in future be spared the risks of lung biopsy sampling and be given a confident diagnosis of [IPF] on the basis of clinical and radiological findings alone," writes Simon P. Hart, MBChB, PhD, from Hull York Medical School, Centre for Cardiovascular and Metabolic Research, Cottingham, United Kingdom.

"Absence of definitive honeycombing on high-resolution CT should prompt increased scrutiny for detection of atypical clinical presentation (including consideration of underlying environmental and collagen vascular disease) and radiological findings," the study authors conclude. "However, our study suggests that high-resolution CT is appropriate for diagnosis of [IPF] in patients with a possible pattern of usual interstitial pneumonia in the appropriate clinical setting."

Financial support for the study was provided by Gilead Sciences. Twelve of 18 study authors disclosed serving as paid consultants for Gilead. Four authors disclosed being Gilead employees and owning company stock. One author disclosed being an employee of one of Gilead's contracted vendors. Another author disclosed owning Gilead stock. Dr. Hull has disclosed no relevant financial relationships.

Lancet Respir Med. Published online February 18, 2014. Article abstract, Editorial extract

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