Potential Limitations of Clinical Criteria for the Diagnosis of Idiopathic Pulmonary Fibrosis/Cryptogenic Fibrosing Alveolitis

Abstract

Background: The need to perform surgical lung biopsy (SLB) in all cases of suspected idiopathic pulmonary fibrosis/cryptogenic fibrosing alveolitis (IPF/CFA) is controversial. The American Thoracic Society (ATS) and the European Respiratory Society (ERS) recently endorsed explicit clinical criteria for the diagnosis of IPF/CFA in the absence of SLB. Prior studies evaluating clinical criteria for the diagnosis of IPF/CFA have been limited in that either they were performed by clinicians with expertise in the diagnosis of IPF/CFA or they did not utilize explicit diagnostic criteria. We investigated the accuracy of the ATS/ERS criteria when applied in a general pulmonary medicine setting. Objectives: To determine the interobserver variability of clinical criteria for the diagnosis of IPF/CFA. Methods: This was a retrospective, blinded evaluation by three board certified pulmonary physicians without extensive experience in the evaluation of IPF/CFA performed at a United States Army tertiary care academic medical center. Patients referred for surgical lung biopsy as part of a diagnostic evaluation of interstitial lung disease (ILD) were evaluated. The physicians reviewed high-resolution computed tomography scans of the chest (HRCT) and clinical data for each patient. The physicians were blinded to all other data and to the opinions of other study participants. Employing the histologic presence of usual interstitial pneumonia (UIP) coupled with appropriate clinical findings as the gold standard for a diagnosis of IPF/CFA we determined the accuracy and interobserver variability for a diagnosis of IPF/CFA based on HRCT alone and based on the ATS/ERS clinical criteria. Results: The sensitivity and positive predictive value for a HRCT diagnosis of IPF/CFA were 71% each while specificity and negative predictive value were 67% each. For the ATS/ERS criteria sensitivity, specificity, positive predictive value and negative predictive value were 71, 75, 77 and 69%, respectively. The interobserver variability, expressed as a kappa coefficient, for HRCT and the ATS/ERS criteria were 0.59 and 0.53, respectively. Conclusions: Both HRCT and the ATS/ERS clinical criteria may lead to misdiagnosis of patients with ILD. Further studies are needed to fully characterize the accuracy of these tests when applied in a routine pulmonary medicine practice setting.

Functional Predictors of Exertional Dyspnea, 6-min Walking Distance and HRCT Fibrosis Score in Idiopathic Pulmonary Fibrosis

“…Interestingly, a recent survey in the United States revealed that most pulmonologists would accept an HRCT diagnosis of IPF/usual interstitial pneumonitis without lung biopsy [41]. Secondly, although the diagnostic accuracy of HRCT scan in identifying IPF is considered high [42], considerable overlap in CT patterns between different IIPs, such as IPF and nonspecific interstitial pneumonia (NSIP), has been observed [43]. Prevalent ground glass attenuation is regarded as a typical finding of NSIP [44].…”

Radiological versus Histopathological Diagnosis of Usual Interstitial Pneumonia in the Clinical Practice: Does It Have Any Survival Difference?

“…Additionally, some authors stress that CT findings are not specific enough to define prognosis, also pointing out the considerable interobserver variability that is seen in the clinical and radiologic diagnoses, even when performed by experts in the field [11,12]. This study examines whether UIP-associated mortality is different in patients diagnosed by HRCT features considered definite of UIP and in patients with no definite radiological diagnosis that required histological confirmation of diagnoses.…”

Idiopathic Pulmonary Fibrosis: Evaluation with Positron Emission Tomography

“…The high-resolution CT scan has better characterized the changes in interstitial lung disease and improved the confidence in diagnosis, but not necessarily disease activity [9, 10]. There remains considerable error using combined clinical diagnostic criteria or even high-resolution CT scans with the accuracy of these methods hovering in the 70% range [11, 12]. Some have advocated the use of serial high-resolution CT scans in monitoring these patients, being able to better document increasing honeycomb changes or fibrosis in those with progressive disease [13].…”