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Washington Hospital Center Washington, DC Eisenhower Army Medical Center Augusta, GA
Correspondence to: Andrew F. Shorr, MD, MPH, FCCP, Pulmonary and Critical Care Medicine, Washington Hospital Center, Room 2D-38, 110 Irving St, NW, Washington, DC 20010; e-mail: afshorr{at}dnamail.com
To the Editor:
We read with interest the article by Berbescu et al1 regarding the role for transbronchial biopsy (TBB) in the diagnosis of usual interstitial pneumonia (UIP). The authors conclude that TBB may be more useful than previously appreciated in the diagnosis of UIP. We do not believe their data support this conclusion.
First, their analysis is purely retrospective and hence prone to multiple forms of bias. For example, as the authors themselves acknowledge, they were aware of the diagnosis prior to reviewing the TBB specimens. Without blinding of the pathologist as to the final diagnosis, one can draw no firm conclusions regarding the yield of TBB in patients suspected of having UIP. Second, selection bias is a major concern since subjects with UIP who underwent TBB are likely to be systematically different from those who did not undergo TBB. Third, the absence of a control arm of patients lacking UIP precludes any effort to calculate precisely the sensitivity and specificity of TBB. Similarly, they provide no denominator as to the number of subjects at either institution who underwent TBB for possible UIP during the study period.
Alternatively, two large, recent prospective analyses23 suggest that the value of TBB in suspected UIP is quite low. For example, Raghu and coworkers2 evaluated 59 consecutive patients thought to have UIP and found TBB to be nondiagnostic in 85% of subjects. A multicenter investigation3 reported an even lower yield for TBB (2 of 91 subjects). The low yield for TBB needs also to be balanced against the relative safety of surgical lung biopsy (SLB) in this population. One recent case series4 documents that most patients suspected of having UIP tolerate this procedure well.
Concern about pathologic interpretation also merits consideration. Nine of the 21 subjects with UIP in the report by Berbescu et al1 showed only features of nonspecific interstitial pneumonia on TBB. Hence, without proceeding to SLB, nearly 40% of the study population might have been substantially misclassified and perhaps faced a delayed referral for lung transplantation. Furthermore, in the hands of nonpulmonary pathologists there is the potential for substantial misdiagnosis. Even with large tissue specimens, nonpulmonary pathologists misdiagnosis UIP frequently.5 Increased reliance on TBB might further compound this issue. In short, although intriguing that in hindsight evidence of UIP can be detected on TBB, the data presented by Berbescu and colleagues1 should not prompt clinicians to routinely rely on TBB as a diagnostic test either to exclude or to confirm the diagnosis of UIP.
Footnotes
The authors have no conflicts of interest to disclose.
The author has no conflicts of interest to disclose.
References
David Geffen School of Medicine at UCLA Los Angeles, CA
Correspondence to: David A. Zisman, MD, Division of Pulmonary, Critical Care and Hospitalists, David Geffen School of Medicine at UCLA, 37–131 Center for the Health Sciences, Los Angeles, CA 90095; e-mail dzisman{at}mednet.ucla.edu
To the Editor:
I believe that Drs. Shorr, Lettieri, and Helman misinterpreted the message of our article (May 2006).1 This work generated a hypothesis that will require further testing. It was not intended to produce a clinical recommendation to use transbronchial lung biopsies (TBBs) to diagnose usual interstitial pneumonia (UIP). In our article, we clearly state that TBBs should be tested in a blinded fashion and in a cohort of diffuse lung diseases including UIP and non-UIP cases.1 However, it is undeniable, as we show in several of our figures, that features specific for UIP, such as patchwork pattern of interstitial fibrosis, fibroblastic foci, and honeycomb change,23 are readily recognizable in many TBB specimens.1 We did not report findings of nonspecific interstitial pneumonia in 9 of 21 patients, as Drs. Shorr, Lettieri, and Helman state. We make clear in the "Materials and Methods" section that findings were "nonspecific" if there was only interstitial fibrosis on TBB specimens.1 Unfortunately, it has become accepted, despite lack of convincing data, that TBBs are not useful in diagnosing idiopathic interstitial pneumonias. However, if in the future TBBs are found useful in diagnosing UIP from a pool of patients with diverse idiopathic interstitial pneumonias, many unnecessary surgical lung biopsies with associated morbidity and mortality could be prevented.4
References
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