Dr Wells: The evidence base does not allow the value of BAL to be proven, and so use is dependent upon expert experience. By historical accident, BAL has not generally been performed in the United States but is widely used [elsewhere], and for this reason, experts inside and outside the United States tend to disagree on its value.
There is also some confusion on what is meant by routine diagnostic use. There are 2 subsets of patients with IPF: those who meet guideline diagnostic criteria for IPF without BAL information, and an equally large group of patients with IPF who do not meet formal guideline diagnostic criteria. In the latter group, the diagnosis must be made by putting in a good deal of additional information. The growing consensus is that BAL probably adds little in the first group but is often very valuable in the second group. Amalgamating the 2 groups makes no sense [Editor’s note: as the 2011 IPF guidelines seemed to do].
Dr Mooney: There is significant practice variation in the use of BAL for the diagnostic evaluation of interstitial lung diseases, including IPF. Although many European and some US centers have experience in the use of BAL for diagnostic evaluation, consensus guidelines for the diagnosis of IPF currently do not support its routine use.
Pulmonology Advisor: What are the points for and against using BAL in this way?
Dr Wells: Simply as a means of greatly reducing the likelihood of hypersensitivity pneumonitis, the most frequent differential diagnosis.
Dr Mooney: The potential utility of BAL in the diagnostic evaluation arises from its ability to identify a predominance of lymphocytes within the lung that may support an alternative diagnosis to IPF, specifically chronic hypersensitivity pneumonitis. Although some clinicians cite positive anecdotal experience with the use of BAL for this purpose, the literature supporting the ability of the presence or absence of BAL lymphocytosis to confidently alter the final diagnosis is limited.
Pulmonology Advisor: What should be next steps in this area in terms of research or otherwise?
Dr Wells: Formal prospective studies to prove the added value of BAL are needed. Clinician groups should record their diagnoses without considering BAL information and then review the diagnosis when BAL information is added. In this way, the frequency with which BAL helps can be quantified.
Dr Mooney: BAL use may ultimately have a role in the diagnostic evaluation of IPF, particularly in those with a possible radiographic pattern of IPF or where further definitive testing such as surgical lung biopsy is not obtainable, but further evidence supporting this is first needed. Prospective studies that blindly collect BAL samples as part of a multidisciplinary diagnostic evaluation are needed to help answer these questions.
Note: This interview was edited for length and clarity.
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