Assessing pulmonary disease and response to therapy: which test?

Because 75% of deaths attributable to sarcoidosis occur due to progressive respiratory failure, the staging of pulmonary disease and the accurate identification of changes in disease severity with time are both an essential part of clinical management. Historically, pulmonary function tests (PFTs) and chest radiographic appearances have been applied to both goals. Several additional investigations have been proposed as markers of active disease, including gallium scanning, positron emission tomographic (PET) scanning, high-resolution computed tomographic (HRCT) scanning, bronchoalveolar lavage, and candidate biomarkers such as serum angiotensin-converting enzyme (ACE) levels and serum interleukin (IL)-2 receptor levels. However, none of these tests has been shown to add value to PFTs and chest radiography, either in staging disease at baseline or in detecting change, although PET scanning merits further evaluation with particular reference to the suppression of activity with treatment in irreversible disease. Furthermore, no single pulmonary function or chest radiographic variable in isolation is accurate in all cases in this heterogeneous disease. Thus the evaluation of pulmonary disease in sarcoidosis is a multidisciplinary exercise, with the integration of PFTs (including measures of gas transfer) and chest radiographic findings (best assessed using simple user-friendly grading systems) with symptomatic severity and change.