Current concepts in and modes for measurement of activity in interstitial lung disease

Activity in interstitial lung disease is indicated by the progression of illness, but is neither an estimate of total disease nor can it be equated with the outcome or need for therapy. There is no unifying concept of activity or progression of disease that will fit the decision processes for all of interstitial lung disease. Great effort has been directed to identifying clinical indices, serum markers, bronchoalveolar lavage findings, and imaging techniques that predict activity or progression from single observations at the time of diagnosis, and thus allowing early recognition of patients who have differing natural history of disease. The past year has seen special emphasis on patient symptoms, initial results of pulmonary function tests, and especially high-resolution computed tomography imaging at the time of diagnosis and the relation these factors have to disease progression, response to therapy, and survival.