CLINICAL AND FUNCTIONAL ASSESSMENT OF PATIENTS WITH IDIOPATHIC PULMONARY FIBROSIS - RESULTS OF A 3 YEAR FOLLOW-UP

The purpose of this study was to analyse the information provided by different techniques used in the assessment of patients with idiopathic pulmonary fibrosis (IPF) and their role in the prediction of lung function decline with the disease. Twenty seven subjects with IPF (55+/-14 (mean+/-SD) yrs) were studied at the initial staging. Nineteen of them (70%) were included in a follow-up over 3 yrs (32+/-6 months), whilst the remaining 8 patients were lost to follow-up. During the period of the study, 6 of the 19 patients died. A significant correlation between diffusing capacity of the lungs for carbon monoxide (DLCO) (and carbon monoxide transfer coefficient (KCO)=DLCO/alveolar volume (VA)) and the increase in alveolar-arterial oxygen tension difference (A-aPO(2)) during exercise (Delta A-aPO(2)) was observed at diagnosis (r=-0.58). Despite the treatment with prednisone (1 mg.kg(-1) daily during 4 weeks, tapered to an individualized maintenance daily dose of 15-30 mg), the 13 patients controlled throughout the whole period of the study showed a marked impairment in lung volumes; forced vital capacity (FVC) -0.46+/-0.09 l, from 69+/-16 to 52+/-11% of predicted, and total lung capacity (TLC) -0.39+/-0.11 l, from 75+/-16 to 62+/-14 %, and in DLCO -0.6+/-0.2 mmol.min(-1).kPa(-1), from 56+/-15 to 47+/-18%, predicted. By contrast, both mean arterial oxygen tension (PaO2) and A-aPO(2) at rest remained unchanged throughout the 3 yrs follow-up. The Delta A-aPO(2) at the initial staging correlated with the increase in A-aPO(2) at rest measured both at 20 months and at the end of the for low-up (r=0.79 and r=0.76, respectively). Similarly, the initial KCO correlated with the increase in A-aPO(2) at rest measured at the end of the follow-up (r=-0.65). Although the number of patients evaluated is small, this study suggests that both the single-breath CO diffusing capacity and exercise testing (Delta A-aPO(2)) could be useful prognostic indicators of the decline of arterial oxygenation over time in IPF.