SURFACTANT PROTEIN-A PREDICTS SURVIVAL IN IDIOPATHIC PULMONARY FIBROSIS

The purpose of this study was to determine if the measurement of surfa ctant protein A (SP-A) in bronchoalveolar lavage (BAL) fluid predicts survival in patients with idiopathic pulmonary fibrosis (IPF). We perf ormed BAL on 44 patients with IPF and 33 healthy volunteers. SP-A and total phospholipid (PL) were measured in the surfactant pelleted by ce ntrifugation and expressed as a ratio to account for differences in th e alveolar surface area sampled. The mean SP-A/PL was lower in patient s with IPF than in healthy volunteers (31.8 +/- 2.8 versus 63.9 +/- 6. 4 mu g/mu mol, p = 0.006) and in patients who died within 2 yr than in those who survived (23.4 +/- 2.6 versus 37.5 +/- 4.2 mu g/mu mol, p = 0.015). Using Cox's proportional hazard model, we found that SP-A/PL modeled continuously was associated with survival time (p = 0.002). Th e 5-yr survival of patients with SP-A/PL above the median level for al l patients with IPF (29.7 mu g/mu mol) was more than twice that of pat ients below the median (68 versus 30%, p 0.007). SP-A/PL improved upon prediction of survival modeled by most routine physiologic variables with the exception of percent predicted TLC or the multifarious clinic al-radiographic-physiologic score (CRP). Cellular analysis of lavage d id not predict survival in this cohort of patients. We conclude that S P-A/PL is a biochemical marker in lavage that predicts survival in pat ients with IPF.