By providing evidence that complement alterations precede accelerated FEV1 decline, we extend previous associations between the levels of blood-derived complement proteins (C333,34, C435, C4b36, C5a37, C938, Factor B36) and COPD status (case vs. control), cross-sectional analyses of FEV1% predicted39,40, and emphysema severity41. This evidence concerns the gene VTN and chronic obstructive pulmonary disease.