S64 Changes in physiological phenotypes of  -1-antitrypsin deficiency with time

Abstract

Chronic Obstructive Pulmonary Disease (COPD), even due to a-1- antitrypsin deficiency (A1AD), is recognised as having distinct radiological, physiological and clinical phenotypes. Little is known about disease progression in physiologically defined phenotypes.1 We have identified a subgroup of patients with a reduced FEV1 but normal gas transfer determined by the lower limit of normal (LLN), that is, with standardised residual (SR) value = 3 years of complete annual follow-up data. These patients were followed for a mean of 5.9 (2.2 SD) years. Of these, 22 remained with isolated FEV1 abnormality (Group A) whereas 21 had developed evidence of a reduced K,co deficiency (Group B). Group A and B data at baseline and at last follow-up were compareddsee Abstract S64 Table 1.(Table presented). Result(s): There were no differences in FEV1, smoking, age or sex distribution between the groups. At baseline mean K,co SR was worse in Group B compared to Group A. However, Group A had significantly worse total Saint George's Respiratory questionnaire. score (SGRQ) at baseline. K,co SR significantly deteriorated in both groups during follow-up (p<0.001 in both cases) but this was not true for FEV1 SR. Group B had a significantly faster decline in K,co than Group A (p=0.005) resulting in all values falling below the LLN. Conclusion(s): About half of the A1AD patients with an isolated FEV1 abnormality at baseline have a decline in K,co faster than expected. Whether exacerbations, treatment or emphysema distribution relates to faster decline remains to be determined.