[Clinical trial endpoints in alpha-1-antitrypsin deficiency: interdisciplinary aspects]

Patients with alpha-1-antitrypsin deficiency (AAD) represent a small subgroup of subjects with chronic obstructive pulmonary disease (COPD). Only about 800 patients are registered in the German AAD registry, so that about 90 % of the estimated 8000 afflicted individuals have not yet been diagnosed. Clinical trials to demonstrate the efficacy of alpha-1-antitrypsin augmentation therapy are difficult not only due to the small number of potential participants. As in recent COPD trials, FEV (1) and other standard respiratory function parameters have failed to demonstrate statistically significant differences between treatment groups. The present article reviews and discusses both established and potentially new study endpoints. Novel parameters emerge within the field of diagnostic imaging. IT-supported analysis of lung density allows to quantify the extent of emphysema. The EXACTLE trial has shown that CT densitometry is able to document the progression of emphysema over 2 to 3 years. Magnetic resonance imaging (MRI) can serve as an adjunct to assess lung perfusion, ventilation, and breathing dynamics. In the future, prospective multi-centre studies will rather use imaging endpoints than classical respiratory function measurements such as FEV (1). In addition, diffusion capacity and combined endpoints such as the BODE index, which correlates with mortality in COPD, should be considered.