The benefits of pulmonary rehabilitation (PR) on fatigue-resistant skeletal muscle fibre type I have been found to be smaller in COPD patients with alpha-1 antitrypsin deficiency (AATD) than in those without AATD. Alpha-1 antitrypsin (AAT) augmentation therapy was suggested as a potential factor of influence. Whether this finding mirrors different improvements in 6-min walk distance (6MWD) between both groups remains unknown.

140 patients with AATD-related COPD (phenotype PiZZ, FEV₁: 31 ± 8%pred.) and 280 COPD patients without AATD (FEV₁: 31 ± 8%pred.) were matched for baseline 6MWD and included in a retrospective analysis. AATD patients were divided into those “on” (AATD_AUG+) or “off” (AATD_AUG-) augmentation therapy. 6MWD was assessed pre and post an inpatient 4-week PR program. Plasma level of creatinine was analysed at baseline.

In AATD and COPD patients with comparable initial 6MWD (331 ± 106 m and 326 ± 101 m, p = n.s.), improvements in 6MWD following PR were similar (+49 ± 49 m and +53 ± 52 m, intra-group change: p < 0.001). Notably, 68% of AATD and 65% of COPD responded well with a clinically relevant 6MWD improvement of ≥30 m. The improvement in 6MWD was independent of gender, age, pack years, SF36 mental score and body mass index. The augmentation therapy with AAT did not influence 6MWD outcome (AATD_AUG+: +51 ± 55 m, AATD_AUG-: +47 ± 40 m, p = n.s.). Only in AATD group, higher baseline creatinine levels and lower 6MWD were positive predictors for the PR-related increase in 6MWD.

Independently of the genetic variant of AAT, COPD patients achieved the same training-related benefit in 6MWD. Augmentation therapy showed no effect on 6MWD adaptation during PR.