Comparison of exercise training responses in COPD patients with and without Alpha-1 antitrypsin deficiency.

BACKGROUND: 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.

METHODS: 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" (AATDAUG+ ) or "off" (AATDAUG- ) augmentation therapy. 6MWD was assessed pre and post an inpatient 4-week PR program. Plasma level of creatinine was analysed at baseline.

RESULTS: 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 (AATDAUG+ : +51 ± 55 m, AATDAUG- : +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.

CONCLUSIONS: 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.